blob: 479e631d43c2f609466b1dee97ca2d0314ae12ba [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;
131 pud_t *pud;
132 pmd_t *pmd = NULL;
133
134 pgd = pgd_offset(mm, address);
135 pud = pud_alloc(mm, pgd, address);
136 if (pud)
137 /*
138 * Note that we didn't run this because the pmd was
139 * missing, the *pmd may be already established and in
140 * turn it may also be a trans_huge_pmd.
141 */
142 pmd = pmd_alloc(mm, pud, address);
143 return pmd;
144}
145
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800146#ifdef CONFIG_HUGETLB_PAGE
147/*
148 * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is
149 * called with mmap_sem held, it will release mmap_sem before returning.
150 */
151static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
152 struct vm_area_struct *dst_vma,
153 unsigned long dst_start,
154 unsigned long src_start,
155 unsigned long len,
156 bool zeropage)
157{
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800158 int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED;
159 int vm_shared = dst_vma->vm_flags & VM_SHARED;
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800160 ssize_t err;
161 pte_t *dst_pte;
162 unsigned long src_addr, dst_addr;
163 long copied;
164 struct page *page;
165 struct hstate *h;
166 unsigned long vma_hpagesize;
167 pgoff_t idx;
168 u32 hash;
169 struct address_space *mapping;
170
171 /*
172 * There is no default zero huge page for all huge page sizes as
173 * supported by hugetlb. A PMD_SIZE huge pages may exist as used
174 * by THP. Since we can not reliably insert a zero page, this
175 * feature is not supported.
176 */
177 if (zeropage) {
178 up_read(&dst_mm->mmap_sem);
179 return -EINVAL;
180 }
181
182 src_addr = src_start;
183 dst_addr = dst_start;
184 copied = 0;
185 page = NULL;
186 vma_hpagesize = vma_kernel_pagesize(dst_vma);
187
188 /*
189 * Validate alignment based on huge page size
190 */
191 err = -EINVAL;
192 if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1))
193 goto out_unlock;
194
195retry:
196 /*
197 * On routine entry dst_vma is set. If we had to drop mmap_sem and
198 * retry, dst_vma will be set to NULL and we must lookup again.
199 */
200 if (!dst_vma) {
Mike Rapoport27d02562017-02-24 14:58:28 -0800201 err = -ENOENT;
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800202 dst_vma = find_vma(dst_mm, dst_start);
203 if (!dst_vma || !is_vm_hugetlb_page(dst_vma))
204 goto out_unlock;
Mike Rapoport27d02562017-02-24 14:58:28 -0800205 /*
206 * Only allow __mcopy_atomic_hugetlb on userfaultfd
207 * registered ranges.
208 */
209 if (!dst_vma->vm_userfaultfd_ctx.ctx)
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800210 goto out_unlock;
211
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800212 if (dst_start < dst_vma->vm_start ||
213 dst_start + len > dst_vma->vm_end)
214 goto out_unlock;
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800215
Mike Rapoport27d02562017-02-24 14:58:28 -0800216 err = -EINVAL;
217 if (vma_hpagesize != vma_kernel_pagesize(dst_vma))
218 goto out_unlock;
219
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800220 vm_shared = dst_vma->vm_flags & VM_SHARED;
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800221 }
222
223 if (WARN_ON(dst_addr & (vma_hpagesize - 1) ||
224 (len - copied) & (vma_hpagesize - 1)))
225 goto out_unlock;
226
227 /*
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800228 * If not shared, ensure the dst_vma has a anon_vma.
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800229 */
230 err = -ENOMEM;
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800231 if (!vm_shared) {
232 if (unlikely(anon_vma_prepare(dst_vma)))
233 goto out_unlock;
234 }
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800235
236 h = hstate_vma(dst_vma);
237
238 while (src_addr < src_start + len) {
239 pte_t dst_pteval;
240
241 BUG_ON(dst_addr >= dst_start + len);
242 VM_BUG_ON(dst_addr & ~huge_page_mask(h));
243
244 /*
245 * Serialize via hugetlb_fault_mutex
246 */
247 idx = linear_page_index(dst_vma, dst_addr);
248 mapping = dst_vma->vm_file->f_mapping;
249 hash = hugetlb_fault_mutex_hash(h, dst_mm, dst_vma, mapping,
250 idx, dst_addr);
251 mutex_lock(&hugetlb_fault_mutex_table[hash]);
252
253 err = -ENOMEM;
254 dst_pte = huge_pte_alloc(dst_mm, dst_addr, huge_page_size(h));
255 if (!dst_pte) {
256 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
257 goto out_unlock;
258 }
259
260 err = -EEXIST;
261 dst_pteval = huge_ptep_get(dst_pte);
262 if (!huge_pte_none(dst_pteval)) {
263 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
264 goto out_unlock;
265 }
266
267 err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma,
268 dst_addr, src_addr, &page);
269
270 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800271 vm_alloc_shared = vm_shared;
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800272
273 cond_resched();
274
275 if (unlikely(err == -EFAULT)) {
276 up_read(&dst_mm->mmap_sem);
277 BUG_ON(!page);
278
279 err = copy_huge_page_from_user(page,
280 (const void __user *)src_addr,
Mike Kravetz810a56b2017-02-22 15:42:58 -0800281 pages_per_huge_page(h), true);
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800282 if (unlikely(err)) {
283 err = -EFAULT;
284 goto out;
285 }
286 down_read(&dst_mm->mmap_sem);
287
288 dst_vma = NULL;
289 goto retry;
290 } else
291 BUG_ON(page);
292
293 if (!err) {
294 dst_addr += vma_hpagesize;
295 src_addr += vma_hpagesize;
296 copied += vma_hpagesize;
297
298 if (fatal_signal_pending(current))
299 err = -EINTR;
300 }
301 if (err)
302 break;
303 }
304
305out_unlock:
306 up_read(&dst_mm->mmap_sem);
307out:
Mike Kravetz21205bf2017-02-22 15:43:16 -0800308 if (page) {
309 /*
310 * We encountered an error and are about to free a newly
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800311 * allocated huge page.
