blob: 8bcb501bce60b84f8bbc3c79cb2790bae2daa86a [file] [log] [blame]
Andrea Arcangelic1a4de92015-09-04 15:47:04 -07001/*
2 * mm/userfaultfd.c
3 *
4 * Copyright (C) 2015 Red Hat, Inc.
5 *
6 * This work is licensed under the terms of the GNU GPL, version 2. See
7 * the COPYING file in the top-level directory.
8 */
9
10#include <linux/mm.h>
Ingo Molnar174cd4b2017-02-02 19:15:33 +010011#include <linux/sched/signal.h>
Andrea Arcangelic1a4de92015-09-04 15:47:04 -070012#include <linux/pagemap.h>
13#include <linux/rmap.h>
14#include <linux/swap.h>
15#include <linux/swapops.h>
16#include <linux/userfaultfd_k.h>
17#include <linux/mmu_notifier.h>
Mike Kravetz60d4d2d2017-02-22 15:42:55 -080018#include <linux/hugetlb.h>
19#include <linux/pagemap.h>
Mike Rapoport26071ce2017-02-22 15:43:34 -080020#include <linux/shmem_fs.h>
Andrea Arcangelic1a4de92015-09-04 15:47:04 -070021#include <asm/tlbflush.h>
22#include "internal.h"
23
24static int mcopy_atomic_pte(struct mm_struct *dst_mm,
25 pmd_t *dst_pmd,
26 struct vm_area_struct *dst_vma,
27 unsigned long dst_addr,
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -070028 unsigned long src_addr,
29 struct page **pagep)
Andrea Arcangelic1a4de92015-09-04 15:47:04 -070030{
31 struct mem_cgroup *memcg;
32 pte_t _dst_pte, *dst_pte;
33 spinlock_t *ptl;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -070034 void *page_kaddr;
35 int ret;
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -070036 struct page *page;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -070037
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -070038 if (!*pagep) {
39 ret = -ENOMEM;
40 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr);
41 if (!page)
42 goto out;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -070043
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -070044 page_kaddr = kmap_atomic(page);
45 ret = copy_from_user(page_kaddr,
46 (const void __user *) src_addr,
47 PAGE_SIZE);
48 kunmap_atomic(page_kaddr);
49
50 /* fallback to copy_from_user outside mmap_sem */
51 if (unlikely(ret)) {
52 ret = -EFAULT;
53 *pagep = page;
54 /* don't free the page */
55 goto out;
56 }
57 } else {
58 page = *pagep;
59 *pagep = NULL;
60 }
Andrea Arcangelic1a4de92015-09-04 15:47:04 -070061
62 /*
63 * The memory barrier inside __SetPageUptodate makes sure that
64 * preceeding stores to the page contents become visible before
65 * the set_pte_at() write.
66 */
67 __SetPageUptodate(page);
68
69 ret = -ENOMEM;
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -080070 if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg, false))
Andrea Arcangelic1a4de92015-09-04 15:47:04 -070071 goto out_release;
72
73 _dst_pte = mk_pte(page, dst_vma->vm_page_prot);
74 if (dst_vma->vm_flags & VM_WRITE)
75 _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
76
77 ret = -EEXIST;
78 dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
79 if (!pte_none(*dst_pte))
80 goto out_release_uncharge_unlock;
81
82 inc_mm_counter(dst_mm, MM_ANONPAGES);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -080083 page_add_new_anon_rmap(page, dst_vma, dst_addr, false);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -080084 mem_cgroup_commit_charge(page, memcg, false, false);
Andrea Arcangelic1a4de92015-09-04 15:47:04 -070085 lru_cache_add_active_or_unevictable(page, dst_vma);
86
87 set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
88
89 /* No need to invalidate - it was non-present before */
90 update_mmu_cache(dst_vma, dst_addr, dst_pte);
91
92 pte_unmap_unlock(dst_pte, ptl);
93 ret = 0;
94out:
95 return ret;
96out_release_uncharge_unlock:
97 pte_unmap_unlock(dst_pte, ptl);
Kirill A. Shutemovf627c2f2016-01-15 16:52:20 -080098 mem_cgroup_cancel_charge(page, memcg, false);
Andrea Arcangelic1a4de92015-09-04 15:47:04 -070099out_release:
