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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/memory.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
6
7/*
8 * demand-loading started 01.12.91 - seems it is high on the list of
9 * things wanted, and it should be easy to implement. - Linus
10 */
11
12/*
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
15 *
16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17 * would have taken more than the 6M I have free, but it worked well as
18 * far as I could see.
19 *
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21 */
22
23/*
24 * Real VM (paging to/from disk) started 18.12.91. Much more work and
25 * thought has to go into this. Oh, well..
26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
27 * Found it. Everything seems to work now.
28 * 20.12.91 - Ok, making the swap-device changeable like the root.
29 */
30
31/*
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh (alex@cconcepts.co.uk)
34 *
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * (Gerhard.Wichert@pdb.siemens.de)
37 *
38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39 */
40
41#include <linux/kernel_stat.h>
42#include <linux/mm.h>
43#include <linux/hugetlb.h>
44#include <linux/mman.h>
45#include <linux/swap.h>
46#include <linux/highmem.h>
47#include <linux/pagemap.h>
Hugh Dickins9a840892009-09-21 17:02:01 -070048#include <linux/ksm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070049#include <linux/rmap.h>
50#include <linux/module.h>
Shailabh Nagar0ff92242006-07-14 00:24:37 -070051#include <linux/delayacct.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070052#include <linux/init.h>
Peter Zijlstraedc79b22006-09-25 23:30:58 -070053#include <linux/writeback.h>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080054#include <linux/memcontrol.h>
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070055#include <linux/mmu_notifier.h>
Hugh Dickins3dc14742009-01-06 14:40:08 -080056#include <linux/kallsyms.h>
57#include <linux/swapops.h>
58#include <linux/elf.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090059#include <linux/gfp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
Alexey Dobriyan6952b612009-09-18 23:55:55 +040061#include <asm/io.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070062#include <asm/pgalloc.h>
63#include <asm/uaccess.h>
64#include <asm/tlb.h>
65#include <asm/tlbflush.h>
66#include <asm/pgtable.h>
67
Jan Beulich42b77722008-07-23 21:27:10 -070068#include "internal.h"
69
Andy Whitcroftd41dee32005-06-23 00:07:54 -070070#ifndef CONFIG_NEED_MULTIPLE_NODES
Linus Torvalds1da177e2005-04-16 15:20:36 -070071/* use the per-pgdat data instead for discontigmem - mbligh */
72unsigned long max_mapnr;
73struct page *mem_map;
74
75EXPORT_SYMBOL(max_mapnr);
76EXPORT_SYMBOL(mem_map);
77#endif
78
79unsigned long num_physpages;
80/*
81 * A number of key systems in x86 including ioremap() rely on the assumption
82 * that high_memory defines the upper bound on direct map memory, then end
83 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
84 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
85 * and ZONE_HIGHMEM.
86 */
87void * high_memory;
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
89EXPORT_SYMBOL(num_physpages);
90EXPORT_SYMBOL(high_memory);
Linus Torvalds1da177e2005-04-16 15:20:36 -070091
Ingo Molnar32a93232008-02-06 22:39:44 +010092/*
93 * Randomize the address space (stacks, mmaps, brk, etc.).
94 *
95 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
96 * as ancient (libc5 based) binaries can segfault. )
97 */
98int randomize_va_space __read_mostly =
99#ifdef CONFIG_COMPAT_BRK
100 1;
101#else
102 2;
103#endif
Andi Kleena62eaf12006-02-16 23:41:58 +0100104
105static int __init disable_randmaps(char *s)
106{
107 randomize_va_space = 0;
OGAWA Hirofumi9b410462006-03-31 02:30:33 -0800108 return 1;
Andi Kleena62eaf12006-02-16 23:41:58 +0100109}
110__setup("norandmaps", disable_randmaps);
111
Hugh Dickins62eede62009-09-21 17:03:34 -0700112unsigned long zero_pfn __read_mostly;
Hugh Dickins03f64622009-09-21 17:03:35 -0700113unsigned long highest_memmap_pfn __read_mostly;
Hugh Dickinsa13ea5b2009-09-21 17:03:30 -0700114
115/*
116 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
117 */
118static int __init init_zero_pfn(void)
119{
120 zero_pfn = page_to_pfn(ZERO_PAGE(0));
121 return 0;
122}
123core_initcall(init_zero_pfn);
Andi Kleena62eaf12006-02-16 23:41:58 +0100124
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800125
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -0800126#if defined(SPLIT_RSS_COUNTING)
127
KAMEZAWA Hiroyukia3a2e762010-04-06 14:34:42 -0700128static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -0800129{
130 int i;
131
132 for (i = 0; i < NR_MM_COUNTERS; i++) {
133 if (task->rss_stat.count[i]) {
134 add_mm_counter(mm, i, task->rss_stat.count[i]);
135 task->rss_stat.count[i] = 0;
136 }
137 }
138 task->rss_stat.events = 0;
139}
140
141static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
142{
143 struct task_struct *task = current;
144
145 if (likely(task->mm == mm))
146 task->rss_stat.count[member] += val;
147 else
148 add_mm_counter(mm, member, val);
149}
150#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
151#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
152
153/* sync counter once per 64 page faults */
154#define TASK_RSS_EVENTS_THRESH (64)
155static void check_sync_rss_stat(struct task_struct *task)
156{
157 if (unlikely(task != current))
158 return;
159 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
160 __sync_task_rss_stat(task, task->mm);
161}
162
163unsigned long get_mm_counter(struct mm_struct *mm, int member)
164{
165 long val = 0;
166
167 /*
168 * Don't use task->mm here...for avoiding to use task_get_mm()..
169 * The caller must guarantee task->mm is not invalid.
170 */
171 val = atomic_long_read(&mm->rss_stat.count[member]);
172 /*
173 * counter is updated in asynchronous manner and may go to minus.
174 * But it's never be expected number for users.
175 */
176 if (val < 0)
177 return 0;
178 return (unsigned long)val;
179}
180
181void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
182{
183 __sync_task_rss_stat(task, mm);
184}
185#else
186
187#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
188#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
189
190static void check_sync_rss_stat(struct task_struct *task)
191{
192}
193
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -0800194#endif
195
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196/*
197 * If a p?d_bad entry is found while walking page tables, report
198 * the error, before resetting entry to p?d_none. Usually (but
199 * very seldom) called out from the p?d_none_or_clear_bad macros.
200 */
201
202void pgd_clear_bad(pgd_t *pgd)
203{
204 pgd_ERROR(*pgd);
205 pgd_clear(pgd);
206}
207
208void pud_clear_bad(pud_t *pud)
209{
210 pud_ERROR(*pud);
211 pud_clear(pud);
212}
213
214void pmd_clear_bad(pmd_t *pmd)
215{
216 pmd_ERROR(*pmd);
217 pmd_clear(pmd);
218}
219
220/*
221 * Note: this doesn't free the actual pages themselves. That
222 * has been handled earlier when unmapping all the memory regions.
223 */
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000224static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
225 unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226{
Martin Schwidefsky2f569af2008-02-08 04:22:04 -0800227 pgtable_t token = pmd_pgtable(*pmd);
Hugh Dickinse0da3822005-04-19 13:29:15 -0700228 pmd_clear(pmd);
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000229 pte_free_tlb(tlb, token, addr);
Hugh Dickinse0da3822005-04-19 13:29:15 -0700230 tlb->mm->nr_ptes--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231}
232
Hugh Dickinse0da3822005-04-19 13:29:15 -0700233static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
234 unsigned long addr, unsigned long end,
235 unsigned long floor, unsigned long ceiling)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236{
237 pmd_t *pmd;
238 unsigned long next;
Hugh Dickinse0da3822005-04-19 13:29:15 -0700239 unsigned long start;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240
Hugh Dickinse0da3822005-04-19 13:29:15 -0700241 start = addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 pmd = pmd_offset(pud, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 do {
244 next = pmd_addr_end(addr, end);
245 if (pmd_none_or_clear_bad(pmd))
246 continue;
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000247 free_pte_range(tlb, pmd, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 } while (pmd++, addr = next, addr != end);
249
Hugh Dickinse0da3822005-04-19 13:29:15 -0700250 start &= PUD_MASK;
251 if (start < floor)
252 return;
253 if (ceiling) {
254 ceiling &= PUD_MASK;
255 if (!ceiling)
256 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 }
Hugh Dickinse0da3822005-04-19 13:29:15 -0700258 if (end - 1 > ceiling - 1)
259 return;
260
261 pmd = pmd_offset(pud, start);
262 pud_clear(pud);
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000263 pmd_free_tlb(tlb, pmd, start);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264}
265
Hugh Dickinse0da3822005-04-19 13:29:15 -0700266static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
267 unsigned long addr, unsigned long end,
268 unsigned long floor, unsigned long ceiling)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269{
270 pud_t *pud;
271 unsigned long next;
Hugh Dickinse0da3822005-04-19 13:29:15 -0700272 unsigned long start;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273
Hugh Dickinse0da3822005-04-19 13:29:15 -0700274 start = addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 pud = pud_offset(pgd, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 do {
277 next = pud_addr_end(addr, end);
278 if (pud_none_or_clear_bad(pud))
279 continue;
Hugh Dickinse0da3822005-04-19 13:29:15 -0700280 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 } while (pud++, addr = next, addr != end);
282
Hugh Dickinse0da3822005-04-19 13:29:15 -0700283 start &= PGDIR_MASK;
284 if (start < floor)
285 return;
286 if (ceiling) {
287 ceiling &= PGDIR_MASK;
288 if (!ceiling)
289 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 }
Hugh Dickinse0da3822005-04-19 13:29:15 -0700291 if (end - 1 > ceiling - 1)
292 return;
293
294 pud = pud_offset(pgd, start);
295 pgd_clear(pgd);
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000296 pud_free_tlb(tlb, pud, start);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297}
298
299/*
Hugh Dickinse0da3822005-04-19 13:29:15 -0700300 * This function frees user-level page tables of a process.
301 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 * Must be called with pagetable lock held.
303 */
Jan Beulich42b77722008-07-23 21:27:10 -0700304void free_pgd_range(struct mmu_gather *tlb,
Hugh Dickinse0da3822005-04-19 13:29:15 -0700305 unsigned long addr, unsigned long end,
306 unsigned long floor, unsigned long ceiling)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307{
308 pgd_t *pgd;
309 unsigned long next;
310
Hugh Dickinse0da3822005-04-19 13:29:15 -0700311 /*
312 * The next few lines have given us lots of grief...
313 *
314 * Why are we testing PMD* at this top level? Because often
315 * there will be no work to do at all, and we'd prefer not to
316 * go all the way down to the bottom just to discover that.
317 *
318 * Why all these "- 1"s? Because 0 represents both the bottom
319 * of the address space and the top of it (using -1 for the
320 * top wouldn't help much: the masks would do the wrong thing).
321 * The rule is that addr 0 and floor 0 refer to the bottom of
322 * the address space, but end 0 and ceiling 0 refer to the top
323 * Comparisons need to use "end - 1" and "ceiling - 1" (though
324 * that end 0 case should be mythical).
325 *
326 * Wherever addr is brought up or ceiling brought down, we must
327 * be careful to reject "the opposite 0" before it confuses the
328 * subsequent tests. But what about where end is brought down
329 * by PMD_SIZE below? no, end can't go down to 0 there.
330 *
331 * Whereas we round start (addr) and ceiling down, by different
332 * masks at different levels, in order to test whether a table
333 * now has no other vmas using it, so can be freed, we don't
334 * bother to round floor or end up - the tests don't need that.
335 */
336
337 addr &= PMD_MASK;
338 if (addr < floor) {
339 addr += PMD_SIZE;
340 if (!addr)
341 return;
342 }
343 if (ceiling) {
344 ceiling &= PMD_MASK;
345 if (!ceiling)
346 return;
347 }
348 if (end - 1 > ceiling - 1)
349 end -= PMD_SIZE;
350 if (addr > end - 1)
351 return;
352
Jan Beulich42b77722008-07-23 21:27:10 -0700353 pgd = pgd_offset(tlb->mm, addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 do {
355 next = pgd_addr_end(addr, end);
356 if (pgd_none_or_clear_bad(pgd))
357 continue;
Jan Beulich42b77722008-07-23 21:27:10 -0700358 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 } while (pgd++, addr = next, addr != end);
Hugh Dickinse0da3822005-04-19 13:29:15 -0700360}
361
Jan Beulich42b77722008-07-23 21:27:10 -0700362void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700363 unsigned long floor, unsigned long ceiling)
Hugh Dickinse0da3822005-04-19 13:29:15 -0700364{
365 while (vma) {
366 struct vm_area_struct *next = vma->vm_next;
367 unsigned long addr = vma->vm_start;
368
Hugh Dickins8f4f8c12005-10-29 18:16:29 -0700369 /*
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +1000370 * Hide vma from rmap and truncate_pagecache before freeing
371 * pgtables
Hugh Dickins8f4f8c12005-10-29 18:16:29 -0700372 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800373 unlink_anon_vmas(vma);
Hugh Dickins8f4f8c12005-10-29 18:16:29 -0700374 unlink_file_vma(vma);
375
David Gibson9da61ae2006-03-22 00:08:57 -0800376 if (is_vm_hugetlb_page(vma)) {
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700377 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
Hugh Dickinse0da3822005-04-19 13:29:15 -0700378 floor, next? next->vm_start: ceiling);
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700379 } else {
380 /*
381 * Optimization: gather nearby vmas into one call down
382 */
383 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
David Gibson48669202006-03-22 00:08:58 -0800384 && !is_vm_hugetlb_page(next)) {
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700385 vma = next;
386 next = vma->vm_next;
Rik van Riel5beb4932010-03-05 13:42:07 -0800387 unlink_anon_vmas(vma);
Hugh Dickins8f4f8c12005-10-29 18:16:29 -0700388 unlink_file_vma(vma);
Hugh Dickins3bf5ee92005-04-19 13:29:16 -0700389 }
390 free_pgd_range(tlb, addr, vma->vm_end,
391 floor, next? next->vm_start: ceiling);
392 }
Hugh Dickinse0da3822005-04-19 13:29:15 -0700393 vma = next;
394 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395}
396
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -0800397int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
398 pmd_t *pmd, unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399{
Martin Schwidefsky2f569af2008-02-08 04:22:04 -0800400 pgtable_t new = pte_alloc_one(mm, address);
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -0800401 int wait_split_huge_page;
Hugh Dickins1bb36302005-10-29 18:16:22 -0700402 if (!new)
403 return -ENOMEM;
404
Nick Piggin362a61a2008-05-14 06:37:36 +0200405 /*
406 * Ensure all pte setup (eg. pte page lock and page clearing) are
407 * visible before the pte is made visible to other CPUs by being
408 * put into page tables.
409 *
410 * The other side of the story is the pointer chasing in the page
411 * table walking code (when walking the page table without locking;
412 * ie. most of the time). Fortunately, these data accesses consist
413 * of a chain of data-dependent loads, meaning most CPUs (alpha
414 * being the notable exception) will already guarantee loads are
415 * seen in-order. See the alpha page table accessors for the
416 * smp_read_barrier_depends() barriers in page table walking code.
417 */
418 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
419
Hugh Dickinsc74df322005-10-29 18:16:23 -0700420 spin_lock(&mm->page_table_lock);
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -0800421 wait_split_huge_page = 0;
422 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 mm->nr_ptes++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 pmd_populate(mm, pmd, new);
Martin Schwidefsky2f569af2008-02-08 04:22:04 -0800425 new = NULL;
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -0800426 } else if (unlikely(pmd_trans_splitting(*pmd)))
427 wait_split_huge_page = 1;
Hugh Dickinsc74df322005-10-29 18:16:23 -0700428 spin_unlock(&mm->page_table_lock);
Martin Schwidefsky2f569af2008-02-08 04:22:04 -0800429 if (new)
430 pte_free(mm, new);
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -0800431 if (wait_split_huge_page)
432 wait_split_huge_page(vma->anon_vma, pmd);
Hugh Dickins1bb36302005-10-29 18:16:22 -0700433 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434}
435
Hugh Dickins1bb36302005-10-29 18:16:22 -0700436int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437{
Hugh Dickins1bb36302005-10-29 18:16:22 -0700438 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
439 if (!new)
440 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441
Nick Piggin362a61a2008-05-14 06:37:36 +0200442 smp_wmb(); /* See comment in __pte_alloc */
443
Hugh Dickins1bb36302005-10-29 18:16:22 -0700444 spin_lock(&init_mm.page_table_lock);
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -0800445 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
Hugh Dickins1bb36302005-10-29 18:16:22 -0700446 pmd_populate_kernel(&init_mm, pmd, new);
Martin Schwidefsky2f569af2008-02-08 04:22:04 -0800447 new = NULL;
Andrea Arcangeli8ac1f832011-01-13 15:46:43 -0800448 } else
449 VM_BUG_ON(pmd_trans_splitting(*pmd));
Hugh Dickins1bb36302005-10-29 18:16:22 -0700450 spin_unlock(&init_mm.page_table_lock);
Martin Schwidefsky2f569af2008-02-08 04:22:04 -0800451 if (new)
452 pte_free_kernel(&init_mm, new);
Hugh Dickins1bb36302005-10-29 18:16:22 -0700453 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454}
455
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800456static inline void init_rss_vec(int *rss)
Hugh Dickinsae859762005-10-29 18:16:05 -0700457{
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800458 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
459}
460
461static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
462{
463 int i;
464
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -0800465 if (current->mm == mm)
466 sync_mm_rss(current, mm);
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800467 for (i = 0; i < NR_MM_COUNTERS; i++)
468 if (rss[i])
469 add_mm_counter(mm, i, rss[i]);
Hugh Dickinsae859762005-10-29 18:16:05 -0700470}
471
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472/*
Linus Torvalds6aab3412005-11-28 14:34:23 -0800473 * This function is called to print an error when a bad pte
474 * is found. For example, we might have a PFN-mapped pte in
475 * a region that doesn't allow it.
Nick Pigginb5810032005-10-29 18:16:12 -0700476 *
477 * The calling function must still handle the error.
478 */
Hugh Dickins3dc14742009-01-06 14:40:08 -0800479static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
480 pte_t pte, struct page *page)
Nick Pigginb5810032005-10-29 18:16:12 -0700481{
Hugh Dickins3dc14742009-01-06 14:40:08 -0800482 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
483 pud_t *pud = pud_offset(pgd, addr);
484 pmd_t *pmd = pmd_offset(pud, addr);
485 struct address_space *mapping;
486 pgoff_t index;
Hugh Dickinsd936cf92009-01-06 14:40:12 -0800487 static unsigned long resume;
488 static unsigned long nr_shown;
489 static unsigned long nr_unshown;
490
491 /*
492 * Allow a burst of 60 reports, then keep quiet for that minute;
493 * or allow a steady drip of one report per second.
494 */
495 if (nr_shown == 60) {
496 if (time_before(jiffies, resume)) {
497 nr_unshown++;
498 return;
499 }
500 if (nr_unshown) {
Hugh Dickins1e9e6362009-01-06 14:40:13 -0800501 printk(KERN_ALERT
502 "BUG: Bad page map: %lu messages suppressed\n",
Hugh Dickinsd936cf92009-01-06 14:40:12 -0800503 nr_unshown);
504 nr_unshown = 0;
505 }
506 nr_shown = 0;
507 }
508 if (nr_shown++ == 0)
509 resume = jiffies + 60 * HZ;
Hugh Dickins3dc14742009-01-06 14:40:08 -0800510
511 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
512 index = linear_page_index(vma, addr);
513
Hugh Dickins1e9e6362009-01-06 14:40:13 -0800514 printk(KERN_ALERT
515 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
Hugh Dickins3dc14742009-01-06 14:40:08 -0800516 current->comm,
517 (long long)pte_val(pte), (long long)pmd_val(*pmd));
Wu Fengguang718a3822010-03-10 15:20:43 -0800518 if (page)
519 dump_page(page);
Hugh Dickins1e9e6362009-01-06 14:40:13 -0800520 printk(KERN_ALERT
Hugh Dickins3dc14742009-01-06 14:40:08 -0800521 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
522 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
523 /*
524 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
525 */
526 if (vma->vm_ops)
Hugh Dickins1e9e6362009-01-06 14:40:13 -0800527 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
Hugh Dickins3dc14742009-01-06 14:40:08 -0800528 (unsigned long)vma->vm_ops->fault);
529 if (vma->vm_file && vma->vm_file->f_op)
Hugh Dickins1e9e6362009-01-06 14:40:13 -0800530 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
Hugh Dickins3dc14742009-01-06 14:40:08 -0800531 (unsigned long)vma->vm_file->f_op->mmap);
Nick Pigginb5810032005-10-29 18:16:12 -0700532 dump_stack();
Hugh Dickins3dc14742009-01-06 14:40:08 -0800533 add_taint(TAINT_BAD_PAGE);
Nick Pigginb5810032005-10-29 18:16:12 -0700534}
535
Linus Torvalds67121172005-12-11 20:38:17 -0800536static inline int is_cow_mapping(unsigned int flags)
537{
538 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
539}
540
Hugh Dickins62eede62009-09-21 17:03:34 -0700541#ifndef is_zero_pfn
542static inline int is_zero_pfn(unsigned long pfn)
543{
544 return pfn == zero_pfn;
545}
546#endif
547
548#ifndef my_zero_pfn
549static inline unsigned long my_zero_pfn(unsigned long addr)
550{
551 return zero_pfn;
552}
553#endif
554
Nick Pigginb5810032005-10-29 18:16:12 -0700555/*
Nick Piggin7e675132008-04-28 02:13:00 -0700556 * vm_normal_page -- This function gets the "struct page" associated with a pte.
Linus Torvalds6aab3412005-11-28 14:34:23 -0800557 *
Nick Piggin7e675132008-04-28 02:13:00 -0700558 * "Special" mappings do not wish to be associated with a "struct page" (either
559 * it doesn't exist, or it exists but they don't want to touch it). In this
560 * case, NULL is returned here. "Normal" mappings do have a struct page.
Jared Hulbertb379d792008-04-28 02:12:58 -0700561 *
Nick Piggin7e675132008-04-28 02:13:00 -0700562 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
563 * pte bit, in which case this function is trivial. Secondly, an architecture
564 * may not have a spare pte bit, which requires a more complicated scheme,
565 * described below.
566 *
567 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
568 * special mapping (even if there are underlying and valid "struct pages").
569 * COWed pages of a VM_PFNMAP are always normal.
Linus Torvalds6aab3412005-11-28 14:34:23 -0800570 *
Jared Hulbertb379d792008-04-28 02:12:58 -0700571 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
572 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
Nick Piggin7e675132008-04-28 02:13:00 -0700573 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
574 * mapping will always honor the rule
Linus Torvalds6aab3412005-11-28 14:34:23 -0800575 *
576 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
577 *
Nick Piggin7e675132008-04-28 02:13:00 -0700578 * And for normal mappings this is false.