312 *
313 * Reservation handling is very subtle, and is different for
314 * private and shared mappings. See the routine
315 * restore_reserve_on_error for details. Unfortunately, we
316 * can not call restore_reserve_on_error now as it would
317 * require holding mmap_sem.
318 *
319 * If a reservation for the page existed in the reservation
320 * map of a private mapping, the map was modified to indicate
321 * the reservation was consumed when the page was allocated.
322 * We clear the PagePrivate flag now so that the global
Mike Kravetz21205bf2017-02-22 15:43:16 -0800323 * reserve count will not be incremented in free_huge_page.
324 * The reservation map will still indicate the reservation
325 * was consumed and possibly prevent later page allocation.
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800326 * This is better than leaking a global reservation. If no
327 * reservation existed, it is still safe to clear PagePrivate
328 * as no adjustments to reservation counts were made during
329 * allocation.
330 *
331 * The reservation map for shared mappings indicates which
332 * pages have reservations. When a huge page is allocated
333 * for an address with a reservation, no change is made to
334 * the reserve map. In this case PagePrivate will be set
335 * to indicate that the global reservation count should be
336 * incremented when the page is freed. This is the desired
337 * behavior. However, when a huge page is allocated for an
338 * address without a reservation a reservation entry is added
339 * to the reservation map, and PagePrivate will not be set.
340 * When the page is freed, the global reserve count will NOT
341 * be incremented and it will appear as though we have leaked
342 * reserved page. In this case, set PagePrivate so that the
343 * global reserve count will be incremented to match the
344 * reservation map entry which was created.
345 *
346 * Note that vm_alloc_shared is based on the flags of the vma
347 * for which the page was originally allocated. dst_vma could
348 * be different or NULL on error.
Mike Kravetz21205bf2017-02-22 15:43:16 -0800349 */
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800350 if (vm_alloc_shared)
351 SetPagePrivate(page);
352 else
353 ClearPagePrivate(page);
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800354 put_page(page);
Mike Kravetz21205bf2017-02-22 15:43:16 -0800355 }
Mike Kravetz60d4d2d2017-02-22 15:42:55 -0800356 BUG_ON(copied < 0);
357 BUG_ON(err > 0);
358 BUG_ON(!copied && !err);
359 return copied ? copied : err;
360}
361#else /* !CONFIG_HUGETLB_PAGE */
362/* fail at build time if gcc attempts to use this */
363extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm,
364 struct vm_area_struct *dst_vma,
365 unsigned long dst_start,
366 unsigned long src_start,
367 unsigned long len,
368 bool zeropage);
369#endif /* CONFIG_HUGETLB_PAGE */
370
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700371static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm,
372 unsigned long dst_start,
373 unsigned long src_start,
374 unsigned long len,
375 bool zeropage)
376{
377 struct vm_area_struct *dst_vma;
378 ssize_t err;
379 pmd_t *dst_pmd;
380 unsigned long src_addr, dst_addr;
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700381 long copied;
382 struct page *page;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700383
384 /*
385 * Sanitize the command parameters:
386 */
387 BUG_ON(dst_start & ~PAGE_MASK);
388 BUG_ON(len & ~PAGE_MASK);
389
390 /* Does the address range wrap, or is the span zero-sized? */
391 BUG_ON(src_start + len <= src_start);
392 BUG_ON(dst_start + len <= dst_start);
393
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700394 src_addr = src_start;
395 dst_addr = dst_start;
396 copied = 0;
397 page = NULL;
398retry:
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700399 down_read(&dst_mm->mmap_sem);
400
401 /*
402 * Make sure the vma is not shared, that the dst range is
403 * both valid and fully within a single existing vma.
404 */
Mike Rapoport27d02562017-02-24 14:58:28 -0800405 err = -ENOENT;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700406 dst_vma = find_vma(dst_mm, dst_start);
Mike Rapoport26071ce2017-02-22 15:43:34 -0800407 if (!dst_vma)
408 goto out_unlock;
Mike Kravetz1c9e8de2017-02-22 15:43:43 -0800409 /*
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700410 * Be strict and only allow __mcopy_atomic on userfaultfd
411 * registered ranges to prevent userland errors going
412 * unnoticed. As far as the VM consistency is concerned, it
413 * would be perfectly safe to remove this check, but there's
414 * no useful usage for __mcopy_atomic ouside of userfaultfd
415 * registered ranges. This is after all why these are ioctls
416 * belonging to the userfaultfd and not syscalls.