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300100 put_page(page);
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700101 goto out;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700102}
103
104static int mfill_zeropage_pte(struct mm_struct *dst_mm,
105 pmd_t *dst_pmd,
106 struct vm_area_struct *dst_vma,
107 unsigned long dst_addr)
108{
109 pte_t _dst_pte, *dst_pte;
110 spinlock_t *ptl;
111 int ret;
112
113 _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr),
114 dst_vma->vm_page_prot));
115 ret = -EEXIST;
116 dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
117 if (!pte_none(*dst_pte))
118 goto out_unlock;
119 set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
120 /* No need to invalidate - it was non-present before */
121 update_mmu_cache(dst_vma, dst_addr, dst_pte);
122 ret = 0;
123out_unlock:
124 pte_unmap_unlock(dst_pte, ptl);
125 return ret;
126}
127
128static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address)
129{
130 pgd_t *pgd;
Kirill A. Shutemovc2febaf2017-03-09 17:24:07 +0300131 p4d_t *p4d;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700132 pud_t *pud;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700133
134 pgd = pgd_offset(mm, address);
Kirill A. Shutemovc2febaf2017-03-09 17:24:07 +0300135 p4d = p4d_alloc(mm, pgd, address);
136 if (!p4d)
137 return NULL;
138 pud = pud_alloc(mm, p4d, address);
139 if (!pud)
140 return NULL;
141 /*
142 * Note that we didn't run this because the pmd was
143 * missing, the *pmd may be already established and in
144 * turn it may also be a trans_huge_pmd.
145 */
146 return pmd_alloc(mm, pud, address);
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700147}
148
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800149#ifdef CONFIG_HUGETLB_PAGE
150/*
151 * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is
152 * called with mmap_sem held, it will release mmap_sem before returning.
153 */
154static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
155 struct vm_area_struct *dst_vma,
156 unsigned long dst_start,
157 unsigned long src_start,
158 unsigned long len,
159 bool zeropage)
160{
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800161 int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED;
162 int vm_shared = dst_vma->vm_flags & VM_SHARED;
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800163 ssize_t err;
164 pte_t *dst_pte;
165 unsigned long src_addr, dst_addr;
166 long copied;
167 struct page *page;
168 struct hstate *h;
169 unsigned long vma_hpagesize;
170 pgoff_t idx;
171 u32 hash;
172 struct address_space *mapping;
173
174 /*
175 * There is no default zero huge page for all huge page sizes as
176 * supported by hugetlb. A PMD_SIZE huge pages may exist as used
177 * by THP. Since we can not reliably insert a zero page, this
178 * feature is not supported.
179 */
180 if (zeropage) {
181 up_read(&dst_mm->mmap_sem);
182 return -EINVAL;
183 }
184
185 src_addr = src_start;
186 dst_addr = dst_start;
187 copied = 0;
188 page = NULL;
189 vma_hpagesize = vma_kernel_pagesize(dst_vma);
190
191 /*
192 * Validate alignment based on huge page size
193 */
194 err = -EINVAL;
195 if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
196 goto out_unlock;
197
198retry:
199 /*
200 * On routine entry dst_vma is set. If we had to drop mmap_sem and
201 * retry, dst_vma will be set to NULL and we must lookup again.
202 */
203 if (!dst_vma) {
Mike Rapoport27d02562017-02-24 14:58:28 -0800204 err = -ENOENT;
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800205 dst_vma = find_vma(dst_mm, dst_start);
206 if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
207 goto out_unlock;
Mike Rapoport27d02562017-02-24 14:58:28 -0800208 /*
209 * Only allow __mcopy_atomic_hugetlb on userfaultfd
210 * registered ranges.