Jared Hulbertb379d792008-04-28 02:12:58 -0700579 *
Nick Piggin7e675132008-04-28 02:13:00 -0700580 * This restricts such mappings to be a linear translation from virtual address
581 * to pfn. To get around this restriction, we allow arbitrary mappings so long
582 * as the vma is not a COW mapping; in that case, we know that all ptes are
583 * special (because none can have been COWed).
Jared Hulbertb379d792008-04-28 02:12:58 -0700584 *
585 *
Nick Piggin7e675132008-04-28 02:13:00 -0700586 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
587 *
Jared Hulbertb379d792008-04-28 02:12:58 -0700588 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
589 * page" backing, however the difference is that _all_ pages with a struct
590 * page (that is, those where pfn_valid is true) are refcounted and considered
591 * normal pages by the VM. The disadvantage is that pages are refcounted
592 * (which can be slower and simply not an option for some PFNMAP users). The
593 * advantage is that we don't have to follow the strict linearity rule of
594 * PFNMAP mappings in order to support COWable mappings.
595 *
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800596 */
Nick Piggin7e675132008-04-28 02:13:00 -0700597#ifdef __HAVE_ARCH_PTE_SPECIAL
598# define HAVE_PTE_SPECIAL 1
599#else
600# define HAVE_PTE_SPECIAL 0
601#endif
602struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
603 pte_t pte)
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800604{
Hugh Dickins22b31ee2009-01-06 14:40:09 -0800605 unsigned long pfn = pte_pfn(pte);
Nick Piggin7e675132008-04-28 02:13:00 -0700606
607 if (HAVE_PTE_SPECIAL) {
Hugh Dickins22b31ee2009-01-06 14:40:09 -0800608 if (likely(!pte_special(pte)))
609 goto check_pfn;
Hugh Dickinsa13ea5b2009-09-21 17:03:30 -0700610 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
611 return NULL;
Hugh Dickins62eede62009-09-21 17:03:34 -0700612 if (!is_zero_pfn(pfn))
Hugh Dickins22b31ee2009-01-06 14:40:09 -0800613 print_bad_pte(vma, addr, pte, NULL);
Nick Piggin7e675132008-04-28 02:13:00 -0700614 return NULL;
615 }
616
617 /* !HAVE_PTE_SPECIAL case follows: */
618
Jared Hulbertb379d792008-04-28 02:12:58 -0700619 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
620 if (vma->vm_flags & VM_MIXEDMAP) {
621 if (!pfn_valid(pfn))
622 return NULL;
623 goto out;
624 } else {
Nick Piggin7e675132008-04-28 02:13:00 -0700625 unsigned long off;
626 off = (addr - vma->vm_start) >> PAGE_SHIFT;
Jared Hulbertb379d792008-04-28 02:12:58 -0700627 if (pfn == vma->vm_pgoff + off)
628 return NULL;
629 if (!is_cow_mapping(vma->vm_flags))
630 return NULL;
631 }
Linus Torvalds6aab3412005-11-28 14:34:23 -0800632 }
633
Hugh Dickins62eede62009-09-21 17:03:34 -0700634 if (is_zero_pfn(pfn))
635 return NULL;
Hugh Dickins22b31ee2009-01-06 14:40:09 -0800636check_pfn:
637 if (unlikely(pfn > highest_memmap_pfn)) {
638 print_bad_pte(vma, addr, pte, NULL);
639 return NULL;
640 }
Linus Torvalds6aab3412005-11-28 14:34:23 -0800641
642 /*
Nick Piggin7e675132008-04-28 02:13:00 -0700643 * NOTE! We still have PageReserved() pages in the page tables.
Nick Piggin7e675132008-04-28 02:13:00 -0700644 * eg. VDSO mappings can cause them to exist.
Linus Torvalds6aab3412005-11-28 14:34:23 -0800645 */
Jared Hulbertb379d792008-04-28 02:12:58 -0700646out:
Linus Torvalds6aab3412005-11-28 14:34:23 -0800647 return pfn_to_page(pfn);
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800648}
649
650/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 * copy one vm_area from one task to the other. Assumes the page tables
652 * already present in the new task to be cleared in the whole range
653 * covered by this vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654 */
655
Hugh Dickins570a3352009-12-14 17:58:46 -0800656static inline unsigned long
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
Nick Pigginb5810032005-10-29 18:16:12 -0700658 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
Hugh Dickins8c103762005-10-29 18:16:13 -0700659 unsigned long addr, int *rss)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660{
Nick Pigginb5810032005-10-29 18:16:12 -0700661 unsigned long vm_flags = vma->vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 pte_t pte = *src_pte;
663 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664
665 /* pte contains position in swap or file, so copy. */
666 if (unlikely(!pte_present(pte))) {
667 if (!pte_file(pte)) {
Christoph Lameter06972122006-06-23 02:03:35 -0700668 swp_entry_t entry = pte_to_swp_entry(pte);
669
Hugh Dickins570a3352009-12-14 17:58:46 -0800670 if (swap_duplicate(entry) < 0)
671 return entry.val;
672
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 /* make sure dst_mm is on swapoff's mmlist. */
674 if (unlikely(list_empty(&dst_mm->mmlist))) {
675 spin_lock(&mmlist_lock);
Hugh Dickinsf412ac02005-10-29 18:16:41 -0700676 if (list_empty(&dst_mm->mmlist))
677 list_add(&dst_mm->mmlist,
678 &src_mm->mmlist);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 spin_unlock(&mmlist_lock);
680 }
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -0800681 if (likely(!non_swap_entry(entry)))
682 rss[MM_SWAPENTS]++;
683 else if (is_write_migration_entry(entry) &&
Christoph Lameter06972122006-06-23 02:03:35 -0700684 is_cow_mapping(vm_flags)) {
685 /*
686 * COW mappings require pages in both parent
687 * and child to be set to read.
688 */
689 make_migration_entry_read(&entry);
690 pte = swp_entry_to_pte(entry);
691 set_pte_at(src_mm, addr, src_pte, pte);
692 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 }
Hugh Dickinsae859762005-10-29 18:16:05 -0700694 goto out_set_pte;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 }
696
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 /*
698 * If it's a COW mapping, write protect it both
699 * in the parent and the child
700 */
Linus Torvalds67121172005-12-11 20:38:17 -0800701 if (is_cow_mapping(vm_flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 ptep_set_wrprotect(src_mm, addr, src_pte);
Zachary Amsden3dc90792006-09-30 23:29:30 -0700703 pte = pte_wrprotect(pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704 }
705
706 /*
707 * If it's a shared mapping, mark it clean in
708 * the child
709 */
710 if (vm_flags & VM_SHARED)
711 pte = pte_mkclean(pte);
712 pte = pte_mkold(pte);
Linus Torvalds6aab3412005-11-28 14:34:23 -0800713
714 page = vm_normal_page(vma, addr, pte);
715 if (page) {
716 get_page(page);
Hugh Dickins21333b22009-09-21 17:01:59 -0700717 page_dup_rmap(page);
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800718 if (PageAnon(page))
719 rss[MM_ANONPAGES]++;
720 else
721 rss[MM_FILEPAGES]++;
Linus Torvalds6aab3412005-11-28 14:34:23 -0800722 }
Hugh Dickinsae859762005-10-29 18:16:05 -0700723
724out_set_pte:
725 set_pte_at(dst_mm, addr, dst_pte, pte);
Hugh Dickins570a3352009-12-14 17:58:46 -0800726 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727}
728
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800729int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
730 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
731 unsigned long addr, unsigned long end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732{
Daisuke Nishimurac36987e2009-10-26 16:50:23 -0700733 pte_t *orig_src_pte, *orig_dst_pte;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 pte_t *src_pte, *dst_pte;
Hugh Dickinsc74df322005-10-29 18:16:23 -0700735 spinlock_t *src_ptl, *dst_ptl;
Hugh Dickinse040f212005-10-29 18:15:53 -0700736 int progress = 0;
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800737 int rss[NR_MM_COUNTERS];
Hugh Dickins570a3352009-12-14 17:58:46 -0800738 swp_entry_t entry = (swp_entry_t){0};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739
740again:
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800741 init_rss_vec(rss);
742
Hugh Dickinsc74df322005-10-29 18:16:23 -0700743 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 if (!dst_pte)
745 return -ENOMEM;
Peter Zijlstraece0e2b2010-10-26 14:21:52 -0700746 src_pte = pte_offset_map(src_pmd, addr);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700747 src_ptl = pte_lockptr(src_mm, src_pmd);
Ingo Molnarf20dc5f2006-07-03 00:25:08 -0700748 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
Daisuke Nishimurac36987e2009-10-26 16:50:23 -0700749 orig_src_pte = src_pte;
750 orig_dst_pte = dst_pte;
Zachary Amsden6606c3e2006-09-30 23:29:33 -0700751 arch_enter_lazy_mmu_mode();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 do {
754 /*
755 * We are holding two locks at this point - either of them
756 * could generate latencies in another task on another CPU.
757 */
Hugh Dickinse040f212005-10-29 18:15:53 -0700758 if (progress >= 32) {
759 progress = 0;
760 if (need_resched() ||
Nick Piggin95c354f2008-01-30 13:31:20 +0100761 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
Hugh Dickinse040f212005-10-29 18:15:53 -0700762 break;
763 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 if (pte_none(*src_pte)) {
765 progress++;
766 continue;
767 }
Hugh Dickins570a3352009-12-14 17:58:46 -0800768 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
769 vma, addr, rss);
770 if (entry.val)
771 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700772 progress += 8;
773 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774
Zachary Amsden6606c3e2006-09-30 23:29:33 -0700775 arch_leave_lazy_mmu_mode();
Hugh Dickinsc74df322005-10-29 18:16:23 -0700776 spin_unlock(src_ptl);
Peter Zijlstraece0e2b2010-10-26 14:21:52 -0700777 pte_unmap(orig_src_pte);
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800778 add_mm_rss_vec(dst_mm, rss);
Daisuke Nishimurac36987e2009-10-26 16:50:23 -0700779 pte_unmap_unlock(orig_dst_pte, dst_ptl);
Hugh Dickinsc74df322005-10-29 18:16:23 -0700780 cond_resched();
Hugh Dickins570a3352009-12-14 17:58:46 -0800781
782 if (entry.val) {
783 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
784 return -ENOMEM;
785 progress = 0;
786 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787 if (addr != end)
788 goto again;
789 return 0;
790}
791
792static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
793 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
794 unsigned long addr, unsigned long end)
795{
796 pmd_t *src_pmd, *dst_pmd;
797 unsigned long next;
798
799 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
800 if (!dst_pmd)
801 return -ENOMEM;
802 src_pmd = pmd_offset(src_pud, addr);
803 do {
804 next = pmd_addr_end(addr, end);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800805 if (pmd_trans_huge(*src_pmd)) {
806 int err;
Andrea Arcangeli14d1a552011-01-13 15:47:15 -0800807 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800808 err = copy_huge_pmd(dst_mm, src_mm,
809 dst_pmd, src_pmd, addr, vma);
810 if (err == -ENOMEM)
811 return -ENOMEM;
812 if (!err)
813 continue;
814 /* fall through */
815 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 if (pmd_none_or_clear_bad(src_pmd))
817 continue;
818 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
819 vma, addr, next))
820 return -ENOMEM;
821 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
822 return 0;
823}
824
825static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
826 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
827 unsigned long addr, unsigned long end)
828{
829 pud_t *src_pud, *dst_pud;
830 unsigned long next;
831
832 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
833 if (!dst_pud)
834 return -ENOMEM;
835 src_pud = pud_offset(src_pgd, addr);
836 do {
837 next = pud_addr_end(addr, end);
838 if (pud_none_or_clear_bad(src_pud))
839 continue;
840 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
841 vma, addr, next))
842 return -ENOMEM;
843 } while (dst_pud++, src_pud++, addr = next, addr != end);
844 return 0;
845}
846
847int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
848 struct vm_area_struct *vma)
849{
850 pgd_t *src_pgd, *dst_pgd;
851 unsigned long next;
852 unsigned long addr = vma->vm_start;
853 unsigned long end = vma->vm_end;
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700854 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855
Nick Piggind9928952005-08-28 16:49:11 +1000856 /*
857 * Don't copy ptes where a page fault will fill them correctly.
858 * Fork becomes much lighter when there are big shared or private
859 * readonly mappings. The tradeoff is that copy_page_range is more
860 * efficient than faulting.
861 */
Linus Torvalds4d7672b2005-12-16 10:21:23 -0800862 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
Nick Piggind9928952005-08-28 16:49:11 +1000863 if (!vma->anon_vma)
864 return 0;
865 }
866
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867 if (is_vm_hugetlb_page(vma))
868 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
869
venkatesh.pallipadi@intel.com34801ba2008-12-19 13:47:29 -0800870 if (unlikely(is_pfn_mapping(vma))) {
venkatesh.pallipadi@intel.com2ab64032008-12-18 11:41:29 -0800871 /*
872 * We do not free on error cases below as remove_vma
873 * gets called on error from higher level routine
874 */
875 ret = track_pfn_vma_copy(vma);
876 if (ret)
877 return ret;
878 }
879
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700880 /*
881 * We need to invalidate the secondary MMU mappings only when
882 * there could be a permission downgrade on the ptes of the
883 * parent mm. And a permission downgrade will only happen if
884 * is_cow_mapping() returns true.
885 */
886 if (is_cow_mapping(vma->vm_flags))
887 mmu_notifier_invalidate_range_start(src_mm, addr, end);
888
889 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700890 dst_pgd = pgd_offset(dst_mm, addr);
891 src_pgd = pgd_offset(src_mm, addr);
892 do {
893 next = pgd_addr_end(addr, end);
894 if (pgd_none_or_clear_bad(src_pgd))
895 continue;
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700896 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
897 vma, addr, next))) {
898 ret = -ENOMEM;
899 break;
900 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700902
903 if (is_cow_mapping(vma->vm_flags))
904 mmu_notifier_invalidate_range_end(src_mm,
905 vma->vm_start, end);
906 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907}
908
Robin Holt51c6f662005-11-13 16:06:42 -0800909static unsigned long zap_pte_range(struct mmu_gather *tlb,
Nick Pigginb5810032005-10-29 18:16:12 -0700910 struct vm_area_struct *vma, pmd_t *pmd,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 unsigned long addr, unsigned long end,
Robin Holt51c6f662005-11-13 16:06:42 -0800912 long *zap_work, struct zap_details *details)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913{
Nick Pigginb5810032005-10-29 18:16:12 -0700914 struct mm_struct *mm = tlb->mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 pte_t *pte;
Hugh Dickins508034a2005-10-29 18:16:30 -0700916 spinlock_t *ptl;
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800917 int rss[NR_MM_COUNTERS];
918
919 init_rss_vec(rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920
Hugh Dickins508034a2005-10-29 18:16:30 -0700921 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
Zachary Amsden6606c3e2006-09-30 23:29:33 -0700922 arch_enter_lazy_mmu_mode();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 do {
924 pte_t ptent = *pte;
Robin Holt51c6f662005-11-13 16:06:42 -0800925 if (pte_none(ptent)) {
926 (*zap_work)--;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700927 continue;
Robin Holt51c6f662005-11-13 16:06:42 -0800928 }
Hugh Dickins6f5e6b92006-03-16 23:04:09 -0800929
930 (*zap_work) -= PAGE_SIZE;
931
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932 if (pte_present(ptent)) {
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800933 struct page *page;
Robin Holt51c6f662005-11-13 16:06:42 -0800934
Linus Torvalds6aab3412005-11-28 14:34:23 -0800935 page = vm_normal_page(vma, addr, ptent);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936 if (unlikely(details) && page) {
937 /*
938 * unmap_shared_mapping_pages() wants to
939 * invalidate cache without truncating:
940 * unmap shared but keep private pages.
941 */
942 if (details->check_mapping &&
943 details->check_mapping != page->mapping)
944 continue;
945 /*
946 * Each page->index must be checked when
947 * invalidating or truncating nonlinear.
948 */
949 if (details->nonlinear_vma &&
950 (page->index < details->first_index ||
951 page->index > details->last_index))
952 continue;
953 }
Nick Pigginb5810032005-10-29 18:16:12 -0700954 ptent = ptep_get_and_clear_full(mm, addr, pte,
Zachary Amsdena6003882005-09-03 15:55:04 -0700955 tlb->fullmm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956 tlb_remove_tlb_entry(tlb, pte, addr);
957 if (unlikely(!page))
958 continue;
959 if (unlikely(details) && details->nonlinear_vma
960 && linear_page_index(details->nonlinear_vma,
961 addr) != page->index)
Nick Pigginb5810032005-10-29 18:16:12 -0700962 set_pte_at(mm, addr, pte,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700963 pgoff_to_pte(page->index));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964 if (PageAnon(page))
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800965 rss[MM_ANONPAGES]--;
Hugh Dickins6237bcd2005-10-29 18:15:54 -0700966 else {
967 if (pte_dirty(ptent))
968 set_page_dirty(page);
Johannes Weiner4917e5d2009-01-06 14:39:17 -0800969 if (pte_young(ptent) &&
970 likely(!VM_SequentialReadHint(vma)))
Nick Pigginbf3f3bc2009-01-06 14:38:55 -0800971 mark_page_accessed(page);
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -0800972 rss[MM_FILEPAGES]--;
Hugh Dickins6237bcd2005-10-29 18:15:54 -0700973 }
Hugh Dickinsedc315f2009-01-06 14:40:11 -0800974 page_remove_rmap(page);
Hugh Dickins3dc14742009-01-06 14:40:08 -0800975 if (unlikely(page_mapcount(page) < 0))
976 print_bad_pte(vma, addr, ptent, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977 tlb_remove_page(tlb, page);
978 continue;
979 }
980 /*
981 * If details->check_mapping, we leave swap entries;
982 * if details->nonlinear_vma, we leave file entries.
983 */
984 if (unlikely(details))
985 continue;
Hugh Dickins2509ef22009-01-06 14:40:10 -0800986 if (pte_file(ptent)) {
987 if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
988 print_bad_pte(vma, addr, ptent, NULL);
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -0800989 } else {
990 swp_entry_t entry = pte_to_swp_entry(ptent);
991
992 if (!non_swap_entry(entry))
993 rss[MM_SWAPENTS]--;
994 if (unlikely(!free_swap_and_cache(entry)))
995 print_bad_pte(vma, addr, ptent, NULL);
996 }
Zachary Amsden9888a1c2006-09-30 23:29:31 -0700997 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
Robin Holt51c6f662005-11-13 16:06:42 -0800998 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
Hugh Dickinsae859762005-10-29 18:16:05 -0700999
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001000 add_mm_rss_vec(mm, rss);
Zachary Amsden6606c3e2006-09-30 23:29:33 -07001001 arch_leave_lazy_mmu_mode();
Hugh Dickins508034a2005-10-29 18:16:30 -07001002 pte_unmap_unlock(pte - 1, ptl);
Robin Holt51c6f662005-11-13 16:06:42 -08001003
1004 return addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005}
1006
Robin Holt51c6f662005-11-13 16:06:42 -08001007static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
Nick Pigginb5810032005-10-29 18:16:12 -07001008 struct vm_area_struct *vma, pud_t *pud,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009 unsigned long addr, unsigned long end,
Robin Holt51c6f662005-11-13 16:06:42 -08001010 long *zap_work, struct zap_details *details)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011{
1012 pmd_t *pmd;
1013 unsigned long next;
1014
1015 pmd = pmd_offset(pud, addr);
1016 do {
1017 next = pmd_addr_end(addr, end);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001018 if (pmd_trans_huge(*pmd)) {
Andrea Arcangeli14d1a552011-01-13 15:47:15 -08001019 if (next-addr != HPAGE_PMD_SIZE) {
1020 VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001021 split_huge_page_pmd(vma->vm_mm, pmd);
Andrea Arcangeli14d1a552011-01-13 15:47:15 -08001022 } else if (zap_huge_pmd(tlb, vma, pmd)) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001023 (*zap_work)--;
1024 continue;
1025 }
1026 /* fall through */
1027 }
Robin Holt51c6f662005-11-13 16:06:42 -08001028 if (pmd_none_or_clear_bad(pmd)) {
1029 (*zap_work)--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030 continue;
Robin Holt51c6f662005-11-13 16:06:42 -08001031 }
1032 next = zap_pte_range(tlb, vma, pmd, addr, next,
1033 zap_work, details);
1034 } while (pmd++, addr = next, (addr != end && *zap_work > 0));
1035
1036 return addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037}
1038
Robin Holt51c6f662005-11-13 16:06:42 -08001039static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
Nick Pigginb5810032005-10-29 18:16:12 -07001040 struct vm_area_struct *vma, pgd_t *pgd,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041 unsigned long addr, unsigned long end,
Robin Holt51c6f662005-11-13 16:06:42 -08001042 long *zap_work, struct zap_details *details)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043{
1044 pud_t *pud;
1045 unsigned long next;
1046
1047 pud = pud_offset(pgd, addr);
1048 do {
1049 next = pud_addr_end(addr, end);
Robin Holt51c6f662005-11-13 16:06:42 -08001050 if (pud_none_or_clear_bad(pud)) {
1051 (*zap_work)--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052 continue;
Robin Holt51c6f662005-11-13 16:06:42 -08001053 }
1054 next = zap_pmd_range(tlb, vma, pud, addr, next,
1055 zap_work, details);
1056 } while (pud++, addr = next, (addr != end && *zap_work > 0));
1057
1058 return addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059}
1060
Robin Holt51c6f662005-11-13 16:06:42 -08001061static unsigned long unmap_page_range(struct mmu_gather *tlb,
1062 struct vm_area_struct *vma,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063 unsigned long addr, unsigned long end,
Robin Holt51c6f662005-11-13 16:06:42 -08001064 long *zap_work, struct zap_details *details)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065{
1066 pgd_t *pgd;
1067 unsigned long next;
1068
1069 if (details && !details->check_mapping && !details->nonlinear_vma)
1070 details = NULL;
1071
1072 BUG_ON(addr >= end);
KAMEZAWA Hiroyuki569b8462009-12-15 16:47:03 -08001073 mem_cgroup_uncharge_start();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001074 tlb_start_vma(tlb, vma);
1075 pgd = pgd_offset(vma->vm_mm, addr);
1076 do {
1077 next = pgd_addr_end(addr, end);
Robin Holt51c6f662005-11-13 16:06:42 -08001078 if (pgd_none_or_clear_bad(pgd)) {
1079 (*zap_work)--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080 continue;
Robin Holt51c6f662005-11-13 16:06:42 -08001081 }
1082 next = zap_pud_range(tlb, vma, pgd, addr, next,
1083 zap_work, details);
1084 } while (pgd++, addr = next, (addr != end && *zap_work > 0));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 tlb_end_vma(tlb, vma);
KAMEZAWA Hiroyuki569b8462009-12-15 16:47:03 -08001086 mem_cgroup_uncharge_end();
Robin Holt51c6f662005-11-13 16:06:42 -08001087
1088 return addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089}
1090
1091#ifdef CONFIG_PREEMPT
1092# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
1093#else
1094/* No preempt: go for improved straight-line efficiency */
1095# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
1096#endif
1097
1098/**
1099 * unmap_vmas - unmap a range of memory covered by a list of vma's
1100 * @tlbp: address of the caller's struct mmu_gather
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 * @vma: the starting vma
1102 * @start_addr: virtual address at which to start unmapping
1103 * @end_addr: virtual address at which to end unmapping
1104 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
1105 * @details: details of nonlinear truncation or shared cache invalidation
1106 *
Hugh Dickinsee39b372005-04-19 13:29:15 -07001107 * Returns the end address of the unmapping (restart addr if interrupted).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 *
Hugh Dickins508034a2005-10-29 18:16:30 -07001109 * Unmap all pages in the vma list.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110 *
Hugh Dickins508034a2005-10-29 18:16:30 -07001111 * We aim to not hold locks for too long (for scheduling latency reasons).