417 */
418 if (!dst_vma->vm_userfaultfd_ctx.ctx)
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700419 goto out_unlock;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700420
Mike Rapoport27d02562017-02-24 14:58:28 -0800421 if (dst_start < dst_vma->vm_start ||
422 dst_start + len > dst_vma->vm_end)
423 goto out_unlock;
424
425 err = -EINVAL;
426 /*
427 * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but
428 * it will overwrite vm_ops, so vma_is_anonymous must return false.
429 */
430 if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) &&
431 dst_vma->vm_flags & VM_SHARED))
432 goto out_unlock;
433
434 /*
435 * If this is a HUGETLB vma, pass off to appropriate routine
436 */
437 if (is_vm_hugetlb_page(dst_vma))
438 return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start,
439 src_start, len, zeropage);
440
Mike Rapoport26071ce2017-02-22 15:43:34 -0800441 if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma))
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700442 goto out_unlock;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700443
444 /*
445 * Ensure the dst_vma has a anon_vma or this page
446 * would get a NULL anon_vma when moved in the
447 * dst_vma.
448 */
449 err = -ENOMEM;
Mike Rapoport26071ce2017-02-22 15:43:34 -0800450 if (vma_is_anonymous(dst_vma) && unlikely(anon_vma_prepare(dst_vma)))
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700451 goto out_unlock;
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700452
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700453 while (src_addr < src_start + len) {
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700454 pmd_t dst_pmdval;
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700455
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700456 BUG_ON(dst_addr >= dst_start + len);
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700457
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700458 dst_pmd = mm_alloc_pmd(dst_mm, dst_addr);
459 if (unlikely(!dst_pmd)) {
460 err = -ENOMEM;
461 break;
462 }
463
464 dst_pmdval = pmd_read_atomic(dst_pmd);
465 /*
466 * If the dst_pmd is mapped as THP don't
467 * override it and just be strict.
468 */
469 if (unlikely(pmd_trans_huge(dst_pmdval))) {
470 err = -EEXIST;
471 break;
472 }
473 if (unlikely(pmd_none(dst_pmdval)) &&
Kirill A. Shutemov3ed3a4f2016-03-17 14:19:11 -0700474 unlikely(__pte_alloc(dst_mm, dst_pmd, dst_addr))) {
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700475 err = -ENOMEM;
476 break;
477 }
478 /* If an huge pmd materialized from under us fail */
479 if (unlikely(pmd_trans_huge(*dst_pmd))) {
480 err = -EFAULT;
481 break;
482 }
483
484 BUG_ON(pmd_none(*dst_pmd));
485 BUG_ON(pmd_trans_huge(*dst_pmd));
486
Mike Rapoport26071ce2017-02-22 15:43:34 -0800487 if (vma_is_anonymous(dst_vma)) {
488 if (!zeropage)
489 err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
490 dst_addr, src_addr,
491 &page);
492 else
493 err = mfill_zeropage_pte(dst_mm, dst_pmd,
494 dst_vma, dst_addr);
495 } else {
496 err = -EINVAL; /* if zeropage is true return -EINVAL */
497 if (likely(!zeropage))
498 err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd,
499 dst_vma, dst_addr,
500 src_addr, &page);
501 }
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700502
503 cond_resched();
504
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700505 if (unlikely(err == -EFAULT)) {
506 void *page_kaddr;
507
508 up_read(&dst_mm->mmap_sem);
509 BUG_ON(!page);
510
511 page_kaddr = kmap(page);
512 err = copy_from_user(page_kaddr,
513 (const void __user *) src_addr,
514 PAGE_SIZE);
515 kunmap(page);
516 if (unlikely(err)) {
517 err = -EFAULT;
518 goto out;
519 }
520 goto retry;
521 } else
522 BUG_ON(page);
523
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700524 if (!err) {
525 dst_addr += PAGE_SIZE;
526 src_addr += PAGE_SIZE;
527 copied += PAGE_SIZE;
528
529 if (fatal_signal_pending(current))
530 err = -EINTR;
531 }
532 if (err)
533 break;
534 }
535
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700536out_unlock:
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700537 up_read(&dst_mm->mmap_sem);
Andrea Arcangelib6ebaed2015-09-04 15:47:08 -0700538out:
539 if (page)
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300540 put_page(page);
Andrea Arcangelic1a4de92015-09-04 15:47:04 -0700541 BUG_ON(copied < 0);
542 BUG_ON(err > 0);
543 BUG_ON(!copied && !err);
544 return copied ? copied : err;
545}
546
547ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
548 unsigned long src_start, unsigned long len)
549{
550 return __mcopy_atomic(dst_mm, dst_start, src_start, len, false);
551}
552
553ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start,
554 unsigned long len)
555{
556 return __mcopy_atomic(dst_mm, start, 0, len, true);
557}