211 */
212 if (!dst_vma->vm_userfaultfd_ctx.ctx)
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800213 goto out_unlock;
214
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800215 if (dst_start < dst_vma->vm_start ||
216 dst_start + len > dst_vma->vm_end)
217 goto out_unlock;
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800218
Mike Rapoport27d02562017-02-24 14:58:28 -0800219 err = -EINVAL;
220 if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
221 goto out_unlock;
222
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800223 vm_shared = dst_vma->vm_flags & VM_SHARED;
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800224 }
225
226 if (WARN_ON(dst_addr & (vma_hpagesize - 1) ||
227 (len - copied) & (vma_hpagesize - 1)))
228 goto out_unlock;
229
230 /*
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800231 * If not shared, ensure the dst_vma has a anon_vma.
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800232 */
233 err = -ENOMEM;
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800234 if (!vm_shared) {
235 if (unlikely(anon_vma_prepare(dst_vma)))
236 goto out_unlock;
237 }
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800238
239 h = hstate_vma(dst_vma);
240
241 while (src_addr < src_start + len) {
242 pte_t dst_pteval;
243
244 BUG_ON(dst_addr >= dst_start + len);
245 VM_BUG_ON(dst_addr & ~huge_page_mask(h));
246
247 /*
248 * Serialize via hugetlb_fault_mutex
249 */
250 idx = linear_page_index(dst_vma, dst_addr);
251 mapping = dst_vma->vm_file->f_mapping;
252 hash = hugetlb_fault_mutex_hash(h, dst_mm, dst_vma, mapping,
253 idx, dst_addr);
254 mutex_lock(&hugetlb_fault_mutex_table[hash]);
255
256 err = -ENOMEM;
257 dst_pte = huge_pte_alloc(dst_mm, dst_addr, huge_page_size(h));
258 if (!dst_pte) {
259 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
260 goto out_unlock;
261 }
262
263 err = -EEXIST;
264 dst_pteval = huge_ptep_get(dst_pte);
265 if (!huge_pte_none(dst_pteval)) {
266 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
267 goto out_unlock;
268 }
269
270 err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma,
271 dst_addr, src_addr, &page);
272
273 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800274 vm_alloc_shared = vm_shared;
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800275
276 cond_resched();
277
278 if (unlikely(err == -EFAULT)) {
279 up_read(&dst_mm->mmap_sem);
280 BUG_ON(!page);
281
282 err = copy_huge_page_from_user(page,
283 (const void __user *)src_addr,
Mike Kravetz810a56b2017-02-22 15:42:58 -0800284 pages_per_huge_page(h), true);
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800285 if (unlikely(err)) {
286 err = -EFAULT;
287 goto out;
288 }
289 down_read(&dst_mm->mmap_sem);
290
291 dst_vma = NULL;
292 goto retry;
293 } else
294 BUG_ON(page);
295
296 if (!err) {
297 dst_addr += vma_hpagesize;
298 src_addr += vma_hpagesize;
299 copied += vma_hpagesize;
300
301 if (fatal_signal_pending(current))
302 err = -EINTR;
303 }
304 if (err)
305 break;
306 }
307
308out_unlock:
309 up_read(&dst_mm->mmap_sem);
310out:
Mike Kravetz21205bf2017-02-22 15:43:16 -0800311 if (page) {
312 /*
313 * We encountered an error and are about to free a newly
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800314 * allocated huge page.
315 *
316 * Reservation handling is very subtle, and is different for
317 * private and shared mappings. See the routine
318 * restore_reserve_on_error for details. Unfortunately, we
319 * can not call restore_reserve_on_error now as it would
320 * require holding mmap_sem.
321 *
322 * If a reservation for the page existed in the reservation
323 * map of a private mapping, the map was modified to indicate
324 * the reservation was consumed when the page was allocated.
325 * We clear the PagePrivate flag now so that the global
Mike Kravetz21205bf2017-02-22 15:43:16 -0800326 * reserve count will not be incremented in free_huge_page.
327 * The reservation map will still indicate the reservation
328 * was consumed and possibly prevent later page allocation.
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800329 * This is better than leaking a global reservation. If no
330 * reservation existed, it is still safe to clear PagePrivate
331 * as no adjustments to reservation counts were made during
332 * allocation.