1112 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001113 * return the ending mmu_gather to the caller.
1114 *
1115 * Only addresses between `start' and `end' will be unmapped.
1116 *
1117 * The VMA list must be sorted in ascending virtual address order.
1118 *
1119 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1120 * range after unmap_vmas() returns. So the only responsibility here is to
1121 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1122 * drops the lock and schedules.
1123 */
Hugh Dickins508034a2005-10-29 18:16:30 -07001124unsigned long unmap_vmas(struct mmu_gather **tlbp,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 struct vm_area_struct *vma, unsigned long start_addr,
1126 unsigned long end_addr, unsigned long *nr_accounted,
1127 struct zap_details *details)
1128{
Robin Holt51c6f662005-11-13 16:06:42 -08001129 long zap_work = ZAP_BLOCK_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 unsigned long tlb_start = 0; /* For tlb_finish_mmu */
1131 int tlb_start_valid = 0;
Hugh Dickinsee39b372005-04-19 13:29:15 -07001132 unsigned long start = start_addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
Hugh Dickins4d6ddfa2005-10-29 18:16:02 -07001134 int fullmm = (*tlbp)->fullmm;
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001135 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001137 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139 unsigned long end;
1140
1141 start = max(vma->vm_start, start_addr);
1142 if (start >= vma->vm_end)
1143 continue;
1144 end = min(vma->vm_end, end_addr);
1145 if (end <= vma->vm_start)
1146 continue;
1147
1148 if (vma->vm_flags & VM_ACCOUNT)
1149 *nr_accounted += (end - start) >> PAGE_SHIFT;
1150
venkatesh.pallipadi@intel.com34801ba2008-12-19 13:47:29 -08001151 if (unlikely(is_pfn_mapping(vma)))
venkatesh.pallipadi@intel.com2ab64032008-12-18 11:41:29 -08001152 untrack_pfn_vma(vma, 0, 0);
1153
Linus Torvalds1da177e2005-04-16 15:20:36 -07001154 while (start != end) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001155 if (!tlb_start_valid) {
1156 tlb_start = start;
1157 tlb_start_valid = 1;
1158 }
1159
Robin Holt51c6f662005-11-13 16:06:42 -08001160 if (unlikely(is_vm_hugetlb_page(vma))) {
Andi Kleena137e1c2008-07-23 21:27:43 -07001161 /*
1162 * It is undesirable to test vma->vm_file as it
1163 * should be non-null for valid hugetlb area.
1164 * However, vm_file will be NULL in the error
1165 * cleanup path of do_mmap_pgoff. When
1166 * hugetlbfs ->mmap method fails,
1167 * do_mmap_pgoff() nullifies vma->vm_file
1168 * before calling this function to clean up.
1169 * Since no pte has actually been setup, it is
1170 * safe to do nothing in this case.
1171 */
1172 if (vma->vm_file) {
1173 unmap_hugepage_range(vma, start, end, NULL);
1174 zap_work -= (end - start) /
Andi Kleena5516432008-07-23 21:27:41 -07001175 pages_per_huge_page(hstate_vma(vma));
Andi Kleena137e1c2008-07-23 21:27:43 -07001176 }
1177
Robin Holt51c6f662005-11-13 16:06:42 -08001178 start = end;
1179 } else
1180 start = unmap_page_range(*tlbp, vma,
1181 start, end, &zap_work, details);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001182
Robin Holt51c6f662005-11-13 16:06:42 -08001183 if (zap_work > 0) {
1184 BUG_ON(start != end);
1185 break;
1186 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187
1188 tlb_finish_mmu(*tlbp, tlb_start, start);
1189
1190 if (need_resched() ||
Nick Piggin95c354f2008-01-30 13:31:20 +01001191 (i_mmap_lock && spin_needbreak(i_mmap_lock))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192 if (i_mmap_lock) {
Hugh Dickins508034a2005-10-29 18:16:30 -07001193 *tlbp = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194 goto out;
1195 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197 }
1198
Hugh Dickins508034a2005-10-29 18:16:30 -07001199 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200 tlb_start_valid = 0;
Robin Holt51c6f662005-11-13 16:06:42 -08001201 zap_work = ZAP_BLOCK_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001202 }
1203 }
1204out:
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001205 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
Hugh Dickinsee39b372005-04-19 13:29:15 -07001206 return start; /* which is now the end (or restart) address */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207}
1208
1209/**
1210 * zap_page_range - remove user pages in a given range
1211 * @vma: vm_area_struct holding the applicable pages
1212 * @address: starting address of pages to zap
1213 * @size: number of bytes to zap
1214 * @details: details of nonlinear truncation or shared cache invalidation
1215 */
Hugh Dickinsee39b372005-04-19 13:29:15 -07001216unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217 unsigned long size, struct zap_details *details)
1218{
1219 struct mm_struct *mm = vma->vm_mm;
1220 struct mmu_gather *tlb;
1221 unsigned long end = address + size;
1222 unsigned long nr_accounted = 0;
1223
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224 lru_add_drain();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225 tlb = tlb_gather_mmu(mm, 0);
Hugh Dickins365e9c872005-10-29 18:16:18 -07001226 update_hiwater_rss(mm);
Hugh Dickins508034a2005-10-29 18:16:30 -07001227 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
1228 if (tlb)
1229 tlb_finish_mmu(tlb, address, end);
Hugh Dickinsee39b372005-04-19 13:29:15 -07001230 return end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001231}
1232
Jack Steinerc627f9c2008-07-29 22:33:53 -07001233/**
1234 * zap_vma_ptes - remove ptes mapping the vma
1235 * @vma: vm_area_struct holding ptes to be zapped
1236 * @address: starting address of pages to zap
1237 * @size: number of bytes to zap
1238 *
1239 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1240 *
1241 * The entire address range must be fully contained within the vma.
1242 *
1243 * Returns 0 if successful.
1244 */
1245int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1246 unsigned long size)
1247{
1248 if (address < vma->vm_start || address + size > vma->vm_end ||
1249 !(vma->vm_flags & VM_PFNMAP))
1250 return -1;
1251 zap_page_range(vma, address, size, NULL);
1252 return 0;
1253}
1254EXPORT_SYMBOL_GPL(zap_vma_ptes);
1255
Johannes Weiner142762b2010-05-24 14:32:39 -07001256/**
1257 * follow_page - look up a page descriptor from a user-virtual address
1258 * @vma: vm_area_struct mapping @address
1259 * @address: virtual address to look up
1260 * @flags: flags modifying lookup behaviour
1261 *
1262 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1263 *
1264 * Returns the mapped (struct page *), %NULL if no mapping exists, or
1265 * an error pointer if there is a mapping to something not represented
1266 * by a page descriptor (see also vm_normal_page()).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001267 */
Linus Torvalds6aab3412005-11-28 14:34:23 -08001268struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001269 unsigned int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270{
1271 pgd_t *pgd;
1272 pud_t *pud;
1273 pmd_t *pmd;
1274 pte_t *ptep, pte;
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001275 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276 struct page *page;
Linus Torvalds6aab3412005-11-28 14:34:23 -08001277 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001279 page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1280 if (!IS_ERR(page)) {
1281 BUG_ON(flags & FOLL_GET);
1282 goto out;
1283 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001285 page = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 pgd = pgd_offset(mm, address);
1287 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001288 goto no_page_table;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289
1290 pud = pud_offset(pgd, address);
Andi Kleenceb86872008-07-23 21:27:50 -07001291 if (pud_none(*pud))
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001292 goto no_page_table;
Hugh Dickins8a076512011-01-13 15:46:52 -08001293 if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
Andi Kleenceb86872008-07-23 21:27:50 -07001294 BUG_ON(flags & FOLL_GET);
1295 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1296 goto out;
1297 }
1298 if (unlikely(pud_bad(*pud)))
1299 goto no_page_table;
1300
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301 pmd = pmd_offset(pud, address);
Hugh Dickinsaeed5fc2008-05-06 20:49:23 +01001302 if (pmd_none(*pmd))
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001303 goto no_page_table;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001304 if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001305 BUG_ON(flags & FOLL_GET);
1306 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1307 goto out;
1308 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001309 if (pmd_trans_huge(*pmd)) {
Andrea Arcangeli500d65d2011-01-13 15:46:55 -08001310 if (flags & FOLL_SPLIT) {
1311 split_huge_page_pmd(mm, pmd);
1312 goto split_fallthrough;
1313 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001314 spin_lock(&mm->page_table_lock);
1315 if (likely(pmd_trans_huge(*pmd))) {
1316 if (unlikely(pmd_trans_splitting(*pmd))) {
1317 spin_unlock(&mm->page_table_lock);
1318 wait_split_huge_page(vma->anon_vma, pmd);
1319 } else {
1320 page = follow_trans_huge_pmd(mm, address,
1321 pmd, flags);
1322 spin_unlock(&mm->page_table_lock);
1323 goto out;
1324 }
1325 } else
1326 spin_unlock(&mm->page_table_lock);
1327 /* fall through */
1328 }
Andrea Arcangeli500d65d2011-01-13 15:46:55 -08001329split_fallthrough:
Hugh Dickinsaeed5fc2008-05-06 20:49:23 +01001330 if (unlikely(pmd_bad(*pmd)))
1331 goto no_page_table;
1332
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001333 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334
1335 pte = *ptep;
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001336 if (!pte_present(pte))
Linus Torvalds89f5b7d2008-06-20 11:18:25 -07001337 goto no_page;
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001338 if ((flags & FOLL_WRITE) && !pte_write(pte))
1339 goto unlock;
Hugh Dickinsa13ea5b2009-09-21 17:03:30 -07001340
Linus Torvalds6aab3412005-11-28 14:34:23 -08001341 page = vm_normal_page(vma, address, pte);
Hugh Dickinsa13ea5b2009-09-21 17:03:30 -07001342 if (unlikely(!page)) {
1343 if ((flags & FOLL_DUMP) ||
Hugh Dickins62eede62009-09-21 17:03:34 -07001344 !is_zero_pfn(pte_pfn(pte)))
Hugh Dickinsa13ea5b2009-09-21 17:03:30 -07001345 goto bad_page;
1346 page = pte_page(pte);
1347 }
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001348
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001349 if (flags & FOLL_GET)
1350 get_page(page);
1351 if (flags & FOLL_TOUCH) {
1352 if ((flags & FOLL_WRITE) &&
1353 !pte_dirty(pte) && !PageDirty(page))
1354 set_page_dirty(page);
KOSAKI Motohirobd775c42009-03-31 15:19:37 -07001355 /*
1356 * pte_mkyoung() would be more correct here, but atomic care
1357 * is needed to avoid losing the dirty bit: it is easier to use
1358 * mark_page_accessed().
1359 */
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001360 mark_page_accessed(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 }
Michel Lespinasse110d74a2011-01-13 15:46:11 -08001362 if (flags & FOLL_MLOCK) {
1363 /*
1364 * The preliminary mapping check is mainly to avoid the
1365 * pointless overhead of lock_page on the ZERO_PAGE
1366 * which might bounce very badly if there is contention.
1367 *
1368 * If the page is already locked, we don't need to
1369 * handle it now - vmscan will handle it later if and
1370 * when it attempts to reclaim the page.
1371 */
1372 if (page->mapping && trylock_page(page)) {
1373 lru_add_drain(); /* push cached pages to LRU */
1374 /*
1375 * Because we lock page here and migration is
1376 * blocked by the pte's page reference, we need
1377 * only check for file-cache page truncation.
1378 */
1379 if (page->mapping)
1380 mlock_vma_page(page);
1381 unlock_page(page);
1382 }
1383 }
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001384unlock:
1385 pte_unmap_unlock(ptep, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386out:
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001387 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388
Linus Torvalds89f5b7d2008-06-20 11:18:25 -07001389bad_page:
1390 pte_unmap_unlock(ptep, ptl);
1391 return ERR_PTR(-EFAULT);
1392
1393no_page:
1394 pte_unmap_unlock(ptep, ptl);
1395 if (!pte_none(pte))
1396 return page;
Hugh Dickins8e4b9a62009-09-21 17:03:26 -07001397
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001398no_page_table:
1399 /*
1400 * When core dumping an enormous anonymous area that nobody
Hugh Dickins8e4b9a62009-09-21 17:03:26 -07001401 * has touched so far, we don't want to allocate unnecessary pages or
1402 * page tables. Return error instead of NULL to skip handle_mm_fault,
1403 * then get_dump_page() will return NULL to leave a hole in the dump.
1404 * But we can only make this optimization where a hole would surely
1405 * be zero-filled if handle_mm_fault() actually did handle it.
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001406 */
Hugh Dickins8e4b9a62009-09-21 17:03:26 -07001407 if ((flags & FOLL_DUMP) &&
1408 (!vma->vm_ops || !vma->vm_ops->fault))
1409 return ERR_PTR(-EFAULT);
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001410 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411}
1412
Linus Torvalds95042f92011-04-12 14:15:51 -07001413static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1414{
1415 return (vma->vm_flags & VM_GROWSDOWN) &&
1416 (vma->vm_start == addr) &&
1417 !vma_stack_continue(vma->vm_prev, addr);
1418}
1419
Huang Ying0014bd92011-01-30 11:15:47 +08001420/**
1421 * __get_user_pages() - pin user pages in memory
1422 * @tsk: task_struct of target task
1423 * @mm: mm_struct of target mm
1424 * @start: starting user address
1425 * @nr_pages: number of pages from start to pin
1426 * @gup_flags: flags modifying pin behaviour
1427 * @pages: array that receives pointers to the pages pinned.
1428 * Should be at least nr_pages long. Or NULL, if caller
1429 * only intends to ensure the pages are faulted in.
1430 * @vmas: array of pointers to vmas corresponding to each page.
1431 * Or NULL if the caller does not require them.
1432 * @nonblocking: whether waiting for disk IO or mmap_sem contention
1433 *
1434 * Returns number of pages pinned. This may be fewer than the number
1435 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1436 * were pinned, returns -errno. Each page returned must be released
1437 * with a put_page() call when it is finished with. vmas will only
1438 * remain valid while mmap_sem is held.
1439 *
1440 * Must be called with mmap_sem held for read or write.
1441 *
1442 * __get_user_pages walks a process's page tables and takes a reference to
1443 * each struct page that each user address corresponds to at a given
1444 * instant. That is, it takes the page that would be accessed if a user
1445 * thread accesses the given user virtual address at that instant.
1446 *
1447 * This does not guarantee that the page exists in the user mappings when
1448 * __get_user_pages returns, and there may even be a completely different
1449 * page there in some cases (eg. if mmapped pagecache has been invalidated
1450 * and subsequently re faulted). However it does guarantee that the page
1451 * won't be freed completely. And mostly callers simply care that the page
1452 * contains data that was valid *at some point in time*. Typically, an IO
1453 * or similar operation cannot guarantee anything stronger anyway because
1454 * locks can't be held over the syscall boundary.
1455 *
1456 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1457 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1458 * appropriate) must be called after the page is finished with, and
1459 * before put_page is called.
1460 *
1461 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1462 * or mmap_sem contention, and if waiting is needed to pin all pages,
1463 * *@nonblocking will be set to 0.
1464 *
1465 * In most cases, get_user_pages or get_user_pages_fast should be used
1466 * instead of __get_user_pages. __get_user_pages should be used only if
1467 * you need some special @gup_flags.
1468 */
Nick Pigginb291f002008-10-18 20:26:44 -07001469int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
Hugh Dickins58fa8792009-09-21 17:03:31 -07001470 unsigned long start, int nr_pages, unsigned int gup_flags,
Michel Lespinasse53a77062011-01-13 15:46:14 -08001471 struct page **pages, struct vm_area_struct **vmas,
1472 int *nonblocking)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473{
1474 int i;
Hugh Dickins58fa8792009-09-21 17:03:31 -07001475 unsigned long vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476
Peter Zijlstra9d737772009-06-25 11:58:55 +02001477 if (nr_pages <= 0)
Jonathan Corbet900cf082008-02-11 16:17:33 -07001478 return 0;
Hugh Dickins58fa8792009-09-21 17:03:31 -07001479
1480 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1481
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482 /*
1483 * Require read or write permissions.
Hugh Dickins58fa8792009-09-21 17:03:31 -07001484 * If FOLL_FORCE is set, we only require the "MAY" flags.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485 */
Hugh Dickins58fa8792009-09-21 17:03:31 -07001486 vm_flags = (gup_flags & FOLL_WRITE) ?
1487 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
1488 vm_flags &= (gup_flags & FOLL_FORCE) ?
1489 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 i = 0;
1491
1492 do {
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001493 struct vm_area_struct *vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494
1495 vma = find_extend_vma(mm, start);
Stephen Wilsone7f22e22011-03-13 15:49:18 -04001496 if (!vma && in_gate_area(mm, start)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497 unsigned long pg = start & PAGE_MASK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498 pgd_t *pgd;
1499 pud_t *pud;
1500 pmd_t *pmd;
1501 pte_t *pte;
Nick Pigginb291f002008-10-18 20:26:44 -07001502
1503 /* user gate pages are read-only */
Hugh Dickins58fa8792009-09-21 17:03:31 -07001504 if (gup_flags & FOLL_WRITE)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 return i ? : -EFAULT;
1506 if (pg > TASK_SIZE)
1507 pgd = pgd_offset_k(pg);
1508 else
1509 pgd = pgd_offset_gate(mm, pg);
1510 BUG_ON(pgd_none(*pgd));
1511 pud = pud_offset(pgd, pg);
1512 BUG_ON(pud_none(*pud));
1513 pmd = pmd_offset(pud, pg);
Hugh Dickins690dbe12005-08-01 21:11:42 -07001514 if (pmd_none(*pmd))
1515 return i ? : -EFAULT;
Andrea Arcangelif66055a2011-01-13 15:46:54 -08001516 VM_BUG_ON(pmd_trans_huge(*pmd));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517 pte = pte_offset_map(pmd, pg);
Hugh Dickins690dbe12005-08-01 21:11:42 -07001518 if (pte_none(*pte)) {
1519 pte_unmap(pte);
1520 return i ? : -EFAULT;
1521 }
Linus Torvalds95042f92011-04-12 14:15:51 -07001522 vma = get_gate_vma(mm);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523 if (pages) {
Hugh Dickinsde512572010-07-30 10:58:26 -07001524 struct page *page;
1525
Linus Torvalds95042f92011-04-12 14:15:51 -07001526 page = vm_normal_page(vma, start, *pte);
Hugh Dickinsde512572010-07-30 10:58:26 -07001527 if (!page) {
1528 if (!(gup_flags & FOLL_DUMP) &&
1529 is_zero_pfn(pte_pfn(*pte)))
1530 page = pte_page(*pte);
1531 else {
1532 pte_unmap(pte);
1533 return i ? : -EFAULT;
1534 }
1535 }
Linus Torvalds6aab3412005-11-28 14:34:23 -08001536 pages[i] = page;
Hugh Dickinsde512572010-07-30 10:58:26 -07001537 get_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538 }
1539 pte_unmap(pte);
Linus Torvalds95042f92011-04-12 14:15:51 -07001540 goto next_page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541 }
1542
Nick Pigginb291f002008-10-18 20:26:44 -07001543 if (!vma ||
1544 (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
Hugh Dickins1c3aff12009-09-21 17:03:24 -07001545 !(vm_flags & vma->vm_flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 return i ? : -EFAULT;
1547
Hugh Dickins2a15efc2009-09-21 17:03:27 -07001548 if (is_vm_hugetlb_page(vma)) {
1549 i = follow_hugetlb_page(mm, vma, pages, vmas,
Hugh Dickins58fa8792009-09-21 17:03:31 -07001550 &start, &nr_pages, i, gup_flags);
Hugh Dickins2a15efc2009-09-21 17:03:27 -07001551 continue;
1552 }
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001553
Linus Torvalds95042f92011-04-12 14:15:51 -07001554 /*
1555 * If we don't actually want the page itself,
1556 * and it's the stack guard page, just skip it.
1557 */
1558 if (!pages && stack_guard_page(vma, start))
1559 goto next_page;
1560
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561 do {
Hugh Dickins08ef4722005-06-21 17:15:10 -07001562 struct page *page;
Hugh Dickins58fa8792009-09-21 17:03:31 -07001563 unsigned int foll_flags = gup_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564
Ethan Solomita462e00c2007-07-15 23:38:16 -07001565 /*
Ying Han47792802009-01-06 14:40:18 -08001566 * If we have a pending SIGKILL, don't keep faulting
Hugh Dickins1c3aff12009-09-21 17:03:24 -07001567 * pages and potentially allocating memory.
Ethan Solomita462e00c2007-07-15 23:38:16 -07001568 */
Hugh Dickins1c3aff12009-09-21 17:03:24 -07001569 if (unlikely(fatal_signal_pending(current)))
Ying Han47792802009-01-06 14:40:18 -08001570 return i ? i : -ERESTARTSYS;
Ethan Solomita462e00c2007-07-15 23:38:16 -07001571
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001572 cond_resched();
Linus Torvalds6aab3412005-11-28 14:34:23 -08001573 while (!(page = follow_page(vma, start, foll_flags))) {
Linus Torvaldsa68d2eb2005-08-03 10:07:09 -07001574 int ret;
Michel Lespinasse53a77062011-01-13 15:46:14 -08001575 unsigned int fault_flags = 0;
1576
1577 if (foll_flags & FOLL_WRITE)
1578 fault_flags |= FAULT_FLAG_WRITE;
1579 if (nonblocking)
1580 fault_flags |= FAULT_FLAG_ALLOW_RETRY;
Gleb Natapov318b2752011-03-22 16:30:51 -07001581 if (foll_flags & FOLL_NOWAIT)
1582 fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
Linus Torvaldsd06063c2009-04-10 09:01:23 -07001583
Hugh Dickinsd26ed652009-06-23 13:52:49 +01001584 ret = handle_mm_fault(mm, vma, start,
Michel Lespinasse53a77062011-01-13 15:46:14 -08001585 fault_flags);
Hugh Dickinsd26ed652009-06-23 13:52:49 +01001586
Nick Piggin83c54072007-07-19 01:47:05 -07001587 if (ret & VM_FAULT_ERROR) {
1588 if (ret & VM_FAULT_OOM)
1589 return i ? i : -ENOMEM;
Huang Ying69ebb832011-01-30 11:15:48 +08001590 if (ret & (VM_FAULT_HWPOISON |
1591 VM_FAULT_HWPOISON_LARGE)) {
1592 if (i)
1593 return i;
1594 else if (gup_flags & FOLL_HWPOISON)
1595 return -EHWPOISON;
1596 else
1597 return -EFAULT;
1598 }
1599 if (ret & VM_FAULT_SIGBUS)
Nick Piggin83c54072007-07-19 01:47:05 -07001600 return i ? i : -EFAULT;
1601 BUG();
1602 }
Stephen Wilsone7f22e22011-03-13 15:49:18 -04001603
1604 if (tsk) {
1605 if (ret & VM_FAULT_MAJOR)
1606 tsk->maj_flt++;
1607 else
1608 tsk->min_flt++;
1609 }
Nick Piggin83c54072007-07-19 01:47:05 -07001610
Michel Lespinasse53a77062011-01-13 15:46:14 -08001611 if (ret & VM_FAULT_RETRY) {
Gleb Natapov318b2752011-03-22 16:30:51 -07001612 if (nonblocking)
1613 *nonblocking = 0;
Michel Lespinasse53a77062011-01-13 15:46:14 -08001614 return i;
1615 }
1616
Linus Torvaldsa68d2eb2005-08-03 10:07:09 -07001617 /*
Nick Piggin83c54072007-07-19 01:47:05 -07001618 * The VM_FAULT_WRITE bit tells us that
1619 * do_wp_page has broken COW when necessary,
1620 * even if maybe_mkwrite decided not to set
1621 * pte_write. We can thus safely do subsequent
Hugh Dickins878b63a2009-01-06 14:39:32 -08001622 * page lookups as if they were reads. But only
1623 * do so when looping for pte_write is futile:
1624 * in some cases userspace may also be wanting
1625 * to write to the gotten user page, which a
1626 * read fault here might prevent (a readonly
1627 * page might get reCOWed by userspace write).
Linus Torvaldsa68d2eb2005-08-03 10:07:09 -07001628 */
Hugh Dickins878b63a2009-01-06 14:39:32 -08001629 if ((ret & VM_FAULT_WRITE) &&
1630 !(vma->vm_flags & VM_WRITE))
Hugh Dickinsdeceb6c2005-10-29 18:16:33 -07001631 foll_flags &= ~FOLL_WRITE;
Nick Piggin83c54072007-07-19 01:47:05 -07001632
Benjamin Herrenschmidt7f7bbbe2006-10-06 00:43:53 -07001633 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634 }
Linus Torvalds89f5b7d2008-06-20 11:18:25 -07001635 if (IS_ERR(page))
1636 return i ? i : PTR_ERR(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 if (pages) {
Hugh Dickins08ef4722005-06-21 17:15:10 -07001638 pages[i] = page;
James Bottomley03beb072006-03-26 01:36:57 -08001639
Russell Kinga6f36be2006-12-30 22:24:19 +00001640 flush_anon_page(vma, page, start);
Hugh Dickins08ef4722005-06-21 17:15:10 -07001641 flush_dcache_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 }
Linus Torvalds95042f92011-04-12 14:15:51 -07001643next_page:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001644 if (vmas)
1645 vmas[i] = vma;
1646 i++;
1647 start += PAGE_SIZE;
Peter Zijlstra9d737772009-06-25 11:58:55 +02001648 nr_pages--;
1649 } while (nr_pages && start < vma->vm_end);
1650 } while (nr_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651 return i;
1652}
Huang Ying0014bd92011-01-30 11:15:47 +08001653EXPORT_SYMBOL(__get_user_pages);
Nick Pigginb291f002008-10-18 20:26:44 -07001654
Nick Piggind2bf6be2009-06-16 15:31:39 -07001655/**
1656 * get_user_pages() - pin user pages in memory
Stephen Wilsone7f22e22011-03-13 15:49:18 -04001657 * @tsk: the task_struct to use for page fault accounting, or
1658 * NULL if faults are not to be recorded.
Nick Piggind2bf6be2009-06-16 15:31:39 -07001659 * @mm: mm_struct of target mm
1660 * @start: starting user address
Peter Zijlstra9d737772009-06-25 11:58:55 +02001661 * @nr_pages: number of pages from start to pin
Nick Piggind2bf6be2009-06-16 15:31:39 -07001662 * @write: whether pages will be written to by the caller
1663 * @force: whether to force write access even if user mapping is
1664 * readonly. This will result in the page being COWed even
1665 * in MAP_SHARED mappings. You do not want this.
1666 * @pages: array that receives pointers to the pages pinned.
1667 * Should be at least nr_pages long. Or NULL, if caller
1668 * only intends to ensure the pages are faulted in.
1669 * @vmas: array of pointers to vmas corresponding to each page.
1670 * Or NULL if the caller does not require them.
1671 *
1672 * Returns number of pages pinned. This may be fewer than the number
Peter Zijlstra9d737772009-06-25 11:58:55 +02001673 * requested. If nr_pages is 0 or negative, returns 0. If no pages
Nick Piggind2bf6be2009-06-16 15:31:39 -07001674 * were pinned, returns -errno. Each page returned must be released
1675 * with a put_page() call when it is finished with. vmas will only
1676 * remain valid while mmap_sem is held.
1677 *
1678 * Must be called with mmap_sem held for read or write.
1679 *
1680 * get_user_pages walks a process's page tables and takes a reference to
1681 * each struct page that each user address corresponds to at a given
1682 * instant. That is, it takes the page that would be accessed if a user
1683 * thread accesses the given user virtual address at that instant.
1684 *
1685 * This does not guarantee that the page exists in the user mappings when
1686 * get_user_pages returns, and there may even be a completely different
1687 * page there in some cases (eg. if mmapped pagecache has been invalidated
1688 * and subsequently re faulted). However it does guarantee that the page
1689 * won't be freed completely. And mostly callers simply care that the page
1690 * contains data that was valid *at some point in time*. Typically, an IO
1691 * or similar operation cannot guarantee anything stronger anyway because
1692 * locks can't be held over the syscall boundary.
1693 *
1694 * If write=0, the page must not be written to. If the page is written to,
1695 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
1696 * after the page is finished with, and before put_page is called.
1697 *
1698 * get_user_pages is typically used for fewer-copy IO operations, to get a
1699 * handle on the memory by some means other than accesses via the user virtual
1700 * addresses. The pages may be submitted for DMA to devices or accessed via
1701 * their kernel linear mapping (via the kmap APIs). Care should be taken to
1702 * use the correct cache flushing APIs.
1703 *
1704 * See also get_user_pages_fast, for performance critical applications.
1705 */
Nick Pigginb291f002008-10-18 20:26:44 -07001706int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
Peter Zijlstra9d737772009-06-25 11:58:55 +02001707 unsigned long start, int nr_pages, int write, int force,
Nick Pigginb291f002008-10-18 20:26:44 -07001708 struct page **pages, struct vm_area_struct **vmas)
1709{
Hugh Dickins58fa8792009-09-21 17:03:31 -07001710 int flags = FOLL_TOUCH;
Nick Pigginb291f002008-10-18 20:26:44 -07001711
Hugh Dickins58fa8792009-09-21 17:03:31 -07001712 if (pages)
1713 flags |= FOLL_GET;
Nick Pigginb291f002008-10-18 20:26:44 -07001714 if (write)
Hugh Dickins58fa8792009-09-21 17:03:31 -07001715 flags |= FOLL_WRITE;
Nick Pigginb291f002008-10-18 20:26:44 -07001716 if (force)
Hugh Dickins58fa8792009-09-21 17:03:31 -07001717 flags |= FOLL_FORCE;
Nick Pigginb291f002008-10-18 20:26:44 -07001718
Michel Lespinasse53a77062011-01-13 15:46:14 -08001719 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
1720 NULL);
Nick Pigginb291f002008-10-18 20:26:44 -07001721}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722EXPORT_SYMBOL(get_user_pages);
1723
Hugh Dickinsf3e8fcc2009-09-21 17:03:25 -07001724/**
1725 * get_dump_page() - pin user page in memory while writing it to core dump
1726 * @addr: user address
1727 *
1728 * Returns struct page pointer of user page pinned for dump,
1729 * to be freed afterwards by page_cache_release() or put_page().
1730 *
1731 * Returns NULL on any kind of failure - a hole must then be inserted into
1732 * the corefile, to preserve alignment with its headers; and also returns
1733 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
1734 * allowing a hole to be left in the corefile to save diskspace.
1735 *
1736 * Called without mmap_sem, but after all other threads have been killed.
1737 */
1738#ifdef CONFIG_ELF_CORE
1739struct page *get_dump_page(unsigned long addr)
1740{
1741 struct vm_area_struct *vma;
1742 struct page *page;
1743
1744 if (__get_user_pages(current, current->mm, addr, 1,
Michel Lespinasse53a77062011-01-13 15:46:14 -08001745 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
1746 NULL) < 1)
Hugh Dickinsf3e8fcc2009-09-21 17:03:25 -07001747 return NULL;
Hugh Dickinsf3e8fcc2009-09-21 17:03:25 -07001748 flush_cache_page(vma, addr, page_to_pfn(page));
1749 return page;
1750}
1751#endif /* CONFIG_ELF_CORE */
1752
Namhyung Kim25ca1d62010-10-26 14:21:59 -07001753pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
Harvey Harrison920c7a52008-02-04 22:29:26 -08001754 spinlock_t **ptl)
Linus Torvaldsc9cfcdd2005-11-29 14:03:14 -08001755{
1756 pgd_t * pgd = pgd_offset(mm, addr);
1757 pud_t * pud = pud_alloc(mm, pgd, addr);
1758 if (pud) {
Trond Myklebust49c91fb2005-11-29 19:27:22 -05001759 pmd_t * pmd = pmd_alloc(mm, pud, addr);
Andrea Arcangelif66055a2011-01-13 15:46:54 -08001760 if (pmd) {
1761 VM_BUG_ON(pmd_trans_huge(*pmd));
Linus Torvaldsc9cfcdd2005-11-29 14:03:14 -08001762 return pte_alloc_map_lock(mm, pmd, addr, ptl);
Andrea Arcangelif66055a2011-01-13 15:46:54 -08001763 }
Linus Torvaldsc9cfcdd2005-11-29 14:03:14 -08001764 }
1765 return NULL;
1766}
1767
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768/*
Linus Torvalds238f58d2005-11-29 13:01:56 -08001769 * This is the old fallback for page remapping.
1770 *
1771 * For historical reasons, it only allows reserved pages. Only
1772 * old drivers should use this, and they needed to mark their
1773 * pages reserved for the old functions anyway.
1774 */
Nick Piggin423bad62008-04-28 02:13:01 -07001775static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1776 struct page *page, pgprot_t prot)
Linus Torvalds238f58d2005-11-29 13:01:56 -08001777{
Nick Piggin423bad62008-04-28 02:13:01 -07001778 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds238f58d2005-11-29 13:01:56 -08001779 int retval;
Linus Torvaldsc9cfcdd2005-11-29 14:03:14 -08001780 pte_t *pte;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -08001781 spinlock_t *ptl;
1782
Linus Torvalds238f58d2005-11-29 13:01:56 -08001783 retval = -EINVAL;
Linus Torvaldsa145dd42005-11-30 09:35:19 -08001784 if (PageAnon(page))
KAMEZAWA Hiroyuki5b4e6552008-10-18 20:28:10 -07001785 goto out;
Linus Torvalds238f58d2005-11-29 13:01:56 -08001786 retval = -ENOMEM;
1787 flush_dcache_page(page);
Linus Torvaldsc9cfcdd2005-11-29 14:03:14 -08001788 pte = get_locked_pte(mm, addr, &ptl);
Linus Torvalds238f58d2005-11-29 13:01:56 -08001789 if (!pte)
KAMEZAWA Hiroyuki5b4e6552008-10-18 20:28:10 -07001790 goto out;
Linus Torvalds238f58d2005-11-29 13:01:56 -08001791 retval = -EBUSY;
1792 if (!pte_none(*pte))
1793 goto out_unlock;
1794
1795 /* Ok, finally just insert the thing.. */
1796 get_page(page);
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -08001797 inc_mm_counter_fast(mm, MM_FILEPAGES);
Linus Torvalds238f58d2005-11-29 13:01:56 -08001798 page_add_file_rmap(page);
1799 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1800
1801 retval = 0;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -08001802 pte_unmap_unlock(pte, ptl);
1803 return retval;
Linus Torvalds238f58d2005-11-29 13:01:56 -08001804out_unlock:
1805 pte_unmap_unlock(pte, ptl);
1806out:
1807 return retval;
1808}
1809
Rolf Eike Beerbfa5bf62006-09-25 23:31:22 -07001810/**
1811 * vm_insert_page - insert single page into user vma
1812 * @vma: user vma to map to
1813 * @addr: target user address of this page
1814 * @page: source kernel page
1815 *
Linus Torvaldsa145dd42005-11-30 09:35:19 -08001816 * This allows drivers to insert individual pages they've allocated
1817 * into a user vma.
1818 *
1819 * The page has to be a nice clean _individual_ kernel allocation.
1820 * If you allocate a compound page, you need to have marked it as
1821 * such (__GFP_COMP), or manually just split the page up yourself
Nick Piggin8dfcc9b2006-03-22 00:08:05 -08001822 * (see split_page()).
Linus Torvaldsa145dd42005-11-30 09:35:19 -08001823 *
1824 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1825 * took an arbitrary page protection parameter. This doesn't allow
1826 * that. Your vma protection will have to be set up correctly, which
1827 * means that if you want a shared writable mapping, you'd better
1828 * ask for a shared writable mapping!
1829 *
1830 * The page does not need to be reserved.
1831 */
Nick Piggin423bad62008-04-28 02:13:01 -07001832int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1833 struct page *page)
Linus Torvaldsa145dd42005-11-30 09:35:19 -08001834{
1835 if (addr < vma->vm_start || addr >= vma->vm_end)
1836 return -EFAULT;
1837 if (!page_count(page))
1838 return -EINVAL;
Linus Torvalds4d7672b2005-12-16 10:21:23 -08001839 vma->vm_flags |= VM_INSERTPAGE;
Nick Piggin423bad62008-04-28 02:13:01 -07001840 return insert_page(vma, addr, page, vma->vm_page_prot);
Linus Torvaldsa145dd42005-11-30 09:35:19 -08001841}
Linus Torvaldse3c33742005-12-03 20:48:11 -08001842EXPORT_SYMBOL(vm_insert_page);
Linus Torvaldsa145dd42005-11-30 09:35:19 -08001843
Nick Piggin423bad62008-04-28 02:13:01 -07001844static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1845 unsigned long pfn, pgprot_t prot)
1846{
1847 struct mm_struct *mm = vma->vm_mm;
1848 int retval;
1849 pte_t *pte, entry;
1850 spinlock_t *ptl;
1851
1852 retval = -ENOMEM;
1853 pte = get_locked_pte(mm, addr, &ptl);
1854 if (!pte)
1855 goto out;
1856 retval = -EBUSY;
1857 if (!pte_none(*pte))
1858 goto out_unlock;
1859
1860 /* Ok, finally just insert the thing.. */
1861 entry = pte_mkspecial(pfn_pte(pfn, prot));
1862 set_pte_at(mm, addr, pte, entry);
Russell King4b3073e2009-12-18 16:40:18 +00001863 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
Nick Piggin423bad62008-04-28 02:13:01 -07001864
1865 retval = 0;
1866out_unlock:
1867 pte_unmap_unlock(pte, ptl);
1868out:
1869 return retval;
1870}
1871
Nick Piggine0dc0d82007-02-12 00:51:36 -08001872/**
1873 * vm_insert_pfn - insert single pfn into user vma
1874 * @vma: user vma to map to
1875 * @addr: target user address of this page
1876 * @pfn: source kernel pfn
1877 *
1878 * Similar to vm_inert_page, this allows drivers to insert individual pages
1879 * they've allocated into a user vma. Same comments apply.
1880 *
1881 * This function should only be called from a vm_ops->fault handler, and
1882 * in that case the handler should return NULL.
Nick Piggin0d71d10a2008-07-23 21:27:05 -07001883 *
1884 * vma cannot be a COW mapping.
1885 *
1886 * As this is called only for pages that do not currently exist, we
1887 * do not need to flush old virtual caches or the TLB.
Nick Piggine0dc0d82007-02-12 00:51:36 -08001888 */
1889int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
Nick Piggin423bad62008-04-28 02:13:01 -07001890 unsigned long pfn)
Nick Piggine0dc0d82007-02-12 00:51:36 -08001891{
venkatesh.pallipadi@intel.com2ab64032008-12-18 11:41:29 -08001892 int ret;
venkatesh.pallipadi@intel.come4b866e2009-01-09 16:13:11 -08001893 pgprot_t pgprot = vma->vm_page_prot;
Nick Piggin7e675132008-04-28 02:13:00 -07001894 /*
1895 * Technically, architectures with pte_special can avoid all these
1896 * restrictions (same for remap_pfn_range). However we would like
1897 * consistency in testing and feature parity among all, so we should
1898 * try to keep these invariants in place for everybody.
1899 */
Jared Hulbertb379d792008-04-28 02:12:58 -07001900 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1901 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1902 (VM_PFNMAP|VM_MIXEDMAP));
1903 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1904 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
Nick Piggine0dc0d82007-02-12 00:51:36 -08001905
Nick Piggin423bad62008-04-28 02:13:01 -07001906 if (addr < vma->vm_start || addr >= vma->vm_end)
1907 return -EFAULT;
venkatesh.pallipadi@intel.come4b866e2009-01-09 16:13:11 -08001908 if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
venkatesh.pallipadi@intel.com2ab64032008-12-18 11:41:29 -08001909 return -EINVAL;
1910
venkatesh.pallipadi@intel.come4b866e2009-01-09 16:13:11 -08001911 ret = insert_pfn(vma, addr, pfn, pgprot);
venkatesh.pallipadi@intel.com2ab64032008-12-18 11:41:29 -08001912
1913 if (ret)
1914 untrack_pfn_vma(vma, pfn, PAGE_SIZE);
1915
1916 return ret;
Nick Piggine0dc0d82007-02-12 00:51:36 -08001917}
1918EXPORT_SYMBOL(vm_insert_pfn);
1919
Nick Piggin423bad62008-04-28 02:13:01 -07001920int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1921 unsigned long pfn)
1922{
1923 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1924
1925 if (addr < vma->vm_start || addr >= vma->vm_end)
1926 return -EFAULT;
1927
1928 /*
1929 * If we don't have pte special, then we have to use the pfn_valid()
1930 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1931 * refcount the page if pfn_valid is true (hence insert_page rather
Hugh Dickins62eede62009-09-21 17:03:34 -07001932 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1933 * without pte special, it would there be refcounted as a normal page.
Nick Piggin423bad62008-04-28 02:13:01 -07001934 */
1935 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
1936 struct page *page;
1937
1938 page = pfn_to_page(pfn);
1939 return insert_page(vma, addr, page, vma->vm_page_prot);
1940 }
1941 return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
1942}
1943EXPORT_SYMBOL(vm_insert_mixed);
1944
Linus Torvaldsa145dd42005-11-30 09:35:19 -08001945/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946 * maps a range of physical memory into the requested pages. the old
1947 * mappings are removed. any references to nonexistent pages results
1948 * in null mappings (currently treated as "copy-on-access")
1949 */
1950static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1951 unsigned long addr, unsigned long end,
1952 unsigned long pfn, pgprot_t prot)
1953{
1954 pte_t *pte;
Hugh Dickinsc74df322005-10-29 18:16:23 -07001955 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001956
Hugh Dickinsc74df322005-10-29 18:16:23 -07001957 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001958 if (!pte)
1959 return -ENOMEM;
Zachary Amsden6606c3e2006-09-30 23:29:33 -07001960 arch_enter_lazy_mmu_mode();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001961 do {
1962 BUG_ON(!pte_none(*pte));
Nick Piggin7e675132008-04-28 02:13:00 -07001963 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001964 pfn++;
1965 } while (pte++, addr += PAGE_SIZE, addr != end);
Zachary Amsden6606c3e2006-09-30 23:29:33 -07001966 arch_leave_lazy_mmu_mode();
Hugh Dickinsc74df322005-10-29 18:16:23 -07001967 pte_unmap_unlock(pte - 1, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001968 return 0;
1969}
1970
1971static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1972 unsigned long addr, unsigned long end,
1973 unsigned long pfn, pgprot_t prot)
1974{
1975 pmd_t *pmd;
1976 unsigned long next;
1977
1978 pfn -= addr >> PAGE_SHIFT;
1979 pmd = pmd_alloc(mm, pud, addr);
1980 if (!pmd)
1981 return -ENOMEM;
Andrea Arcangelif66055a2011-01-13 15:46:54 -08001982 VM_BUG_ON(pmd_trans_huge(*pmd));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001983 do {
1984 next = pmd_addr_end(addr, end);
1985 if (remap_pte_range(mm, pmd, addr, next,
1986 pfn + (addr >> PAGE_SHIFT), prot))
1987 return -ENOMEM;
1988 } while (pmd++, addr = next, addr != end);
1989 return 0;
1990}
1991
1992static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
1993 unsigned long addr, unsigned long end,
1994 unsigned long pfn, pgprot_t prot)
1995{
1996 pud_t *pud;
1997 unsigned long next;
1998
1999 pfn -= addr >> PAGE_SHIFT;
2000 pud = pud_alloc(mm, pgd, addr);
2001 if (!pud)
2002 return -ENOMEM;
2003 do {
2004 next = pud_addr_end(addr, end);
2005 if (remap_pmd_range(mm, pud, addr, next,
2006 pfn + (addr >> PAGE_SHIFT), prot))
2007 return -ENOMEM;
2008 } while (pud++, addr = next, addr != end);
2009 return 0;
2010}
2011
Rolf Eike Beerbfa5bf62006-09-25 23:31:22 -07002012/**
2013 * remap_pfn_range - remap kernel memory to userspace
2014 * @vma: user vma to map to
2015 * @addr: target user address to start at
2016 * @pfn: physical address of kernel memory
2017 * @size: size of map area
2018 * @prot: page protection flags for this mapping
2019 *
2020 * Note: this is only safe if the mm semaphore is held when called.
2021 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002022int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2023 unsigned long pfn, unsigned long size, pgprot_t prot)
2024{
2025 pgd_t *pgd;
2026 unsigned long next;
Hugh Dickins2d15cab2005-06-25 14:54:33 -07002027 unsigned long end = addr + PAGE_ALIGN(size);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002028 struct mm_struct *mm = vma->vm_mm;
2029 int err;
2030
2031 /*
2032 * Physically remapped pages are special. Tell the
2033 * rest of the world about it:
2034 * VM_IO tells people not to look at these pages
2035 * (accesses can have side effects).