333 *
334 * The reservation map for shared mappings indicates which
335 * pages have reservations. When a huge page is allocated
336 * for an address with a reservation, no change is made to
337 * the reserve map. In this case PagePrivate will be set
338 * to indicate that the global reservation count should be
339 * incremented when the page is freed. This is the desired
340 * behavior. However, when a huge page is allocated for an
341 * address without a reservation a reservation entry is added
342 * to the reservation map, and PagePrivate will not be set.
343 * When the page is freed, the global reserve count will NOT
344 * be incremented and it will appear as though we have leaked
345 * reserved page. In this case, set PagePrivate so that the
346 * global reserve count will be incremented to match the
347 * reservation map entry which was created.
348 *
349 * Note that vm_alloc_shared is based on the flags of the vma
350 * for which the page was originally allocated. dst_vma could
351 * be different or NULL on error.
Mike Kravetz21205bf2017-02-22 15:43:16 -0800352 */
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800353 if (vm_alloc_shared)
354 SetPagePrivate(page);
355 else
356 ClearPagePrivate(page);
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800357 put_page(page);
Mike Kravetz21205bf2017-02-22 15:43:16 -0800358 }
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800359 BUG_ON(copied < 0);
360 BUG_ON(err > 0);
361 BUG_ON(!copied && !err);
362 return copied ? copied : err;
363}
364#else /* !CONFIG_HUGETLB_PAGE */
365/* fail at build time if gcc attempts to use this */
366extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
367 struct vm_area_struct *dst_vma,
368 unsigned long dst_start,
369 unsigned long src_start,
370 unsigned long len,
371 bool zeropage);
372#endif /* CONFIG_HUGETLB_PAGE */
373
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700374static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
375 unsigned long dst_start,
376 unsigned long src_start,
377 unsigned long len,
378 bool zeropage)
379{
380 struct vm_area_struct *dst_vma;
381 ssize_t err;
382 pmd_t *dst_pmd;
383 unsigned long src_addr, dst_addr;
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700384 long copied;
385 struct page *page;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700386
387 /*
388 * Sanitize the command parameters:
389 */
390 BUG_ON(dst_start & ~PAGE_MASK);
391 BUG_ON(len & ~PAGE_MASK);
392
393 /* Does the address range wrap, or is the span zero-sized? */
394 BUG_ON(src_start + len <= src_start);
395 BUG_ON(dst_start + len <= dst_start);
396
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700397 src_addr = src_start;
398 dst_addr = dst_start;
399 copied = 0;
400 page = NULL;
401retry:
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700402 down_read(&dst_mm->mmap_sem);
403
404 /*
405 * Make sure the vma is not shared, that the dst range is
406 * both valid and fully within a single existing vma.
407 */
Mike Rapoport27d02562017-02-24 14:58:28 -0800408 err = -ENOENT;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700409 dst_vma = find_vma(dst_mm, dst_start);
Mike Rapoport26071ce2017-02-22 15:43:34 -0800410 if (!dst_vma)
411 goto out_unlock;
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800412 /*
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700413 * Be strict and only allow __mcopy_atomic on userfaultfd
414 * registered ranges to prevent userland errors going
415 * unnoticed. As far as the VM consistency is concerned, it
416 * would be perfectly safe to remove this check, but there's
417 * no useful usage for __mcopy_atomic ouside of userfaultfd
418 * registered ranges. This is after all why these are ioctls
419 * belonging to the userfaultfd and not syscalls.
420 */
421 if (!dst_vma->vm_userfaultfd_ctx.ctx)
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700422 goto out_unlock;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700423
Mike Rapoport27d02562017-02-24 14:58:28 -0800424 if (dst_start < dst_vma->vm_start ||
425 dst_start + len > dst_vma->vm_end)
426 goto out_unlock;
427
428 err = -EINVAL;
429 /*
430 * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but
431 * it will overwrite vm_ops, so vma_is_anonymous must return false.