Hugh Dickins0b14c172005-11-21 21:32:15 -08002036 * VM_RESERVED is specified all over the place, because
2037 * in 2.4 it kept swapout's vma scan off this vma; but
2038 * in 2.6 the LRU scan won't even find its pages, so this
2039 * flag means no more than count its pages in reserved_vm,
2040 * and omit it from core dump, even when VM_IO turned off.
Linus Torvalds6aab3412005-11-28 14:34:23 -08002041 * VM_PFNMAP tells the core MM that the base pages are just
2042 * raw PFN mappings, and do not have a "struct page" associated
2043 * with them.
Linus Torvaldsfb155c12005-12-11 19:46:02 -08002044 *
2045 * There's a horrible special case to handle copy-on-write
2046 * behaviour that some programs depend on. We mark the "original"
2047 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
Linus Torvalds1da177e2005-04-16 15:20:36 -07002048 */
Pallipadi, Venkatesh4bb9c5c2009-03-12 17:45:27 -07002049 if (addr == vma->vm_start && end == vma->vm_end) {
Linus Torvaldsfb155c12005-12-11 19:46:02 -08002050 vma->vm_pgoff = pfn;
Pallipadi, Venkatesh895791d2009-03-13 16:35:44 -07002051 vma->vm_flags |= VM_PFN_AT_MMAP;
Pallipadi, Venkatesh4bb9c5c2009-03-12 17:45:27 -07002052 } else if (is_cow_mapping(vma->vm_flags))
venkatesh.pallipadi@intel.com3c8bb732008-12-18 11:41:27 -08002053 return -EINVAL;
Linus Torvaldsfb155c12005-12-11 19:46:02 -08002054
Linus Torvalds6aab3412005-11-28 14:34:23 -08002055 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002056
venkatesh.pallipadi@intel.come4b866e2009-01-09 16:13:11 -08002057 err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
venkatesh.pallipadi@intel.coma3670612009-01-09 16:13:09 -08002058 if (err) {
2059 /*
2060 * To indicate that track_pfn related cleanup is not
2061 * needed from higher level routine calling unmap_vmas
2062 */
2063 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
Pallipadi, Venkatesh895791d2009-03-13 16:35:44 -07002064 vma->vm_flags &= ~VM_PFN_AT_MMAP;
venkatesh.pallipadi@intel.com2ab64032008-12-18 11:41:29 -08002065 return -EINVAL;
venkatesh.pallipadi@intel.coma3670612009-01-09 16:13:09 -08002066 }
venkatesh.pallipadi@intel.com2ab64032008-12-18 11:41:29 -08002067
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068 BUG_ON(addr >= end);
2069 pfn -= addr >> PAGE_SHIFT;
2070 pgd = pgd_offset(mm, addr);
2071 flush_cache_range(vma, addr, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002072 do {
2073 next = pgd_addr_end(addr, end);
2074 err = remap_pud_range(mm, pgd, addr, next,
2075 pfn + (addr >> PAGE_SHIFT), prot);
2076 if (err)
2077 break;
2078 } while (pgd++, addr = next, addr != end);
venkatesh.pallipadi@intel.com2ab64032008-12-18 11:41:29 -08002079
2080 if (err)
2081 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));
2082
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083 return err;
2084}
2085EXPORT_SYMBOL(remap_pfn_range);
2086
Jeremy Fitzhardingeaee16b32007-05-06 14:48:54 -07002087static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2088 unsigned long addr, unsigned long end,
2089 pte_fn_t fn, void *data)
2090{
2091 pte_t *pte;
2092 int err;
Martin Schwidefsky2f569af2008-02-08 04:22:04 -08002093 pgtable_t token;
Borislav Petkov94909912007-05-06 14:49:17 -07002094 spinlock_t *uninitialized_var(ptl);
Jeremy Fitzhardingeaee16b32007-05-06 14:48:54 -07002095
2096 pte = (mm == &init_mm) ?
2097 pte_alloc_kernel(pmd, addr) :
2098 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2099 if (!pte)
2100 return -ENOMEM;
2101
2102 BUG_ON(pmd_huge(*pmd));
2103
Jeremy Fitzhardinge38e0edb2009-01-06 14:39:21 -08002104 arch_enter_lazy_mmu_mode();
2105
Martin Schwidefsky2f569af2008-02-08 04:22:04 -08002106 token = pmd_pgtable(*pmd);
Jeremy Fitzhardingeaee16b32007-05-06 14:48:54 -07002107
2108 do {
Daisuke Nishimurac36987e2009-10-26 16:50:23 -07002109 err = fn(pte++, token, addr, data);
Jeremy Fitzhardingeaee16b32007-05-06 14:48:54 -07002110 if (err)
2111 break;
Daisuke Nishimurac36987e2009-10-26 16:50:23 -07002112 } while (addr += PAGE_SIZE, addr != end);
Jeremy Fitzhardingeaee16b32007-05-06 14:48:54 -07002113
Jeremy Fitzhardinge38e0edb2009-01-06 14:39:21 -08002114 arch_leave_lazy_mmu_mode();
2115
Jeremy Fitzhardingeaee16b32007-05-06 14:48:54 -07002116 if (mm != &init_mm)
2117 pte_unmap_unlock(pte-1, ptl);
2118 return err;
2119}
2120
2121static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2122 unsigned long addr, unsigned long end,
2123 pte_fn_t fn, void *data)
2124{
2125 pmd_t *pmd;
2126 unsigned long next;
2127 int err;
2128
Andi Kleenceb86872008-07-23 21:27:50 -07002129 BUG_ON(pud_huge(*pud));
2130
Jeremy Fitzhardingeaee16b32007-05-06 14:48:54 -07002131 pmd = pmd_alloc(mm, pud, addr);
2132 if (!pmd)
2133 return -ENOMEM;
2134 do {
2135 next = pmd_addr_end(addr, end);
2136 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2137 if (err)
2138 break;
2139 } while (pmd++, addr = next, addr != end);
2140 return err;
2141}
2142
2143static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2144 unsigned long addr, unsigned long end,
2145 pte_fn_t fn, void *data)
2146{
2147 pud_t *pud;
2148 unsigned long next;
2149 int err;
2150
2151 pud = pud_alloc(mm, pgd, addr);
2152 if (!pud)
2153 return -ENOMEM;
2154 do {
2155 next = pud_addr_end(addr, end);
2156 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2157 if (err)
2158 break;
2159 } while (pud++, addr = next, addr != end);
2160 return err;
2161}
2162
2163/*
2164 * Scan a region of virtual memory, filling in page tables as necessary
2165 * and calling a provided function on each leaf page table.
2166 */
2167int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2168 unsigned long size, pte_fn_t fn, void *data)
2169{
2170 pgd_t *pgd;
2171 unsigned long next;
Jeremy Fitzhardinge57250a52010-08-09 17:19:52 -07002172 unsigned long end = addr + size;
Jeremy Fitzhardingeaee16b32007-05-06 14:48:54 -07002173 int err;
2174
2175 BUG_ON(addr >= end);
2176 pgd = pgd_offset(mm, addr);
2177 do {
2178 next = pgd_addr_end(addr, end);
2179 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2180 if (err)
2181 break;
2182 } while (pgd++, addr = next, addr != end);
Jeremy Fitzhardinge57250a52010-08-09 17:19:52 -07002183
Jeremy Fitzhardingeaee16b32007-05-06 14:48:54 -07002184 return err;
2185}
2186EXPORT_SYMBOL_GPL(apply_to_page_range);
2187
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188/*
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002189 * handle_pte_fault chooses page fault handler according to an entry
2190 * which was read non-atomically. Before making any commitment, on
2191 * those architectures or configurations (e.g. i386 with PAE) which
Ryota Ozakia335b2e2011-02-10 13:56:28 +09002192 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002193 * must check under lock before unmapping the pte and proceeding
2194 * (but do_wp_page is only called after already making such a check;
Ryota Ozakia335b2e2011-02-10 13:56:28 +09002195 * and do_anonymous_page can safely check later on).
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002196 */
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07002197static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002198 pte_t *page_table, pte_t orig_pte)
2199{
2200 int same = 1;
2201#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2202 if (sizeof(pte_t) > sizeof(unsigned long)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07002203 spinlock_t *ptl = pte_lockptr(mm, pmd);
2204 spin_lock(ptl);
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002205 same = pte_same(*page_table, orig_pte);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07002206 spin_unlock(ptl);
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002207 }
2208#endif
2209 pte_unmap(page_table);
2210 return same;
2211}
2212
Atsushi Nemoto9de455b2006-12-12 17:14:55 +00002213static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
Linus Torvalds6aab3412005-11-28 14:34:23 -08002214{
2215 /*
2216 * If the source page was a PFN mapping, we don't have
2217 * a "struct page" for it. We do a best-effort copy by
2218 * just copying from the original user address. If that
2219 * fails, we just zero-fill it. Live with it.
2220 */
2221 if (unlikely(!src)) {
2222 void *kaddr = kmap_atomic(dst, KM_USER0);
Linus Torvalds5d2a2db2005-11-29 14:07:55 -08002223 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2224
2225 /*
2226 * This really shouldn't fail, because the page is there
2227 * in the page tables. But it might just be unreadable,
2228 * in which case we just give up and fill the result with
2229 * zeroes.
2230 */
2231 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
Jan Beulich3ecb01d2010-10-26 14:22:27 -07002232 clear_page(kaddr);
Linus Torvalds6aab3412005-11-28 14:34:23 -08002233 kunmap_atomic(kaddr, KM_USER0);
Dmitriy Monakhovc4ec7b02006-10-19 23:29:08 -07002234 flush_dcache_page(dst);
Nick Piggin0ed361d2008-02-04 22:29:34 -08002235 } else
2236 copy_user_highpage(dst, src, va, vma);
Linus Torvalds6aab3412005-11-28 14:34:23 -08002237}
2238
Linus Torvalds1da177e2005-04-16 15:20:36 -07002239/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002240 * This routine handles present pages, when users try to write
2241 * to a shared page. It is done by copying the page to a new address
2242 * and decrementing the shared-page counter for the old page.
2243 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07002244 * Note that this routine assumes that the protection checks have been
2245 * done by the caller (the low-level page fault routine in most cases).
2246 * Thus we can safely just mark it writable once we've done any necessary
2247 * COW.
2248 *
2249 * We also mark the page dirty at this point even though the page will
2250 * change only once the write actually happens. This avoids a few races,
2251 * and potentially makes it more efficient.
2252 *
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002253 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2254 * but allow concurrent faults), with pte both mapped and locked.
2255 * We return with mmap_sem still held, but pte unmapped and unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002256 */
Hugh Dickins65500d22005-10-29 18:15:59 -07002257static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2258 unsigned long address, pte_t *page_table, pmd_t *pmd,
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002259 spinlock_t *ptl, pte_t orig_pte)
Namhyung Kime6219ec2010-10-26 14:22:00 -07002260 __releases(ptl)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002261{
Hugh Dickinse5bbe4d2005-11-29 16:54:51 +00002262 struct page *old_page, *new_page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002263 pte_t entry;
Michel Lespinasseb009c022011-01-13 15:46:07 -08002264 int ret = 0;
Peter Zijlstraa200ee12007-10-08 18:54:37 +02002265 int page_mkwrite = 0;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07002266 struct page *dirty_page = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002267
Linus Torvalds6aab3412005-11-28 14:34:23 -08002268 old_page = vm_normal_page(vma, address, orig_pte);
Peter Zijlstra251b97f2008-07-04 09:59:24 -07002269 if (!old_page) {
2270 /*
2271 * VM_MIXEDMAP !pfn_valid() case
2272 *
2273 * We should not cow pages in a shared writeable mapping.
2274 * Just mark the pages writable as we can't do any dirty
2275 * accounting on raw pfn maps.
2276 */
2277 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2278 (VM_WRITE|VM_SHARED))
2279 goto reuse;
Linus Torvalds6aab3412005-11-28 14:34:23 -08002280 goto gotten;
Peter Zijlstra251b97f2008-07-04 09:59:24 -07002281 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002282
Peter Zijlstrad08b3852006-09-25 23:30:57 -07002283 /*
Peter Zijlstraee6a6452006-09-25 23:31:00 -07002284 * Take out anonymous pages first, anonymous shared vmas are
2285 * not dirty accountable.
Peter Zijlstrad08b3852006-09-25 23:30:57 -07002286 */
Hugh Dickins9a840892009-09-21 17:02:01 -07002287 if (PageAnon(old_page) && !PageKsm(old_page)) {
Hugh Dickinsab967d82009-01-06 14:39:33 -08002288 if (!trylock_page(old_page)) {
2289 page_cache_get(old_page);
2290 pte_unmap_unlock(page_table, ptl);
2291 lock_page(old_page);
2292 page_table = pte_offset_map_lock(mm, pmd, address,
2293 &ptl);
2294 if (!pte_same(*page_table, orig_pte)) {
2295 unlock_page(old_page);
Hugh Dickinsab967d82009-01-06 14:39:33 -08002296 goto unlock;
2297 }
2298 page_cache_release(old_page);
Peter Zijlstraee6a6452006-09-25 23:31:00 -07002299 }
Michel Lespinasseb009c022011-01-13 15:46:07 -08002300 if (reuse_swap_page(old_page)) {
Rik van Rielc44b6742010-03-05 13:42:09 -08002301 /*
2302 * The page is all ours. Move it to our anon_vma so
2303 * the rmap code will not search our parent or siblings.
2304 * Protected against the rmap code by the page lock.
2305 */
2306 page_move_anon_rmap(old_page, vma, address);
Michel Lespinasseb009c022011-01-13 15:46:07 -08002307 unlock_page(old_page);
2308 goto reuse;
2309 }
Hugh Dickinsab967d82009-01-06 14:39:33 -08002310 unlock_page(old_page);
Peter Zijlstraee6a6452006-09-25 23:31:00 -07002311 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
Peter Zijlstrad08b3852006-09-25 23:30:57 -07002312 (VM_WRITE|VM_SHARED))) {
Peter Zijlstraee6a6452006-09-25 23:31:00 -07002313 /*
2314 * Only catch write-faults on shared writable pages,
2315 * read-only shared pages can get COWed by
2316 * get_user_pages(.write=1, .force=1).
2317 */
David Howells9637a5e2006-06-23 02:03:43 -07002318 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
Nick Pigginc2ec1752009-03-31 15:23:21 -07002319 struct vm_fault vmf;
2320 int tmp;
2321
2322 vmf.virtual_address = (void __user *)(address &
2323 PAGE_MASK);
2324 vmf.pgoff = old_page->index;
2325 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2326 vmf.page = old_page;
2327
David Howells9637a5e2006-06-23 02:03:43 -07002328 /*
2329 * Notify the address space that the page is about to
2330 * become writable so that it can prohibit this or wait
2331 * for the page to get into an appropriate state.
2332 *
2333 * We do this without the lock held, so that it can
2334 * sleep if it needs to.
2335 */
2336 page_cache_get(old_page);
2337 pte_unmap_unlock(page_table, ptl);
2338
Nick Pigginc2ec1752009-03-31 15:23:21 -07002339 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
2340 if (unlikely(tmp &
2341 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2342 ret = tmp;
David Howells9637a5e2006-06-23 02:03:43 -07002343 goto unwritable_page;
Nick Pigginc2ec1752009-03-31 15:23:21 -07002344 }
Nick Pigginb827e492009-04-30 15:08:16 -07002345 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
2346 lock_page(old_page);
2347 if (!old_page->mapping) {
2348 ret = 0; /* retry the fault */
2349 unlock_page(old_page);
2350 goto unwritable_page;
2351 }
2352 } else
2353 VM_BUG_ON(!PageLocked(old_page));
David Howells9637a5e2006-06-23 02:03:43 -07002354
David Howells9637a5e2006-06-23 02:03:43 -07002355 /*
2356 * Since we dropped the lock we need to revalidate
2357 * the PTE as someone else may have changed it. If
2358 * they did, we just return, as we can count on the
2359 * MMU to tell us if they didn't also make it writable.
2360 */
2361 page_table = pte_offset_map_lock(mm, pmd, address,
2362 &ptl);
Nick Pigginb827e492009-04-30 15:08:16 -07002363 if (!pte_same(*page_table, orig_pte)) {
2364 unlock_page(old_page);
David Howells9637a5e2006-06-23 02:03:43 -07002365 goto unlock;
Nick Pigginb827e492009-04-30 15:08:16 -07002366 }
Peter Zijlstraa200ee12007-10-08 18:54:37 +02002367
2368 page_mkwrite = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002369 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -07002370 dirty_page = old_page;
2371 get_page(dirty_page);
David Howells9637a5e2006-06-23 02:03:43 -07002372
Peter Zijlstra251b97f2008-07-04 09:59:24 -07002373reuse:
David Howells9637a5e2006-06-23 02:03:43 -07002374 flush_cache_page(vma, address, pte_pfn(orig_pte));
2375 entry = pte_mkyoung(orig_pte);
2376 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
KAMEZAWA Hiroyuki954ffcb2007-10-16 01:25:44 -07002377 if (ptep_set_access_flags(vma, address, page_table, entry,1))
Russell King4b3073e2009-12-18 16:40:18 +00002378 update_mmu_cache(vma, address, page_table);
Michel Lespinasse72ddc8f2011-01-13 15:46:08 -08002379 pte_unmap_unlock(page_table, ptl);
David Howells9637a5e2006-06-23 02:03:43 -07002380 ret |= VM_FAULT_WRITE;
Michel Lespinasse72ddc8f2011-01-13 15:46:08 -08002381
2382 if (!dirty_page)
2383 return ret;
2384
2385 /*
2386 * Yes, Virginia, this is actually required to prevent a race
2387 * with clear_page_dirty_for_io() from clearing the page dirty
2388 * bit after it clear all dirty ptes, but before a racing
2389 * do_wp_page installs a dirty pte.
2390 *
Ryota Ozakia335b2e2011-02-10 13:56:28 +09002391 * __do_fault is protected similarly.
Michel Lespinasse72ddc8f2011-01-13 15:46:08 -08002392 */
2393 if (!page_mkwrite) {
2394 wait_on_page_locked(dirty_page);
2395 set_page_dirty_balance(dirty_page, page_mkwrite);
2396 }
2397 put_page(dirty_page);
2398 if (page_mkwrite) {
2399 struct address_space *mapping = dirty_page->mapping;
2400
2401 set_page_dirty(dirty_page);
2402 unlock_page(dirty_page);
2403 page_cache_release(dirty_page);
2404 if (mapping) {
2405 /*
2406 * Some device drivers do not set page.mapping
2407 * but still dirty their pages
2408 */
2409 balance_dirty_pages_ratelimited(mapping);
2410 }
2411 }
2412
2413 /* file_update_time outside page_lock */
2414 if (vma->vm_file)
2415 file_update_time(vma->vm_file);
2416
2417 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002418 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002419
2420 /*
2421 * Ok, we need to copy. Oh, well..
2422 */
Nick Pigginb5810032005-10-29 18:16:12 -07002423 page_cache_get(old_page);
Hugh Dickins920fc352005-11-21 21:32:17 -08002424gotten:
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002425 pte_unmap_unlock(page_table, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426
2427 if (unlikely(anon_vma_prepare(vma)))
Hugh Dickins65500d22005-10-29 18:15:59 -07002428 goto oom;
Hugh Dickinsa13ea5b2009-09-21 17:03:30 -07002429
Hugh Dickins62eede62009-09-21 17:03:34 -07002430 if (is_zero_pfn(pte_pfn(orig_pte))) {
Hugh Dickinsa13ea5b2009-09-21 17:03:30 -07002431 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2432 if (!new_page)
2433 goto oom;
2434 } else {
2435 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2436 if (!new_page)
2437 goto oom;
2438 cow_user_page(new_page, old_page, address, vma);
2439 }
2440 __SetPageUptodate(new_page);
2441
KAMEZAWA Hiroyuki2c26fdd2009-01-07 18:08:10 -08002442 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
Balbir Singh8a9f3cc2008-02-07 00:13:53 -08002443 goto oom_free_new;
2444
Linus Torvalds1da177e2005-04-16 15:20:36 -07002445 /*
2446 * Re-check the pte - we dropped the lock
2447 */
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002448 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
Hugh Dickins65500d22005-10-29 18:15:59 -07002449 if (likely(pte_same(*page_table, orig_pte))) {
Hugh Dickins920fc352005-11-21 21:32:17 -08002450 if (old_page) {
Hugh Dickins920fc352005-11-21 21:32:17 -08002451 if (!PageAnon(old_page)) {
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -08002452 dec_mm_counter_fast(mm, MM_FILEPAGES);
2453 inc_mm_counter_fast(mm, MM_ANONPAGES);
Hugh Dickins920fc352005-11-21 21:32:17 -08002454 }
2455 } else
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -08002456 inc_mm_counter_fast(mm, MM_ANONPAGES);
Ben Collinseca35132005-11-29 11:45:26 -08002457 flush_cache_page(vma, address, pte_pfn(orig_pte));
Hugh Dickins65500d22005-10-29 18:15:59 -07002458 entry = mk_pte(new_page, vma->vm_page_prot);
2459 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
Siddha, Suresh B4ce072f2006-09-29 01:58:42 -07002460 /*
2461 * Clear the pte entry and flush it first, before updating the
2462 * pte with the new entry. This will avoid a race condition
2463 * seen in the presence of one thread doing SMC and another
2464 * thread doing COW.
2465 */
Izik Eidus828502d2009-09-21 17:01:51 -07002466 ptep_clear_flush(vma, address, page_table);
Nick Piggin9617d952006-01-06 00:11:12 -08002467 page_add_new_anon_rmap(new_page, vma, address);
Izik Eidus828502d2009-09-21 17:01:51 -07002468 /*
2469 * We call the notify macro here because, when using secondary
2470 * mmu page tables (such as kvm shadow page tables), we want the
2471 * new page to be mapped directly into the secondary page table.
2472 */
2473 set_pte_at_notify(mm, address, page_table, entry);
Russell King4b3073e2009-12-18 16:40:18 +00002474 update_mmu_cache(vma, address, page_table);
Nick Piggin945754a2008-06-23 14:30:30 +02002475 if (old_page) {
2476 /*
2477 * Only after switching the pte to the new page may
2478 * we remove the mapcount here. Otherwise another
2479 * process may come and find the rmap count decremented
2480 * before the pte is switched to the new page, and
2481 * "reuse" the old page writing into it while our pte
2482 * here still points into it and can be read by other
2483 * threads.
2484 *
2485 * The critical issue is to order this
2486 * page_remove_rmap with the ptp_clear_flush above.
2487 * Those stores are ordered by (if nothing else,)
2488 * the barrier present in the atomic_add_negative
2489 * in page_remove_rmap.
2490 *
2491 * Then the TLB flush in ptep_clear_flush ensures that
2492 * no process can access the old page before the
2493 * decremented mapcount is visible. And the old page
2494 * cannot be reused until after the decremented
2495 * mapcount is visible. So transitively, TLBs to
2496 * old page will be flushed before it can be reused.
2497 */
Hugh Dickinsedc315f2009-01-06 14:40:11 -08002498 page_remove_rmap(old_page);
Nick Piggin945754a2008-06-23 14:30:30 +02002499 }
2500
Linus Torvalds1da177e2005-04-16 15:20:36 -07002501 /* Free the old page.. */
2502 new_page = old_page;
Nick Pigginf33ea7f2005-08-03 20:24:01 +10002503 ret |= VM_FAULT_WRITE;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -08002504 } else
2505 mem_cgroup_uncharge_page(new_page);
2506
Hugh Dickins920fc352005-11-21 21:32:17 -08002507 if (new_page)
2508 page_cache_release(new_page);
Hugh Dickins65500d22005-10-29 18:15:59 -07002509unlock:
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002510 pte_unmap_unlock(page_table, ptl);
Michel Lespinassee15f8c02011-02-10 15:01:32 -08002511 if (old_page) {
2512 /*
2513 * Don't let another task, with possibly unlocked vma,
2514 * keep the mlocked page.
2515 */
2516 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2517 lock_page(old_page); /* LRU manipulation */
2518 munlock_vma_page(old_page);
2519 unlock_page(old_page);
2520 }
2521 page_cache_release(old_page);
2522 }
Nick Pigginf33ea7f2005-08-03 20:24:01 +10002523 return ret;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -08002524oom_free_new:
Hugh Dickins6dbf6d32008-03-04 14:29:04 -08002525 page_cache_release(new_page);
Hugh Dickins65500d22005-10-29 18:15:59 -07002526oom:
Nick Pigginb827e492009-04-30 15:08:16 -07002527 if (old_page) {
2528 if (page_mkwrite) {
2529 unlock_page(old_page);
2530 page_cache_release(old_page);
2531 }
Hugh Dickins920fc352005-11-21 21:32:17 -08002532 page_cache_release(old_page);
Nick Pigginb827e492009-04-30 15:08:16 -07002533 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002534 return VM_FAULT_OOM;
David Howells9637a5e2006-06-23 02:03:43 -07002535
2536unwritable_page:
2537 page_cache_release(old_page);
Nick Pigginc2ec1752009-03-31 15:23:21 -07002538 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002539}
2540
2541/*
2542 * Helper functions for unmap_mapping_range().
2543 *
2544 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
2545 *
2546 * We have to restart searching the prio_tree whenever we drop the lock,
2547 * since the iterator is only valid while the lock is held, and anyway
2548 * a later vma might be split and reinserted earlier while lock dropped.
2549 *
2550 * The list of nonlinear vmas could be handled more efficiently, using
2551 * a placeholder, but handle it in the same way until a need is shown.
2552 * It is important to search the prio_tree before nonlinear list: a vma
2553 * may become nonlinear and be shifted from prio_tree to nonlinear list
2554 * while the lock is dropped; but never shifted from list to prio_tree.
2555 *
2556 * In order to make forward progress despite restarting the search,
2557 * vm_truncate_count is used to mark a vma as now dealt with, so we can
2558 * quickly skip it next time around. Since the prio_tree search only
2559 * shows us those vmas affected by unmapping the range in question, we
2560 * can't efficiently keep all vmas in step with mapping->truncate_count:
2561 * so instead reset them all whenever it wraps back to 0 (then go to 1).
2562 * mapping->truncate_count and vma->vm_truncate_count are protected by
2563 * i_mmap_lock.
2564 *
2565 * In order to make forward progress despite repeatedly restarting some
Hugh Dickinsee39b372005-04-19 13:29:15 -07002566 * large vma, note the restart_addr from unmap_vmas when it breaks out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002567 * and restart from that address when we reach that vma again. It might
2568 * have been split or merged, shrunk or extended, but never shifted: so
2569 * restart_addr remains valid so long as it remains in the vma's range.
2570 * unmap_mapping_range forces truncate_count to leap over page-aligned
2571 * values so we can save vma's restart_addr in its truncate_count field.
2572 */
2573#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
2574
2575static void reset_vma_truncate_counts(struct address_space *mapping)
2576{
2577 struct vm_area_struct *vma;
2578 struct prio_tree_iter iter;
2579
2580 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
2581 vma->vm_truncate_count = 0;
2582 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
2583 vma->vm_truncate_count = 0;
2584}
2585
2586static int unmap_mapping_range_vma(struct vm_area_struct *vma,
2587 unsigned long start_addr, unsigned long end_addr,
2588 struct zap_details *details)
2589{
2590 unsigned long restart_addr;
2591 int need_break;
2592
Nick Piggind00806b2007-07-19 01:46:57 -07002593 /*
2594 * files that support invalidating or truncating portions of the
Nick Piggind0217ac2007-07-19 01:47:03 -07002595 * file from under mmaped areas must have their ->fault function
Nick Piggin83c54072007-07-19 01:47:05 -07002596 * return a locked page (and set VM_FAULT_LOCKED in the return).
2597 * This provides synchronisation against concurrent unmapping here.
Nick Piggind00806b2007-07-19 01:46:57 -07002598 */
Nick Piggind00806b2007-07-19 01:46:57 -07002599
Linus Torvalds1da177e2005-04-16 15:20:36 -07002600again:
2601 restart_addr = vma->vm_truncate_count;
2602 if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
2603 start_addr = restart_addr;
2604 if (start_addr >= end_addr) {
2605 /* Top of vma has been split off since last time */
2606 vma->vm_truncate_count = details->truncate_count;
2607 return 0;
2608 }
2609 }
2610
Hugh Dickinsee39b372005-04-19 13:29:15 -07002611 restart_addr = zap_page_range(vma, start_addr,
2612 end_addr - start_addr, details);
Nick Piggin95c354f2008-01-30 13:31:20 +01002613 need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002614
Hugh Dickinsee39b372005-04-19 13:29:15 -07002615 if (restart_addr >= end_addr) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002616 /* We have now completed this vma: mark it so */
2617 vma->vm_truncate_count = details->truncate_count;
2618 if (!need_break)
2619 return 0;
2620 } else {
2621 /* Note restart_addr in vma's truncate_count field */
Hugh Dickinsee39b372005-04-19 13:29:15 -07002622 vma->vm_truncate_count = restart_addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002623 if (!need_break)
2624 goto again;
2625 }
2626
2627 spin_unlock(details->i_mmap_lock);
2628 cond_resched();
2629 spin_lock(details->i_mmap_lock);
2630 return -EINTR;
2631}
2632
2633static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
2634 struct zap_details *details)
2635{
2636 struct vm_area_struct *vma;
2637 struct prio_tree_iter iter;
2638 pgoff_t vba, vea, zba, zea;
2639
2640restart:
2641 vma_prio_tree_foreach(vma, &iter, root,
2642 details->first_index, details->last_index) {
2643 /* Skip quickly over those we have already dealt with */
2644 if (vma->vm_truncate_count == details->truncate_count)
2645 continue;
2646
2647 vba = vma->vm_pgoff;
2648 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
2649 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2650 zba = details->first_index;
2651 if (zba < vba)
2652 zba = vba;
2653 zea = details->last_index;
2654 if (zea > vea)
2655 zea = vea;
2656
2657 if (unmap_mapping_range_vma(vma,
2658 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2659 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2660 details) < 0)
2661 goto restart;
2662 }
2663}
2664
2665static inline void unmap_mapping_range_list(struct list_head *head,
2666 struct zap_details *details)
2667{
2668 struct vm_area_struct *vma;
2669
2670 /*
2671 * In nonlinear VMAs there is no correspondence between virtual address
2672 * offset and file offset. So we must perform an exhaustive search
2673 * across *all* the pages in each nonlinear VMA, not just the pages
2674 * whose virtual address lies outside the file truncation point.
2675 */
2676restart:
2677 list_for_each_entry(vma, head, shared.vm_set.list) {
2678 /* Skip quickly over those we have already dealt with */
2679 if (vma->vm_truncate_count == details->truncate_count)
2680 continue;
2681 details->nonlinear_vma = vma;
2682 if (unmap_mapping_range_vma(vma, vma->vm_start,
2683 vma->vm_end, details) < 0)
2684 goto restart;
2685 }
2686}
2687
2688/**
Robert P. J. Day72fd4a32007-02-10 01:45:59 -08002689 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
Martin Waitz3d410882005-06-23 22:05:21 -07002690 * @mapping: the address space containing mmaps to be unmapped.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002691 * @holebegin: byte in first page to unmap, relative to the start of
2692 * the underlying file. This will be rounded down to a PAGE_SIZE
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +10002693 * boundary. Note that this is different from truncate_pagecache(), which
Linus Torvalds1da177e2005-04-16 15:20:36 -07002694 * must keep the partial page. In contrast, we must get rid of
2695 * partial pages.
2696 * @holelen: size of prospective hole in bytes. This will be rounded
2697 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2698 * end of the file.
2699 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2700 * but 0 when invalidating pagecache, don't throw away private data.
2701 */
2702void unmap_mapping_range(struct address_space *mapping,
2703 loff_t const holebegin, loff_t const holelen, int even_cows)
2704{
2705 struct zap_details details;
2706 pgoff_t hba = holebegin >> PAGE_SHIFT;
2707 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2708
2709 /* Check for overflow. */
2710 if (sizeof(holelen) > sizeof(hlen)) {
2711 long long holeend =
2712 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2713 if (holeend & ~(long long)ULONG_MAX)
2714 hlen = ULONG_MAX - hba + 1;
2715 }
2716
2717 details.check_mapping = even_cows? NULL: mapping;
2718 details.nonlinear_vma = NULL;
2719 details.first_index = hba;
2720 details.last_index = hba + hlen - 1;
2721 if (details.last_index < details.first_index)
2722 details.last_index = ULONG_MAX;
2723 details.i_mmap_lock = &mapping->i_mmap_lock;
2724
Miklos Szeredi2aa15892011-02-23 13:49:47 +01002725 mutex_lock(&mapping->unmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002726 spin_lock(&mapping->i_mmap_lock);
2727
Nick Piggind00806b2007-07-19 01:46:57 -07002728 /* Protect against endless unmapping loops */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002729 mapping->truncate_count++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002730 if (unlikely(is_restart_addr(mapping->truncate_count))) {
2731 if (mapping->truncate_count == 0)
2732 reset_vma_truncate_counts(mapping);
2733 mapping->truncate_count++;
2734 }
2735 details.truncate_count = mapping->truncate_count;
2736
2737 if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
2738 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2739 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
2740 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
2741 spin_unlock(&mapping->i_mmap_lock);
Miklos Szeredi2aa15892011-02-23 13:49:47 +01002742 mutex_unlock(&mapping->unmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002743}
2744EXPORT_SYMBOL(unmap_mapping_range);
2745
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002746int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
2747{
2748 struct address_space *mapping = inode->i_mapping;
2749
2750 /*
2751 * If the underlying filesystem is not going to provide
2752 * a way to truncate a range of blocks (punch a hole) -
2753 * we should return failure right now.
2754 */
Al Viroacfa4382008-12-04 10:06:33 -05002755 if (!inode->i_op->truncate_range)
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002756 return -ENOSYS;
2757
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002758 mutex_lock(&inode->i_mutex);
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002759 down_write(&inode->i_alloc_sem);
2760 unmap_mapping_range(mapping, offset, (end - offset), 1);
2761 truncate_inode_pages_range(mapping, offset, end);
Nick Piggind00806b2007-07-19 01:46:57 -07002762 unmap_mapping_range(mapping, offset, (end - offset), 1);
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002763 inode->i_op->truncate_range(inode, offset, end);
2764 up_write(&inode->i_alloc_sem);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002765 mutex_unlock(&inode->i_mutex);
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002766
2767 return 0;
2768}
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002769
Linus Torvalds1da177e2005-04-16 15:20:36 -07002770/*
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002771 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2772 * but allow concurrent faults), and pte mapped but not yet locked.
2773 * We return with mmap_sem still held, but pte unmapped and unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002774 */
Hugh Dickins65500d22005-10-29 18:15:59 -07002775static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
2776 unsigned long address, pte_t *page_table, pmd_t *pmd,
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07002777 unsigned int flags, pte_t orig_pte)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002778{
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002779 spinlock_t *ptl;
Andrea Arcangeli4969c112010-09-09 16:37:52 -07002780 struct page *page, *swapcache = NULL;
Hugh Dickins65500d22005-10-29 18:15:59 -07002781 swp_entry_t entry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002782 pte_t pte;
Michel Lespinassed065bd82010-10-26 14:21:57 -07002783 int locked;
KAMEZAWA Hiroyuki56039ef2011-03-23 16:42:19 -07002784 struct mem_cgroup *ptr;
Rik van Rielad8c2ee2010-08-09 17:19:48 -07002785 int exclusive = 0;
Nick Piggin83c54072007-07-19 01:47:05 -07002786 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002787
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07002788 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002789 goto out;
Hugh Dickins65500d22005-10-29 18:15:59 -07002790
2791 entry = pte_to_swp_entry(orig_pte);
Andi Kleend1737fd2009-09-16 11:50:06 +02002792 if (unlikely(non_swap_entry(entry))) {
2793 if (is_migration_entry(entry)) {
2794 migration_entry_wait(mm, pmd, address);
2795 } else if (is_hwpoison_entry(entry)) {
2796 ret = VM_FAULT_HWPOISON;
2797 } else {
2798 print_bad_pte(vma, address, orig_pte, NULL);
Hugh Dickinsd99be1a2009-12-14 17:59:04 -08002799 ret = VM_FAULT_SIGBUS;
Andi Kleend1737fd2009-09-16 11:50:06 +02002800 }
Christoph Lameter06972122006-06-23 02:03:35 -07002801 goto out;
2802 }
Shailabh Nagar0ff92242006-07-14 00:24:37 -07002803 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002804 page = lookup_swap_cache(entry);
2805 if (!page) {
Hugh Dickinsa5c9b692009-06-23 12:36:58 -07002806 grab_swap_token(mm); /* Contend for token _before_ read-in */
Hugh Dickins02098fe2008-02-04 22:28:42 -08002807 page = swapin_readahead(entry,
2808 GFP_HIGHUSER_MOVABLE, vma, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002809 if (!page) {
2810 /*
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002811 * Back out if somebody else faulted in this pte
2812 * while we released the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002813 */
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002814 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002815 if (likely(pte_same(*page_table, orig_pte)))
2816 ret = VM_FAULT_OOM;
Shailabh Nagar0ff92242006-07-14 00:24:37 -07002817 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
Hugh Dickins65500d22005-10-29 18:15:59 -07002818 goto unlock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002819 }
2820
2821 /* Had to read the page from swap area: Major fault */
2822 ret = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07002823 count_vm_event(PGMAJFAULT);
Andi Kleend1737fd2009-09-16 11:50:06 +02002824 } else if (PageHWPoison(page)) {
Wu Fengguang71f72522009-12-16 12:19:58 +01002825 /*
2826 * hwpoisoned dirty swapcache pages are kept for killing
2827 * owner processes (which may be unknown at hwpoison time)
2828 */
Andi Kleend1737fd2009-09-16 11:50:06 +02002829 ret = VM_FAULT_HWPOISON;
2830 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
Andi Kleen4779cb32009-10-14 01:51:41 +02002831 goto out_release;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002832 }
2833
Michel Lespinassed065bd82010-10-26 14:21:57 -07002834 locked = lock_page_or_retry(page, mm, flags);
Balbir Singh20a10222007-11-14 17:00:33 -08002835 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
Michel Lespinassed065bd82010-10-26 14:21:57 -07002836 if (!locked) {
2837 ret |= VM_FAULT_RETRY;
2838 goto out_release;
2839 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002840
Andrea Arcangeli4969c112010-09-09 16:37:52 -07002841 /*
Hugh Dickins31c4a3d2010-09-19 19:40:22 -07002842 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2843 * release the swapcache from under us. The page pin, and pte_same
2844 * test below, are not enough to exclude that. Even if it is still
2845 * swapcache, we need to check that the page's swap has not changed.
Andrea Arcangeli4969c112010-09-09 16:37:52 -07002846 */
Hugh Dickins31c4a3d2010-09-19 19:40:22 -07002847 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
Andrea Arcangeli4969c112010-09-09 16:37:52 -07002848 goto out_page;
2849
2850 if (ksm_might_need_to_copy(page, vma, address)) {
2851 swapcache = page;
2852 page = ksm_does_need_to_copy(page, vma, address);
2853
2854 if (unlikely(!page)) {
2855 ret = VM_FAULT_OOM;
2856 page = swapcache;
2857 swapcache = NULL;
2858 goto out_page;
2859 }
Hugh Dickins5ad64682009-12-14 17:59:24 -08002860 }
2861
KAMEZAWA Hiroyuki2c26fdd2009-01-07 18:08:10 -08002862 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
KAMEZAWA Hiroyuki073e5872008-10-18 20:28:08 -07002863 ret = VM_FAULT_OOM;
Johannes Weinerbc43f752009-04-30 15:08:08 -07002864 goto out_page;
KAMEZAWA Hiroyuki073e5872008-10-18 20:28:08 -07002865 }
2866
Linus Torvalds1da177e2005-04-16 15:20:36 -07002867 /*
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002868 * Back out if somebody else already faulted in this pte.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002869 */
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002870 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
Hugh Dickins9e9bef02005-10-29 18:16:15 -07002871 if (unlikely(!pte_same(*page_table, orig_pte)))
Kirill Korotaevb8107482005-05-16 21:53:50 -07002872 goto out_nomap;
Kirill Korotaevb8107482005-05-16 21:53:50 -07002873
2874 if (unlikely(!PageUptodate(page))) {
2875 ret = VM_FAULT_SIGBUS;
2876 goto out_nomap;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002877 }
2878
KAMEZAWA Hiroyuki8c7c6e32009-01-07 18:08:00 -08002879 /*
2880 * The page isn't present yet, go ahead with the fault.
2881 *
2882 * Be careful about the sequence of operations here.
2883 * To get its accounting right, reuse_swap_page() must be called
2884 * while the page is counted on swap but not yet in mapcount i.e.
2885 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2886 * must be called after the swap_free(), or it will never succeed.
KAMEZAWA Hiroyuki03f3c432009-01-07 18:08:31 -08002887 * Because delete_from_swap_page() may be called by reuse_swap_page(),
2888 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
2889 * in page->private. In this case, a record in swap_cgroup is silently
2890 * discarded at swap_free().
KAMEZAWA Hiroyuki8c7c6e32009-01-07 18:08:00 -08002891 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002892
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -08002893 inc_mm_counter_fast(mm, MM_ANONPAGES);
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -08002894 dec_mm_counter_fast(mm, MM_SWAPENTS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002895 pte = mk_pte(page, vma->vm_page_prot);
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07002896 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002897 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07002898 flags &= ~FAULT_FLAG_WRITE;
Andrea Arcangeli9a5b4892010-08-09 17:19:49 -07002899 ret |= VM_FAULT_WRITE;
Rik van Rielad8c2ee2010-08-09 17:19:48 -07002900 exclusive = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002901 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002902 flush_icache_page(vma, page);
2903 set_pte_at(mm, address, page_table, pte);
Rik van Rielad8c2ee2010-08-09 17:19:48 -07002904 do_page_add_anon_rmap(page, vma, address, exclusive);
KAMEZAWA Hiroyuki03f3c432009-01-07 18:08:31 -08002905 /* It's better to call commit-charge after rmap is established */
2906 mem_cgroup_commit_charge_swapin(page, ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002907
Hugh Dickinsc475a8a2005-06-21 17:15:12 -07002908 swap_free(entry);
Nick Pigginb291f002008-10-18 20:26:44 -07002909 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
Hugh Dickinsa2c43ee2009-01-06 14:39:36 -08002910 try_to_free_swap(page);
Hugh Dickinsc475a8a2005-06-21 17:15:12 -07002911 unlock_page(page);
Andrea Arcangeli4969c112010-09-09 16:37:52 -07002912 if (swapcache) {
2913 /*
2914 * Hold the lock to avoid the swap entry to be reused
2915 * until we take the PT lock for the pte_same() check
2916 * (to avoid false positives from pte_same). For
2917 * further safety release the lock after the swap_free
2918 * so that the swap count won't change under a
2919 * parallel locked swapcache.
2920 */
2921 unlock_page(swapcache);
2922 page_cache_release(swapcache);
2923 }
Hugh Dickinsc475a8a2005-06-21 17:15:12 -07002924
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07002925 if (flags & FAULT_FLAG_WRITE) {
Hugh Dickins61469f12008-03-04 14:29:04 -08002926 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
2927 if (ret & VM_FAULT_ERROR)
2928 ret &= VM_FAULT_ERROR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002929 goto out;
2930 }
2931
2932 /* No need to invalidate - it was non-present before */
Russell King4b3073e2009-12-18 16:40:18 +00002933 update_mmu_cache(vma, address, page_table);
Hugh Dickins65500d22005-10-29 18:15:59 -07002934unlock:
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002935 pte_unmap_unlock(page_table, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002936out:
2937 return ret;
Kirill Korotaevb8107482005-05-16 21:53:50 -07002938out_nomap:
KAMEZAWA Hiroyuki7a81b882009-01-07 18:07:48 -08002939 mem_cgroup_cancel_charge_swapin(ptr);
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002940 pte_unmap_unlock(page_table, ptl);
Johannes Weinerbc43f752009-04-30 15:08:08 -07002941out_page:
Kirill Korotaevb8107482005-05-16 21:53:50 -07002942 unlock_page(page);
Andi Kleen4779cb32009-10-14 01:51:41 +02002943out_release:
Kirill Korotaevb8107482005-05-16 21:53:50 -07002944 page_cache_release(page);
Andrea Arcangeli4969c112010-09-09 16:37:52 -07002945 if (swapcache) {
2946 unlock_page(swapcache);
2947 page_cache_release(swapcache);
2948 }
Hugh Dickins65500d22005-10-29 18:15:59 -07002949 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002950}
2951
2952/*
Luck, Tony8ca3eb02010-08-24 11:44:18 -07002953 * This is like a special single-page "expand_{down|up}wards()",
2954 * except we must first make sure that 'address{-|+}PAGE_SIZE'
Linus Torvalds320b2b82010-08-12 17:54:33 -07002955 * doesn't hit another vma.
Linus Torvalds320b2b82010-08-12 17:54:33 -07002956 */
2957static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
2958{
2959 address &= PAGE_MASK;
2960 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
Linus Torvalds0e8e50e2010-08-20 16:49:40 -07002961 struct vm_area_struct *prev = vma->vm_prev;
Linus Torvalds320b2b82010-08-12 17:54:33 -07002962
Linus Torvalds0e8e50e2010-08-20 16:49:40 -07002963 /*
2964 * Is there a mapping abutting this one below?
2965 *
2966 * That's only ok if it's the same stack mapping
2967 * that has gotten split..