432 */
433 if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) &&
434 dst_vma->vm_flags & VM_SHARED))
435 goto out_unlock;
436
437 /*
438 * If this is a HUGETLB vma, pass off to appropriate routine
439 */
440 if (is_vm_hugetlb_page(dst_vma))
441 return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
442 src_start, len, zeropage);
443
Mike Rapoport26071ce2017-02-22 15:43:34 -0800444 if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700445 goto out_unlock;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700446
447 /*
448 * Ensure the dst_vma has a anon_vma or this page
449 * would get a NULL anon_vma when moved in the
450 * dst_vma.
451 */
452 err = -ENOMEM;
Mike Rapoport26071ce2017-02-22 15:43:34 -0800453 if (vma_is_anonymous(dst_vma) && unlikely(anon_vma_prepare(dst_vma)))
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700454 goto out_unlock;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700455
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700456 while (src_addr < src_start + len) {
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700457 pmd_t dst_pmdval;
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700458
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700459 BUG_ON(dst_addr >= dst_start + len);
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700460
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700461 dst_pmd = mm_alloc_pmd(dst_mm, dst_addr);
462 if (unlikely(!dst_pmd)) {
463 err = -ENOMEM;
464 break;
465 }
466
467 dst_pmdval = pmd_read_atomic(dst_pmd);
468 /*
469 * If the dst_pmd is mapped as THP don't
470 * override it and just be strict.
471 */
472 if (unlikely(pmd_trans_huge(dst_pmdval))) {
473 err = -EEXIST;
474 break;
475 }
476 if (unlikely(pmd_none(dst_pmdval)) &&
Kirill A. Shutemov3ed3a4f2016-03-17 14:19:11 -0700477 unlikely(__pte_alloc(dst_mm, dst_pmd, dst_addr))) {
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700478 err = -ENOMEM;
479 break;
480 }
481 /* If an huge pmd materialized from under us fail */
482 if (unlikely(pmd_trans_huge(*dst_pmd))) {
483 err = -EFAULT;
484 break;
485 }
486
487 BUG_ON(pmd_none(*dst_pmd));
488 BUG_ON(pmd_trans_huge(*dst_pmd));
489
Mike Rapoport26071ce2017-02-22 15:43:34 -0800490 if (vma_is_anonymous(dst_vma)) {
491 if (!zeropage)
492 err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
493 dst_addr, src_addr,
494 &page);
495 else
496 err = mfill_zeropage_pte(dst_mm, dst_pmd,
497 dst_vma, dst_addr);
498 } else {
499 err = -EINVAL; /* if zeropage is true return -EINVAL */
500 if (likely(!zeropage))
501 err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd,
502 dst_vma, dst_addr,
503 src_addr, &page);
504 }
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700505
506 cond_resched();
507
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700508 if (unlikely(err == -EFAULT)) {
509 void *page_kaddr;
510
511 up_read(&dst_mm->mmap_sem);
512 BUG_ON(!page);
513
514 page_kaddr = kmap(page);
515 err = copy_from_user(page_kaddr,
516 (const void __user *) src_addr,
517 PAGE_SIZE);
518 kunmap(page);
519 if (unlikely(err)) {
520 err = -EFAULT;
521 goto out;
522 }
523 goto retry;
524 } else
525 BUG_ON(page);
526
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700527 if (!err) {
528 dst_addr += PAGE_SIZE;
529 src_addr += PAGE_SIZE;
530 copied += PAGE_SIZE;
531
532 if (fatal_signal_pending(current))
533 err = -EINTR;
534 }
535 if (err)
536 break;
537 }
538
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700539out_unlock:
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700540 up_read(&dst_mm->mmap_sem);
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700541out:
542 if (page)
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300543 put_page(page);
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700544 BUG_ON(copied < 0);
545 BUG_ON(err > 0);
546 BUG_ON(!copied && !err);
547 return copied ? copied : err;
548}
549
550ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
551 unsigned long src_start, unsigned long len)
552{
553 return __mcopy_atomic(dst_mm, dst_start, src_start, len, false);
554}
555
556ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
557 unsigned long len)
558{
559 return __mcopy_atomic(dst_mm, start, 0, len, true);
560}