2968 */
2969 if (prev && prev->vm_end == address)
2970 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2971
2972 expand_stack(vma, address - PAGE_SIZE);
Linus Torvalds320b2b82010-08-12 17:54:33 -07002973 }
Luck, Tony8ca3eb02010-08-24 11:44:18 -07002974 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
2975 struct vm_area_struct *next = vma->vm_next;
2976
2977 /* As VM_GROWSDOWN but s/below/above/ */
2978 if (next && next->vm_start == address + PAGE_SIZE)
2979 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
2980
2981 expand_upwards(vma, address + PAGE_SIZE);
2982 }
Linus Torvalds320b2b82010-08-12 17:54:33 -07002983 return 0;
2984}
2985
2986/*
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002987 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2988 * but allow concurrent faults), and pte mapped but not yet locked.
2989 * We return with mmap_sem still held, but pte unmapped and unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002990 */
Hugh Dickins65500d22005-10-29 18:15:59 -07002991static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
2992 unsigned long address, pte_t *page_table, pmd_t *pmd,
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07002993 unsigned int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002994{
Hugh Dickins8f4e2102005-10-29 18:16:26 -07002995 struct page *page;
2996 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002997 pte_t entry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002998
Linus Torvalds11ac5522010-08-14 11:44:56 -07002999 pte_unmap(page_table);
Linus Torvalds320b2b82010-08-12 17:54:33 -07003000
Linus Torvalds11ac5522010-08-14 11:44:56 -07003001 /* Check if we need to add a guard page to the stack */
3002 if (check_stack_guard_page(vma, address) < 0)
3003 return VM_FAULT_SIGBUS;
3004
3005 /* Use the zero-page for reads */
Hugh Dickins62eede62009-09-21 17:03:34 -07003006 if (!(flags & FAULT_FLAG_WRITE)) {
3007 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3008 vma->vm_page_prot));
Linus Torvalds11ac5522010-08-14 11:44:56 -07003009 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
Hugh Dickinsa13ea5b2009-09-21 17:03:30 -07003010 if (!pte_none(*page_table))
3011 goto unlock;
3012 goto setpte;
3013 }
3014
Nick Piggin557ed1f2007-10-16 01:24:40 -07003015 /* Allocate our own private page. */
Nick Piggin557ed1f2007-10-16 01:24:40 -07003016 if (unlikely(anon_vma_prepare(vma)))
3017 goto oom;
3018 page = alloc_zeroed_user_highpage_movable(vma, address);
3019 if (!page)
3020 goto oom;
Nick Piggin0ed361d2008-02-04 22:29:34 -08003021 __SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003022
KAMEZAWA Hiroyuki2c26fdd2009-01-07 18:08:10 -08003023 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
Balbir Singh8a9f3cc2008-02-07 00:13:53 -08003024 goto oom_free_page;
3025
Nick Piggin557ed1f2007-10-16 01:24:40 -07003026 entry = mk_pte(page, vma->vm_page_prot);
Hugh Dickins1ac0cb52009-09-21 17:03:29 -07003027 if (vma->vm_flags & VM_WRITE)
3028 entry = pte_mkwrite(pte_mkdirty(entry));
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003029
Nick Piggin557ed1f2007-10-16 01:24:40 -07003030 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
Andrea Arcangeli1c2fb7a2009-09-21 17:02:22 -07003031 if (!pte_none(*page_table))
Nick Piggin557ed1f2007-10-16 01:24:40 -07003032 goto release;
Hugh Dickins9ba69292009-09-21 17:02:20 -07003033
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -08003034 inc_mm_counter_fast(mm, MM_ANONPAGES);
Nick Piggin557ed1f2007-10-16 01:24:40 -07003035 page_add_new_anon_rmap(page, vma, address);
Hugh Dickinsa13ea5b2009-09-21 17:03:30 -07003036setpte:
Hugh Dickins65500d22005-10-29 18:15:59 -07003037 set_pte_at(mm, address, page_table, entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003038
3039 /* No need to invalidate - it was non-present before */
Russell King4b3073e2009-12-18 16:40:18 +00003040 update_mmu_cache(vma, address, page_table);
Hugh Dickins65500d22005-10-29 18:15:59 -07003041unlock:
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003042 pte_unmap_unlock(page_table, ptl);
Nick Piggin83c54072007-07-19 01:47:05 -07003043 return 0;
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003044release:
Balbir Singh8a9f3cc2008-02-07 00:13:53 -08003045 mem_cgroup_uncharge_page(page);
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003046 page_cache_release(page);
3047 goto unlock;
Balbir Singh8a9f3cc2008-02-07 00:13:53 -08003048oom_free_page:
Hugh Dickins6dbf6d32008-03-04 14:29:04 -08003049 page_cache_release(page);
Hugh Dickins65500d22005-10-29 18:15:59 -07003050oom:
Linus Torvalds1da177e2005-04-16 15:20:36 -07003051 return VM_FAULT_OOM;
3052}
3053
3054/*
Nick Piggin54cb8822007-07-19 01:46:59 -07003055 * __do_fault() tries to create a new page mapping. It aggressively
Linus Torvalds1da177e2005-04-16 15:20:36 -07003056 * tries to share with existing pages, but makes a separate copy if
Nick Piggin54cb8822007-07-19 01:46:59 -07003057 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
3058 * the next page fault.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003059 *
3060 * As this is called only for pages that do not currently exist, we
3061 * do not need to flush old virtual caches or the TLB.
3062 *
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003063 * We enter with non-exclusive mmap_sem (to exclude vma changes,
Hugh Dickins16abfa02007-10-04 16:56:06 +01003064 * but allow concurrent faults), and pte neither mapped nor locked.
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003065 * We return with mmap_sem still held, but pte unmapped and unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003066 */
Nick Piggin54cb8822007-07-19 01:46:59 -07003067static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
Hugh Dickins16abfa02007-10-04 16:56:06 +01003068 unsigned long address, pmd_t *pmd,
Nick Piggin54cb8822007-07-19 01:46:59 -07003069 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003070{
Hugh Dickins16abfa02007-10-04 16:56:06 +01003071 pte_t *page_table;
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003072 spinlock_t *ptl;
Nick Piggind0217ac2007-07-19 01:47:03 -07003073 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003074 pte_t entry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003075 int anon = 0;
KAMEZAWA Hiroyuki5b4e6552008-10-18 20:28:10 -07003076 int charged = 0;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07003077 struct page *dirty_page = NULL;
Nick Piggind0217ac2007-07-19 01:47:03 -07003078 struct vm_fault vmf;
3079 int ret;
Peter Zijlstraa200ee12007-10-08 18:54:37 +02003080 int page_mkwrite = 0;
Nick Piggin54cb8822007-07-19 01:46:59 -07003081
Nick Piggind0217ac2007-07-19 01:47:03 -07003082 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3083 vmf.pgoff = pgoff;
3084 vmf.flags = flags;
3085 vmf.page = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003086
Nick Piggin3c18ddd2008-04-28 02:12:10 -07003087 ret = vma->vm_ops->fault(vma, &vmf);
Michel Lespinassed065bd82010-10-26 14:21:57 -07003088 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3089 VM_FAULT_RETRY)))
Nick Piggin3c18ddd2008-04-28 02:12:10 -07003090 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003091
Andi Kleena3b947e2009-09-16 11:50:08 +02003092 if (unlikely(PageHWPoison(vmf.page))) {
3093 if (ret & VM_FAULT_LOCKED)
3094 unlock_page(vmf.page);
3095 return VM_FAULT_HWPOISON;
3096 }
3097
Nick Piggind00806b2007-07-19 01:46:57 -07003098 /*
Nick Piggind0217ac2007-07-19 01:47:03 -07003099 * For consistency in subsequent calls, make the faulted page always
Nick Piggind00806b2007-07-19 01:46:57 -07003100 * locked.
3101 */
Nick Piggin83c54072007-07-19 01:47:05 -07003102 if (unlikely(!(ret & VM_FAULT_LOCKED)))
Nick Piggind0217ac2007-07-19 01:47:03 -07003103 lock_page(vmf.page);
Nick Piggin54cb8822007-07-19 01:46:59 -07003104 else
Nick Piggind0217ac2007-07-19 01:47:03 -07003105 VM_BUG_ON(!PageLocked(vmf.page));
Nick Piggind00806b2007-07-19 01:46:57 -07003106
Linus Torvalds1da177e2005-04-16 15:20:36 -07003107 /*
3108 * Should we do an early C-O-W break?
3109 */
Nick Piggind0217ac2007-07-19 01:47:03 -07003110 page = vmf.page;
Nick Piggin54cb8822007-07-19 01:46:59 -07003111 if (flags & FAULT_FLAG_WRITE) {
David Howells9637a5e2006-06-23 02:03:43 -07003112 if (!(vma->vm_flags & VM_SHARED)) {
Nick Piggin54cb8822007-07-19 01:46:59 -07003113 anon = 1;
Nick Piggind00806b2007-07-19 01:46:57 -07003114 if (unlikely(anon_vma_prepare(vma))) {
Nick Piggind0217ac2007-07-19 01:47:03 -07003115 ret = VM_FAULT_OOM;
Nick Piggin54cb8822007-07-19 01:46:59 -07003116 goto out;
Nick Piggind00806b2007-07-19 01:46:57 -07003117 }
Nick Piggin83c54072007-07-19 01:47:05 -07003118 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
3119 vma, address);
Nick Piggind00806b2007-07-19 01:46:57 -07003120 if (!page) {
Nick Piggind0217ac2007-07-19 01:47:03 -07003121 ret = VM_FAULT_OOM;
Nick Piggin54cb8822007-07-19 01:46:59 -07003122 goto out;
Nick Piggind00806b2007-07-19 01:46:57 -07003123 }
KAMEZAWA Hiroyuki2c26fdd2009-01-07 18:08:10 -08003124 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
KAMEZAWA Hiroyuki5b4e6552008-10-18 20:28:10 -07003125 ret = VM_FAULT_OOM;
3126 page_cache_release(page);
3127 goto out;
3128 }
3129 charged = 1;
Nick Piggind0217ac2007-07-19 01:47:03 -07003130 copy_user_highpage(page, vmf.page, address, vma);
Nick Piggin0ed361d2008-02-04 22:29:34 -08003131 __SetPageUptodate(page);
David Howells9637a5e2006-06-23 02:03:43 -07003132 } else {
Nick Piggin54cb8822007-07-19 01:46:59 -07003133 /*
3134 * If the page will be shareable, see if the backing
David Howells9637a5e2006-06-23 02:03:43 -07003135 * address space wants to know that the page is about
Nick Piggin54cb8822007-07-19 01:46:59 -07003136 * to become writable
3137 */
Mark Fasheh69676142007-07-19 01:47:00 -07003138 if (vma->vm_ops->page_mkwrite) {
Nick Pigginc2ec1752009-03-31 15:23:21 -07003139 int tmp;
3140
Mark Fasheh69676142007-07-19 01:47:00 -07003141 unlock_page(page);
Nick Pigginb827e492009-04-30 15:08:16 -07003142 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
Nick Pigginc2ec1752009-03-31 15:23:21 -07003143 tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
3144 if (unlikely(tmp &
3145 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3146 ret = tmp;
Nick Pigginb827e492009-04-30 15:08:16 -07003147 goto unwritable_page;
Mark Fasheh69676142007-07-19 01:47:00 -07003148 }
Nick Pigginb827e492009-04-30 15:08:16 -07003149 if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
3150 lock_page(page);
3151 if (!page->mapping) {
3152 ret = 0; /* retry the fault */
3153 unlock_page(page);
3154 goto unwritable_page;
3155 }
3156 } else
3157 VM_BUG_ON(!PageLocked(page));
Peter Zijlstraa200ee12007-10-08 18:54:37 +02003158 page_mkwrite = 1;
David Howells9637a5e2006-06-23 02:03:43 -07003159 }
3160 }
Nick Piggin54cb8822007-07-19 01:46:59 -07003161
Linus Torvalds1da177e2005-04-16 15:20:36 -07003162 }
3163
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003164 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003165
3166 /*
3167 * This silly early PAGE_DIRTY setting removes a race
3168 * due to the bad i386 page protection. But it's valid
3169 * for other architectures too.
3170 *
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003171 * Note that if FAULT_FLAG_WRITE is set, we either now have
Linus Torvalds1da177e2005-04-16 15:20:36 -07003172 * an exclusive copy of the page, or this is a shared mapping,
3173 * so we can make it writable and dirty to avoid having to
3174 * handle that later.
3175 */
3176 /* Only go through if we didn't race with anybody else... */
Andrea Arcangeli1c2fb7a2009-09-21 17:02:22 -07003177 if (likely(pte_same(*page_table, orig_pte))) {
Nick Piggind00806b2007-07-19 01:46:57 -07003178 flush_icache_page(vma, page);
3179 entry = mk_pte(page, vma->vm_page_prot);
Nick Piggin54cb8822007-07-19 01:46:59 -07003180 if (flags & FAULT_FLAG_WRITE)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003181 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003182 if (anon) {
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -08003183 inc_mm_counter_fast(mm, MM_ANONPAGES);
Lee Schermerhorn64d65192008-10-18 20:26:52 -07003184 page_add_new_anon_rmap(page, vma, address);
Hugh Dickinsf57e88a2005-11-21 21:32:19 -08003185 } else {
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -08003186 inc_mm_counter_fast(mm, MM_FILEPAGES);
Nick Piggind00806b2007-07-19 01:46:57 -07003187 page_add_file_rmap(page);
Nick Piggin54cb8822007-07-19 01:46:59 -07003188 if (flags & FAULT_FLAG_WRITE) {
Nick Piggind00806b2007-07-19 01:46:57 -07003189 dirty_page = page;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07003190 get_page(dirty_page);
3191 }
Hugh Dickins42946212005-10-29 18:16:05 -07003192 }
Lee Schermerhorn64d65192008-10-18 20:26:52 -07003193 set_pte_at(mm, address, page_table, entry);
Nick Piggind00806b2007-07-19 01:46:57 -07003194
3195 /* no need to invalidate: a not-present page won't be cached */
Russell King4b3073e2009-12-18 16:40:18 +00003196 update_mmu_cache(vma, address, page_table);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003197 } else {
KAMEZAWA Hiroyuki5b4e6552008-10-18 20:28:10 -07003198 if (charged)
3199 mem_cgroup_uncharge_page(page);
Nick Piggind00806b2007-07-19 01:46:57 -07003200 if (anon)
3201 page_cache_release(page);
3202 else
Nick Piggin54cb8822007-07-19 01:46:59 -07003203 anon = 1; /* no anon but release faulted_page */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003204 }
3205
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003206 pte_unmap_unlock(page_table, ptl);
Nick Piggind00806b2007-07-19 01:46:57 -07003207
3208out:
Nick Pigginb827e492009-04-30 15:08:16 -07003209 if (dirty_page) {
3210 struct address_space *mapping = page->mapping;
3211
3212 if (set_page_dirty(dirty_page))
3213 page_mkwrite = 1;
3214 unlock_page(dirty_page);
3215 put_page(dirty_page);
3216 if (page_mkwrite && mapping) {
3217 /*
3218 * Some device drivers do not set page.mapping but still
3219 * dirty their pages
3220 */
3221 balance_dirty_pages_ratelimited(mapping);
3222 }
3223
3224 /* file_update_time outside page_lock */
Anton Salikhmetov8f7b3d12008-01-23 02:21:18 +03003225 if (vma->vm_file)
3226 file_update_time(vma->vm_file);
Nick Pigginb827e492009-04-30 15:08:16 -07003227 } else {
3228 unlock_page(vmf.page);
3229 if (anon)
3230 page_cache_release(vmf.page);
Peter Zijlstrad08b3852006-09-25 23:30:57 -07003231 }
Nick Piggind00806b2007-07-19 01:46:57 -07003232
Nick Piggin83c54072007-07-19 01:47:05 -07003233 return ret;
Nick Pigginb827e492009-04-30 15:08:16 -07003234
3235unwritable_page:
3236 page_cache_release(page);
3237 return ret;
Nick Piggin54cb8822007-07-19 01:46:59 -07003238}
Nick Piggind00806b2007-07-19 01:46:57 -07003239
Nick Piggin54cb8822007-07-19 01:46:59 -07003240static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3241 unsigned long address, pte_t *page_table, pmd_t *pmd,
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003242 unsigned int flags, pte_t orig_pte)
Nick Piggin54cb8822007-07-19 01:46:59 -07003243{
3244 pgoff_t pgoff = (((address & PAGE_MASK)
Dean Nelson0da7e012007-10-16 01:24:45 -07003245 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
Nick Piggin54cb8822007-07-19 01:46:59 -07003246
Hugh Dickins16abfa02007-10-04 16:56:06 +01003247 pte_unmap(page_table);
3248 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
Nick Piggin54cb8822007-07-19 01:46:59 -07003249}
3250
Jes Sorensenf4b81802006-09-27 01:50:10 -07003251/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07003252 * Fault of a previously existing named mapping. Repopulate the pte
3253 * from the encoded file_pte if possible. This enables swappable
3254 * nonlinear vmas.
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003255 *
3256 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3257 * but allow concurrent faults), and pte mapped but not yet locked.
3258 * We return with mmap_sem still held, but pte unmapped and unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003259 */
Nick Piggind0217ac2007-07-19 01:47:03 -07003260static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
Hugh Dickins65500d22005-10-29 18:15:59 -07003261 unsigned long address, pte_t *page_table, pmd_t *pmd,
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003262 unsigned int flags, pte_t orig_pte)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003263{
Hugh Dickins65500d22005-10-29 18:15:59 -07003264 pgoff_t pgoff;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003265
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003266 flags |= FAULT_FLAG_NONLINEAR;
3267
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07003268 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
Nick Piggin83c54072007-07-19 01:47:05 -07003269 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003270
Hugh Dickins2509ef22009-01-06 14:40:10 -08003271 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
Hugh Dickins65500d22005-10-29 18:15:59 -07003272 /*
3273 * Page table corrupted: show pte and kill process.
3274 */
Hugh Dickins3dc14742009-01-06 14:40:08 -08003275 print_bad_pte(vma, address, orig_pte, NULL);
Hugh Dickinsd99be1a2009-12-14 17:59:04 -08003276 return VM_FAULT_SIGBUS;
Hugh Dickins65500d22005-10-29 18:15:59 -07003277 }
Hugh Dickins65500d22005-10-29 18:15:59 -07003278
3279 pgoff = pte_to_pgoff(orig_pte);
Hugh Dickins16abfa02007-10-04 16:56:06 +01003280 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003281}
3282
3283/*
3284 * These routines also need to handle stuff like marking pages dirty
3285 * and/or accessed for architectures that don't do it in hardware (most
3286 * RISC architectures). The early dirtying is also good on the i386.
3287 *
3288 * There is also a hook called "update_mmu_cache()" that architectures
3289 * with external mmu caches can use to update those (ie the Sparc or
3290 * PowerPC hashed page tables that act as extended TLBs).
3291 *
Hugh Dickinsc74df322005-10-29 18:16:23 -07003292 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3293 * but allow concurrent faults), and pte mapped but not yet locked.
3294 * We return with mmap_sem still held, but pte unmapped and unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003295 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08003296int handle_pte_fault(struct mm_struct *mm,
3297 struct vm_area_struct *vma, unsigned long address,
3298 pte_t *pte, pmd_t *pmd, unsigned int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003299{
3300 pte_t entry;
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003301 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003302
Benjamin Herrenschmidt8dab5242007-06-16 10:16:12 -07003303 entry = *pte;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003304 if (!pte_present(entry)) {
Hugh Dickins65500d22005-10-29 18:15:59 -07003305 if (pte_none(entry)) {
Jes Sorensenf4b81802006-09-27 01:50:10 -07003306 if (vma->vm_ops) {
Nick Piggin3c18ddd2008-04-28 02:12:10 -07003307 if (likely(vma->vm_ops->fault))
Nick Piggin54cb8822007-07-19 01:46:59 -07003308 return do_linear_fault(mm, vma, address,
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003309 pte, pmd, flags, entry);
Jes Sorensenf4b81802006-09-27 01:50:10 -07003310 }
3311 return do_anonymous_page(mm, vma, address,
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003312 pte, pmd, flags);
Hugh Dickins65500d22005-10-29 18:15:59 -07003313 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003314 if (pte_file(entry))
Nick Piggind0217ac2007-07-19 01:47:03 -07003315 return do_nonlinear_fault(mm, vma, address,
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003316 pte, pmd, flags, entry);
Hugh Dickins65500d22005-10-29 18:15:59 -07003317 return do_swap_page(mm, vma, address,
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003318 pte, pmd, flags, entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003319 }
3320
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07003321 ptl = pte_lockptr(mm, pmd);
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003322 spin_lock(ptl);
3323 if (unlikely(!pte_same(*pte, entry)))
3324 goto unlock;
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003325 if (flags & FAULT_FLAG_WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003326 if (!pte_write(entry))
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003327 return do_wp_page(mm, vma, address,
3328 pte, pmd, ptl, entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003329 entry = pte_mkdirty(entry);
3330 }
3331 entry = pte_mkyoung(entry);
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003332 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
Russell King4b3073e2009-12-18 16:40:18 +00003333 update_mmu_cache(vma, address, pte);
Andrea Arcangeli1a44e142005-10-29 18:16:48 -07003334 } else {
3335 /*
3336 * This is needed only for protection faults but the arch code
3337 * is not yet telling us if this is a protection fault or not.
3338 * This still avoids useless tlb flushes for .text page faults
3339 * with threads.
3340 */
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003341 if (flags & FAULT_FLAG_WRITE)
Shaohua Li61c77322010-08-16 09:16:55 +08003342 flush_tlb_fix_spurious_fault(vma, address);
Andrea Arcangeli1a44e142005-10-29 18:16:48 -07003343 }
Hugh Dickins8f4e2102005-10-29 18:16:26 -07003344unlock:
3345 pte_unmap_unlock(pte, ptl);
Nick Piggin83c54072007-07-19 01:47:05 -07003346 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003347}
3348
3349/*
3350 * By the time we get here, we already hold the mm semaphore
3351 */
Nick Piggin83c54072007-07-19 01:47:05 -07003352int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
Linus Torvaldsd06063c2009-04-10 09:01:23 -07003353 unsigned long address, unsigned int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003354{
3355 pgd_t *pgd;
3356 pud_t *pud;
3357 pmd_t *pmd;
3358 pte_t *pte;
3359
3360 __set_current_state(TASK_RUNNING);
3361
Christoph Lameterf8891e52006-06-30 01:55:45 -07003362 count_vm_event(PGFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003363
KAMEZAWA Hiroyuki34e55232010-03-05 13:41:40 -08003364 /* do counter updates before entering really critical section. */
3365 check_sync_rss_stat(current);
3366
Hugh Dickinsac9b9c62005-10-20 16:24:28 +01003367 if (unlikely(is_vm_hugetlb_page(vma)))
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003368 return hugetlb_fault(mm, vma, address, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003369
Linus Torvalds1da177e2005-04-16 15:20:36 -07003370 pgd = pgd_offset(mm, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003371 pud = pud_alloc(mm, pgd, address);
3372 if (!pud)
Hugh Dickinsc74df322005-10-29 18:16:23 -07003373 return VM_FAULT_OOM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003374 pmd = pmd_alloc(mm, pud, address);
3375 if (!pmd)
Hugh Dickinsc74df322005-10-29 18:16:23 -07003376 return VM_FAULT_OOM;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08003377 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3378 if (!vma->vm_ops)
3379 return do_huge_pmd_anonymous_page(mm, vma, address,
3380 pmd, flags);
3381 } else {
3382 pmd_t orig_pmd = *pmd;
3383 barrier();
3384 if (pmd_trans_huge(orig_pmd)) {
3385 if (flags & FAULT_FLAG_WRITE &&
3386 !pmd_write(orig_pmd) &&
3387 !pmd_trans_splitting(orig_pmd))
3388 return do_huge_pmd_wp_page(mm, vma, address,
3389 pmd, orig_pmd);
3390 return 0;
3391 }
3392 }
3393
3394 /*
3395 * Use __pte_alloc instead of pte_alloc_map, because we can't
3396 * run pte_offset_map on the pmd, if an huge pmd could
3397 * materialize from under us from a different thread.
3398 */
Mel Gormancc036382011-04-27 15:26:56 -07003399 if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address))
Hugh Dickinsc74df322005-10-29 18:16:23 -07003400 return VM_FAULT_OOM;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08003401 /* if an huge pmd materialized from under us just retry later */
3402 if (unlikely(pmd_trans_huge(*pmd)))
3403 return 0;
3404 /*
3405 * A regular pmd is established and it can't morph into a huge pmd
3406 * from under us anymore at this point because we hold the mmap_sem
3407 * read mode and khugepaged takes it in write mode. So now it's
3408 * safe to run pte_offset_map().
3409 */
3410 pte = pte_offset_map(pmd, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003411
Linus Torvalds30c9f3a2009-04-10 08:43:11 -07003412 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003413}
3414
3415#ifndef __PAGETABLE_PUD_FOLDED
3416/*
3417 * Allocate page upper directory.
Hugh Dickins872fec12005-10-29 18:16:21 -07003418 * We've already handled the fast-path in-line.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003419 */
Hugh Dickins1bb36302005-10-29 18:16:22 -07003420int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003421{
Hugh Dickinsc74df322005-10-29 18:16:23 -07003422 pud_t *new = pud_alloc_one(mm, address);
3423 if (!new)
Hugh Dickins1bb36302005-10-29 18:16:22 -07003424 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003425
Nick Piggin362a61a2008-05-14 06:37:36 +02003426 smp_wmb(); /* See comment in __pte_alloc */
3427
Hugh Dickins872fec12005-10-29 18:16:21 -07003428 spin_lock(&mm->page_table_lock);
Hugh Dickins1bb36302005-10-29 18:16:22 -07003429 if (pgd_present(*pgd)) /* Another has populated it */
Benjamin Herrenschmidt5e541972008-02-04 22:29:14 -08003430 pud_free(mm, new);
Hugh Dickins1bb36302005-10-29 18:16:22 -07003431 else
3432 pgd_populate(mm, pgd, new);
Hugh Dickinsc74df322005-10-29 18:16:23 -07003433 spin_unlock(&mm->page_table_lock);
Hugh Dickins1bb36302005-10-29 18:16:22 -07003434 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003435}
3436#endif /* __PAGETABLE_PUD_FOLDED */
3437
3438#ifndef __PAGETABLE_PMD_FOLDED
3439/*
3440 * Allocate page middle directory.
Hugh Dickins872fec12005-10-29 18:16:21 -07003441 * We've already handled the fast-path in-line.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003442 */
Hugh Dickins1bb36302005-10-29 18:16:22 -07003443int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003444{
Hugh Dickinsc74df322005-10-29 18:16:23 -07003445 pmd_t *new = pmd_alloc_one(mm, address);
3446 if (!new)
Hugh Dickins1bb36302005-10-29 18:16:22 -07003447 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003448
Nick Piggin362a61a2008-05-14 06:37:36 +02003449 smp_wmb(); /* See comment in __pte_alloc */
3450
Hugh Dickins872fec12005-10-29 18:16:21 -07003451 spin_lock(&mm->page_table_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003452#ifndef __ARCH_HAS_4LEVEL_HACK
Hugh Dickins1bb36302005-10-29 18:16:22 -07003453 if (pud_present(*pud)) /* Another has populated it */
Benjamin Herrenschmidt5e541972008-02-04 22:29:14 -08003454 pmd_free(mm, new);
Hugh Dickins1bb36302005-10-29 18:16:22 -07003455 else
3456 pud_populate(mm, pud, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003457#else
Hugh Dickins1bb36302005-10-29 18:16:22 -07003458 if (pgd_present(*pud)) /* Another has populated it */
Benjamin Herrenschmidt5e541972008-02-04 22:29:14 -08003459 pmd_free(mm, new);
Hugh Dickins1bb36302005-10-29 18:16:22 -07003460 else
3461 pgd_populate(mm, pud, new);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003462#endif /* __ARCH_HAS_4LEVEL_HACK */
Hugh Dickinsc74df322005-10-29 18:16:23 -07003463 spin_unlock(&mm->page_table_lock);
Hugh Dickins1bb36302005-10-29 18:16:22 -07003464 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003465}
3466#endif /* __PAGETABLE_PMD_FOLDED */
3467
3468int make_pages_present(unsigned long addr, unsigned long end)
3469{
3470 int ret, len, write;
3471 struct vm_area_struct * vma;
3472
3473 vma = find_vma(current->mm, addr);
3474 if (!vma)
KOSAKI Motohiroa4770972008-08-04 13:41:14 -07003475 return -ENOMEM;
Michel Lespinasse5ecfda02011-01-13 15:46:09 -08003476 /*
3477 * We want to touch writable mappings with a write fault in order
3478 * to break COW, except for shared mappings because these don't COW
3479 * and we would not want to dirty them for nothing.
3480 */
3481 write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
Eric Sesterhenn5bcb28b2006-03-26 18:30:52 +02003482 BUG_ON(addr >= end);
3483 BUG_ON(end > vma->vm_end);
Rolf Eike Beer68e116a2007-07-15 23:38:03 -07003484 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003485 ret = get_user_pages(current, current->mm, addr,
3486 len, write, 0, NULL, NULL);
Lee Schermerhornc11d69d2008-10-18 20:26:56 -07003487 if (ret < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003488 return ret;
Lee Schermerhorn9978ad52008-10-18 20:26:56 -07003489 return ret == len ? 0 : -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003490}
3491
Linus Torvalds1da177e2005-04-16 15:20:36 -07003492#if !defined(__HAVE_ARCH_GATE_AREA)
3493
3494#if defined(AT_SYSINFO_EHDR)
Adrian Bunk5ce78522005-09-10 00:26:28 -07003495static struct vm_area_struct gate_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003496
3497static int __init gate_vma_init(void)
3498{
3499 gate_vma.vm_mm = NULL;
3500 gate_vma.vm_start = FIXADDR_USER_START;
3501 gate_vma.vm_end = FIXADDR_USER_END;
Roland McGrathb6558c42007-01-26 00:56:47 -08003502 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
3503 gate_vma.vm_page_prot = __P101;
Roland McGrathf47aef52007-01-26 00:56:49 -08003504 /*
3505 * Make sure the vDSO gets into every core dump.
3506 * Dumping its contents makes post-mortem fully interpretable later
3507 * without matching up the same kernel and hardware config to see
3508 * what PC values meant.
3509 */
3510 gate_vma.vm_flags |= VM_ALWAYSDUMP;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003511 return 0;
3512}
3513__initcall(gate_vma_init);
3514#endif
3515
Stephen Wilson31db58b2011-03-13 15:49:15 -04003516struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003517{
3518#ifdef AT_SYSINFO_EHDR
3519 return &gate_vma;
3520#else
3521 return NULL;
3522#endif
3523}
3524
Stephen Wilsoncae5d392011-03-13 15:49:17 -04003525int in_gate_area_no_mm(unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003526{
3527#ifdef AT_SYSINFO_EHDR
3528 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
3529 return 1;
3530#endif
3531 return 0;
3532}
3533
3534#endif /* __HAVE_ARCH_GATE_AREA */
David Howells0ec76a12006-09-27 01:50:15 -07003535
Namhyung Kim1b36ba82010-10-26 14:22:00 -07003536static int __follow_pte(struct mm_struct *mm, unsigned long address,
Johannes Weinerf8ad0f492009-06-16 15:32:33 -07003537 pte_t **ptepp, spinlock_t **ptlp)
3538{
3539 pgd_t *pgd;
3540 pud_t *pud;
3541 pmd_t *pmd;
3542 pte_t *ptep;
3543
3544 pgd = pgd_offset(mm, address);
3545 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3546 goto out;
3547
3548 pud = pud_offset(pgd, address);
3549 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3550 goto out;
3551
3552 pmd = pmd_offset(pud, address);
Andrea Arcangelif66055a2011-01-13 15:46:54 -08003553 VM_BUG_ON(pmd_trans_huge(*pmd));
Johannes Weinerf8ad0f492009-06-16 15:32:33 -07003554 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
3555 goto out;
3556
3557 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
3558 if (pmd_huge(*pmd))
3559 goto out;
3560
3561 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
3562 if (!ptep)
3563 goto out;
3564 if (!pte_present(*ptep))
3565 goto unlock;
3566 *ptepp = ptep;
3567 return 0;
3568unlock:
3569 pte_unmap_unlock(ptep, *ptlp);
3570out:
3571 return -EINVAL;
3572}
3573
Namhyung Kim1b36ba82010-10-26 14:22:00 -07003574static inline int follow_pte(struct mm_struct *mm, unsigned long address,
3575 pte_t **ptepp, spinlock_t **ptlp)
3576{
3577 int res;
3578
3579 /* (void) is needed to make gcc happy */
3580 (void) __cond_lock(*ptlp,
3581 !(res = __follow_pte(mm, address, ptepp, ptlp)));
3582 return res;
3583}
3584
Johannes Weiner3b6748e2009-06-16 15:32:35 -07003585/**
3586 * follow_pfn - look up PFN at a user virtual address
3587 * @vma: memory mapping
3588 * @address: user virtual address
3589 * @pfn: location to store found PFN
3590 *
3591 * Only IO mappings and raw PFN mappings are allowed.
3592 *
3593 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3594 */
3595int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3596 unsigned long *pfn)
3597{
3598 int ret = -EINVAL;
3599 spinlock_t *ptl;
3600 pte_t *ptep;
3601
3602 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3603 return ret;
3604
3605 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3606 if (ret)
3607 return ret;
3608 *pfn = pte_pfn(*ptep);
3609 pte_unmap_unlock(ptep, ptl);
3610 return 0;
3611}
3612EXPORT_SYMBOL(follow_pfn);
3613
Rik van Riel28b2ee22008-07-23 21:27:05 -07003614#ifdef CONFIG_HAVE_IOREMAP_PROT
venkatesh.pallipadi@intel.comd87fe662008-12-19 13:47:27 -08003615int follow_phys(struct vm_area_struct *vma,
3616 unsigned long address, unsigned int flags,
3617 unsigned long *prot, resource_size_t *phys)
Rik van Riel28b2ee22008-07-23 21:27:05 -07003618{
Johannes Weiner03668a42009-06-16 15:32:34 -07003619 int ret = -EINVAL;
Rik van Riel28b2ee22008-07-23 21:27:05 -07003620 pte_t *ptep, pte;
3621 spinlock_t *ptl;
Rik van Riel28b2ee22008-07-23 21:27:05 -07003622
venkatesh.pallipadi@intel.comd87fe662008-12-19 13:47:27 -08003623 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3624 goto out;
Rik van Riel28b2ee22008-07-23 21:27:05 -07003625
Johannes Weiner03668a42009-06-16 15:32:34 -07003626 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
venkatesh.pallipadi@intel.comd87fe662008-12-19 13:47:27 -08003627 goto out;
Rik van Riel28b2ee22008-07-23 21:27:05 -07003628 pte = *ptep;
Johannes Weiner03668a42009-06-16 15:32:34 -07003629
Rik van Riel28b2ee22008-07-23 21:27:05 -07003630 if ((flags & FOLL_WRITE) && !pte_write(pte))
3631 goto unlock;
Rik van Riel28b2ee22008-07-23 21:27:05 -07003632
3633 *prot = pgprot_val(pte_pgprot(pte));
Johannes Weiner03668a42009-06-16 15:32:34 -07003634 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
Rik van Riel28b2ee22008-07-23 21:27:05 -07003635
Johannes Weiner03668a42009-06-16 15:32:34 -07003636 ret = 0;
Rik van Riel28b2ee22008-07-23 21:27:05 -07003637unlock:
3638 pte_unmap_unlock(ptep, ptl);
3639out:
venkatesh.pallipadi@intel.comd87fe662008-12-19 13:47:27 -08003640 return ret;
Rik van Riel28b2ee22008-07-23 21:27:05 -07003641}
3642
3643int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
3644 void *buf, int len, int write)
3645{
3646 resource_size_t phys_addr;
3647 unsigned long prot = 0;
KOSAKI Motohiro2bc72732009-01-06 14:39:43 -08003648 void __iomem *maddr;
Rik van Riel28b2ee22008-07-23 21:27:05 -07003649 int offset = addr & (PAGE_SIZE-1);
3650
venkatesh.pallipadi@intel.comd87fe662008-12-19 13:47:27 -08003651 if (follow_phys(vma, addr, write, &prot, &phys_addr))
Rik van Riel28b2ee22008-07-23 21:27:05 -07003652 return -EINVAL;
3653
3654 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
3655 if (write)
3656 memcpy_toio(maddr + offset, buf, len);
3657 else
3658 memcpy_fromio(buf, maddr + offset, len);
3659 iounmap(maddr);
3660
3661 return len;
3662}
3663#endif
3664
David Howells0ec76a12006-09-27 01:50:15 -07003665/*
Stephen Wilson206cb632011-03-13 15:49:19 -04003666 * Access another process' address space as given in mm. If non-NULL, use the
3667 * given task for page fault accounting.
David Howells0ec76a12006-09-27 01:50:15 -07003668 */
Stephen Wilson206cb632011-03-13 15:49:19 -04003669static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
3670 unsigned long addr, void *buf, int len, int write)
David Howells0ec76a12006-09-27 01:50:15 -07003671{
David Howells0ec76a12006-09-27 01:50:15 -07003672 struct vm_area_struct *vma;
David Howells0ec76a12006-09-27 01:50:15 -07003673 void *old_buf = buf;
3674
David Howells0ec76a12006-09-27 01:50:15 -07003675 down_read(&mm->mmap_sem);
Simon Arlott183ff222007-10-20 01:27:18 +02003676 /* ignore errors, just check how much was successfully transferred */
David Howells0ec76a12006-09-27 01:50:15 -07003677 while (len) {
3678 int bytes, ret, offset;
3679 void *maddr;
Rik van Riel28b2ee22008-07-23 21:27:05 -07003680 struct page *page = NULL;
David Howells0ec76a12006-09-27 01:50:15 -07003681
3682 ret = get_user_pages(tsk, mm, addr, 1,
3683 write, 1, &page, &vma);
Rik van Riel28b2ee22008-07-23 21:27:05 -07003684 if (ret <= 0) {
3685 /*
3686 * Check if this is a VM_IO | VM_PFNMAP VMA, which
3687 * we can access using slightly different code.
3688 */
3689#ifdef CONFIG_HAVE_IOREMAP_PROT
3690 vma = find_vma(mm, addr);
Michael Ellermanfe936df2011-04-14 15:22:10 -07003691 if (!vma || vma->vm_start > addr)
Rik van Riel28b2ee22008-07-23 21:27:05 -07003692 break;
3693 if (vma->vm_ops && vma->vm_ops->access)
3694 ret = vma->vm_ops->access(vma, addr, buf,
3695 len, write);
3696 if (ret <= 0)
3697#endif
3698 break;
3699 bytes = ret;
David Howells0ec76a12006-09-27 01:50:15 -07003700 } else {
Rik van Riel28b2ee22008-07-23 21:27:05 -07003701 bytes = len;
3702 offset = addr & (PAGE_SIZE-1);
3703 if (bytes > PAGE_SIZE-offset)
3704 bytes = PAGE_SIZE-offset;
3705
3706 maddr = kmap(page);
3707 if (write) {
3708 copy_to_user_page(vma, page, addr,
3709 maddr + offset, buf, bytes);
3710 set_page_dirty_lock(page);
3711 } else {
3712 copy_from_user_page(vma, page, addr,
3713 buf, maddr + offset, bytes);
3714 }
3715 kunmap(page);
3716 page_cache_release(page);
David Howells0ec76a12006-09-27 01:50:15 -07003717 }
David Howells0ec76a12006-09-27 01:50:15 -07003718 len -= bytes;
3719 buf += bytes;
3720 addr += bytes;
3721 }
3722 up_read(&mm->mmap_sem);
David Howells0ec76a12006-09-27 01:50:15 -07003723
3724 return buf - old_buf;
3725}
Andi Kleen03252912008-01-30 13:33:18 +01003726
Stephen Wilson5ddd36b2011-03-13 15:49:20 -04003727/**
Randy Dunlapae91dbf2011-03-26 13:27:01 -07003728 * access_remote_vm - access another process' address space
Stephen Wilson5ddd36b2011-03-13 15:49:20 -04003729 * @mm: the mm_struct of the target address space
3730 * @addr: start address to access
3731 * @buf: source or destination buffer
3732 * @len: number of bytes to transfer
3733 * @write: whether the access is a write
3734 *
3735 * The caller must hold a reference on @mm.
3736 */
3737int access_remote_vm(struct mm_struct *mm, unsigned long addr,
3738 void *buf, int len, int write)
3739{
3740 return __access_remote_vm(NULL, mm, addr, buf, len, write);
3741}
3742
Andi Kleen03252912008-01-30 13:33:18 +01003743/*
Stephen Wilson206cb632011-03-13 15:49:19 -04003744 * Access another process' address space.
3745 * Source/target buffer must be kernel space,
3746 * Do not walk the page table directly, use get_user_pages
3747 */
3748int access_process_vm(struct task_struct *tsk, unsigned long addr,
3749 void *buf, int len, int write)
3750{
3751 struct mm_struct *mm;
3752 int ret;
3753
3754 mm = get_task_mm(tsk);
3755 if (!mm)
3756 return 0;
3757
3758 ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
3759 mmput(mm);
3760
3761 return ret;
3762}
3763
Andi Kleen03252912008-01-30 13:33:18 +01003764/*
3765 * Print the name of a VMA.
3766 */
3767void print_vma_addr(char *prefix, unsigned long ip)
3768{
3769 struct mm_struct *mm = current->mm;
3770 struct vm_area_struct *vma;
3771
Ingo Molnare8bff742008-02-13 20:21:06 +01003772 /*
3773 * Do not print if we are in atomic
3774 * contexts (in exception stacks, etc.):
3775 */
3776 if (preempt_count())
3777 return;
3778
Andi Kleen03252912008-01-30 13:33:18 +01003779 down_read(&mm->mmap_sem);
3780 vma = find_vma(mm, ip);
3781 if (vma && vma->vm_file) {
3782 struct file *f = vma->vm_file;
3783 char *buf = (char *)__get_free_page(GFP_KERNEL);
3784 if (buf) {
3785 char *p, *s;
3786
Jan Blunckcf28b482008-02-14 19:38:44 -08003787 p = d_path(&f->f_path, buf, PAGE_SIZE);
Andi Kleen03252912008-01-30 13:33:18 +01003788 if (IS_ERR(p))
3789 p = "?";
3790 s = strrchr(p, '/');
3791 if (s)
3792 p = s+1;
3793 printk("%s%s[%lx+%lx]", prefix, p,
3794 vma->vm_start,
3795 vma->vm_end - vma->vm_start);
3796 free_page((unsigned long)buf);
3797 }
3798 }
3799 up_read(&current->mm->mmap_sem);
3800}
Nick Piggin3ee1afa2008-09-10 13:37:17 +02003801
3802#ifdef CONFIG_PROVE_LOCKING
3803void might_fault(void)
3804{
Peter Zijlstra95156f02009-01-12 13:02:11 +01003805 /*
3806 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
3807 * holding the mmap_sem, this is safe because kernel memory doesn't
3808 * get paged out, therefore we'll never actually fault, and the
3809 * below annotations will generate false positives.
3810 */
3811 if (segment_eq(get_fs(), KERNEL_DS))
3812 return;
3813
Nick Piggin3ee1afa2008-09-10 13:37:17 +02003814 might_sleep();
3815 /*
3816 * it would be nicer only to annotate paths which are not under
3817 * pagefault_disable, however that requires a larger audit and
3818 * providing helpers like get_user_atomic.
3819 */
3820 if (!in_atomic() && current->mm)
3821 might_lock_read(&current->mm->mmap_sem);
3822}
3823EXPORT_SYMBOL(might_fault);
3824#endif
Andrea Arcangeli47ad8472011-01-13 15:46:47 -08003825
3826#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
3827static void clear_gigantic_page(struct page *page,
3828 unsigned long addr,
3829 unsigned int pages_per_huge_page)
3830{
3831 int i;
3832 struct page *p = page;
3833
3834 might_sleep();
3835 for (i = 0; i < pages_per_huge_page;
3836 i++, p = mem_map_next(p, page, i)) {
3837 cond_resched();
3838 clear_user_highpage(p, addr + i * PAGE_SIZE);
3839 }
3840}
3841void clear_huge_page(struct page *page,
3842 unsigned long addr, unsigned int pages_per_huge_page)
3843{
3844 int i;
3845
3846 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3847 clear_gigantic_page(page, addr, pages_per_huge_page);
3848 return;
3849 }
3850
3851 might_sleep();
3852 for (i = 0; i < pages_per_huge_page; i++) {
3853 cond_resched();
3854 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
3855 }
3856}
3857
3858static void copy_user_gigantic_page(struct page *dst, struct page *src,
3859 unsigned long addr,
3860 struct vm_area_struct *vma,
3861 unsigned int pages_per_huge_page)
3862{
3863 int i;
3864 struct page *dst_base = dst;
3865 struct page *src_base = src;
3866
3867 for (i = 0; i < pages_per_huge_page; ) {
3868 cond_resched();
3869 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
3870
3871 i++;
3872 dst = mem_map_next(dst, dst_base, i);
3873 src = mem_map_next(src, src_base, i);
3874 }
3875}
3876
3877void copy_user_huge_page(struct page *dst, struct page *src,
3878 unsigned long addr, struct vm_area_struct *vma,
3879 unsigned int pages_per_huge_page)
3880{
3881 int i;
3882
3883 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
3884 copy_user_gigantic_page(dst, src, addr, vma,
3885 pages_per_huge_page);
3886 return;
3887 }
3888
3889 might_sleep();
3890 for (i = 0; i < pages_per_huge_page; i++) {
3891 cond_resched();
3892 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
3893 }
3894}
3895#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */