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Commit | Line | Data |
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c1a4de99 AA |
1 | /* |
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> | |
11 | #include <linux/pagemap.h> | |
12 | #include <linux/rmap.h> | |
13 | #include <linux/swap.h> | |
14 | #include <linux/swapops.h> | |
15 | #include <linux/userfaultfd_k.h> | |
16 | #include <linux/mmu_notifier.h> | |
60d4d2d2 MK |
17 | #include <linux/hugetlb.h> |
18 | #include <linux/pagemap.h> | |
26071ced | 19 | #include <linux/shmem_fs.h> |
c1a4de99 AA |
20 | #include <asm/tlbflush.h> |
21 | #include "internal.h" | |
22 | ||
23 | static int mcopy_atomic_pte(struct mm_struct *dst_mm, | |
24 | pmd_t *dst_pmd, | |
25 | struct vm_area_struct *dst_vma, | |
26 | unsigned long dst_addr, | |
b6ebaedb AA |
27 | unsigned long src_addr, |
28 | struct page **pagep) | |
c1a4de99 AA |
29 | { |
30 | struct mem_cgroup *memcg; | |
31 | pte_t _dst_pte, *dst_pte; | |
32 | spinlock_t *ptl; | |
c1a4de99 AA |
33 | void *page_kaddr; |
34 | int ret; | |
b6ebaedb | 35 | struct page *page; |
c1a4de99 | 36 | |
b6ebaedb AA |
37 | if (!*pagep) { |
38 | ret = -ENOMEM; | |
39 | page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); | |
40 | if (!page) | |
41 | goto out; | |
42 | ||
43 | page_kaddr = kmap_atomic(page); | |
44 | ret = copy_from_user(page_kaddr, | |
45 | (const void __user *) src_addr, | |
46 | PAGE_SIZE); | |
47 | kunmap_atomic(page_kaddr); | |
48 | ||
49 | /* fallback to copy_from_user outside mmap_sem */ | |
50 | if (unlikely(ret)) { | |
51 | ret = -EFAULT; | |
52 | *pagep = page; | |
53 | /* don't free the page */ | |
54 | goto out; | |
55 | } | |
56 | } else { | |
57 | page = *pagep; | |
58 | *pagep = NULL; | |
59 | } | |
c1a4de99 AA |
60 | |
61 | /* | |
62 | * The memory barrier inside __SetPageUptodate makes sure that | |
63 | * preceeding stores to the page contents become visible before | |
64 | * the set_pte_at() write. | |
65 | */ | |
66 | __SetPageUptodate(page); | |
67 | ||
68 | ret = -ENOMEM; | |
f627c2f5 | 69 | if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg, false)) |
c1a4de99 AA |
70 | goto out_release; |
71 | ||
72 | _dst_pte = mk_pte(page, dst_vma->vm_page_prot); | |
73 | if (dst_vma->vm_flags & VM_WRITE) | |
74 | _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte)); | |
75 | ||
76 | ret = -EEXIST; | |
77 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); | |
78 | if (!pte_none(*dst_pte)) | |
79 | goto out_release_uncharge_unlock; | |
80 | ||
81 | inc_mm_counter(dst_mm, MM_ANONPAGES); | |
d281ee61 | 82 | page_add_new_anon_rmap(page, dst_vma, dst_addr, false); |
f627c2f5 | 83 | mem_cgroup_commit_charge(page, memcg, false, false); |
c1a4de99 AA |
84 | lru_cache_add_active_or_unevictable(page, dst_vma); |
85 | ||
86 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); | |
87 | ||
88 | /* No need to invalidate - it was non-present before */ | |
89 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
90 | ||
91 | pte_unmap_unlock(dst_pte, ptl); | |
92 | ret = 0; | |
93 | out: | |
94 | return ret; | |
95 | out_release_uncharge_unlock: | |
96 | pte_unmap_unlock(dst_pte, ptl); | |
f627c2f5 | 97 | mem_cgroup_cancel_charge(page, memcg, false); |
c1a4de99 | 98 | out_release: |
09cbfeaf | 99 | put_page(page); |
c1a4de99 | 100 | goto out; |
c1a4de99 AA |
101 | } |
102 | ||
103 | static int mfill_zeropage_pte(struct mm_struct *dst_mm, | |
104 | pmd_t *dst_pmd, | |
105 | struct vm_area_struct *dst_vma, | |
106 | unsigned long dst_addr) | |
107 | { | |
108 | pte_t _dst_pte, *dst_pte; | |
109 | spinlock_t *ptl; | |
110 | int ret; | |
111 | ||
112 | _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), | |
113 | dst_vma->vm_page_prot)); | |
114 | ret = -EEXIST; | |
115 | dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); | |
116 | if (!pte_none(*dst_pte)) | |
117 | goto out_unlock; | |
118 | set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); | |
119 | /* No need to invalidate - it was non-present before */ | |
120 | update_mmu_cache(dst_vma, dst_addr, dst_pte); | |
121 | ret = 0; | |
122 | out_unlock: | |
123 | pte_unmap_unlock(dst_pte, ptl); | |
124 | return ret; | |
125 | } | |
126 | ||
127 | static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) | |
128 | { | |
129 | pgd_t *pgd; | |
130 | pud_t *pud; | |
131 | pmd_t *pmd = NULL; | |
132 | ||
133 | pgd = pgd_offset(mm, address); | |
134 | pud = pud_alloc(mm, pgd, address); | |
135 | if (pud) | |
136 | /* | |
137 | * Note that we didn't run this because the pmd was | |
138 | * missing, the *pmd may be already established and in | |
139 | * turn it may also be a trans_huge_pmd. | |
140 | */ | |
141 | pmd = pmd_alloc(mm, pud, address); | |
142 | return pmd; | |
143 | } | |
144 | ||
60d4d2d2 MK |
145 | #ifdef CONFIG_HUGETLB_PAGE |
146 | /* | |
147 | * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is | |
148 | * called with mmap_sem held, it will release mmap_sem before returning. | |
149 | */ | |
150 | static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, | |
151 | struct vm_area_struct *dst_vma, | |
152 | unsigned long dst_start, | |
153 | unsigned long src_start, | |
154 | unsigned long len, | |
155 | bool zeropage) | |
156 | { | |
1c9e8def MK |
157 | int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; |
158 | int vm_shared = dst_vma->vm_flags & VM_SHARED; | |
60d4d2d2 MK |
159 | ssize_t err; |
160 | pte_t *dst_pte; | |
161 | unsigned long src_addr, dst_addr; | |
162 | long copied; | |
163 | struct page *page; | |
164 | struct hstate *h; | |
165 | unsigned long vma_hpagesize; | |
166 | pgoff_t idx; | |
167 | u32 hash; | |
168 | struct address_space *mapping; | |
169 | ||
170 | /* | |
171 | * There is no default zero huge page for all huge page sizes as | |
172 | * supported by hugetlb. A PMD_SIZE huge pages may exist as used | |
173 | * by THP. Since we can not reliably insert a zero page, this | |
174 | * feature is not supported. | |
175 | */ | |
176 | if (zeropage) { | |
177 | up_read(&dst_mm->mmap_sem); | |
178 | return -EINVAL; | |
179 | } | |
180 | ||
181 | src_addr = src_start; | |
182 | dst_addr = dst_start; | |
183 | copied = 0; | |
184 | page = NULL; | |
185 | vma_hpagesize = vma_kernel_pagesize(dst_vma); | |
186 | ||
187 | /* | |
188 | * Validate alignment based on huge page size | |
189 | */ | |
190 | err = -EINVAL; | |
191 | if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) | |
192 | goto out_unlock; | |
193 | ||
194 | retry: | |
195 | /* | |
196 | * On routine entry dst_vma is set. If we had to drop mmap_sem and | |
197 | * retry, dst_vma will be set to NULL and we must lookup again. | |
198 | */ | |
199 | if (!dst_vma) { | |
27d02568 | 200 | err = -ENOENT; |
60d4d2d2 MK |
201 | dst_vma = find_vma(dst_mm, dst_start); |
202 | if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) | |
203 | goto out_unlock; | |
60d4d2d2 | 204 | /* |
27d02568 MR |
205 | * Only allow __mcopy_atomic_hugetlb on userfaultfd |
206 | * registered ranges. | |
60d4d2d2 | 207 | */ |
27d02568 MR |
208 | if (!dst_vma->vm_userfaultfd_ctx.ctx) |
209 | goto out_unlock; | |
210 | ||
60d4d2d2 MK |
211 | if (dst_start < dst_vma->vm_start || |
212 | dst_start + len > dst_vma->vm_end) | |
213 | goto out_unlock; | |
1c9e8def | 214 | |
27d02568 MR |
215 | err = -EINVAL; |
216 | if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) | |
217 | goto out_unlock; | |
218 | ||
1c9e8def | 219 | vm_shared = dst_vma->vm_flags & VM_SHARED; |
60d4d2d2 MK |
220 | } |
221 | ||
222 | if (WARN_ON(dst_addr & (vma_hpagesize - 1) || | |
223 | (len - copied) & (vma_hpagesize - 1))) | |
224 | goto out_unlock; | |
225 | ||
60d4d2d2 | 226 | /* |
1c9e8def | 227 | * If not shared, ensure the dst_vma has a anon_vma. |
60d4d2d2 MK |
228 | */ |
229 | err = -ENOMEM; | |
1c9e8def MK |
230 | if (!vm_shared) { |
231 | if (unlikely(anon_vma_prepare(dst_vma))) | |
232 | goto out_unlock; | |
233 | } | |
60d4d2d2 MK |
234 | |
235 | h = hstate_vma(dst_vma); | |
236 | ||
237 | while (src_addr < src_start + len) { | |
238 | pte_t dst_pteval; | |
239 | ||
240 | BUG_ON(dst_addr >= dst_start + len); | |
241 | VM_BUG_ON(dst_addr & ~huge_page_mask(h)); | |
242 | ||
243 | /* | |
244 | * Serialize via hugetlb_fault_mutex | |
245 | */ | |
246 | idx = linear_page_index(dst_vma, dst_addr); | |
247 | mapping = dst_vma->vm_file->f_mapping; | |
248 | hash = hugetlb_fault_mutex_hash(h, dst_mm, dst_vma, mapping, | |
249 | idx, dst_addr); | |
250 | mutex_lock(&hugetlb_fault_mutex_table[hash]); | |
251 | ||
252 | err = -ENOMEM; | |
253 | dst_pte = huge_pte_alloc(dst_mm, dst_addr, huge_page_size(h)); | |
254 | if (!dst_pte) { | |
255 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
256 | goto out_unlock; | |
257 | } | |
258 | ||
259 | err = -EEXIST; | |
260 | dst_pteval = huge_ptep_get(dst_pte); | |
261 | if (!huge_pte_none(dst_pteval)) { | |
262 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
263 | goto out_unlock; | |
264 | } | |
265 | ||
266 | err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, | |
267 | dst_addr, src_addr, &page); | |
268 | ||
269 | mutex_unlock(&hugetlb_fault_mutex_table[hash]); | |
1c9e8def | 270 | vm_alloc_shared = vm_shared; |
60d4d2d2 MK |
271 | |
272 | cond_resched(); | |
273 | ||
274 | if (unlikely(err == -EFAULT)) { | |
275 | up_read(&dst_mm->mmap_sem); | |
276 | BUG_ON(!page); | |
277 | ||
278 | err = copy_huge_page_from_user(page, | |
279 | (const void __user *)src_addr, | |
810a56b9 | 280 | pages_per_huge_page(h), true); |
60d4d2d2 MK |
281 | if (unlikely(err)) { |
282 | err = -EFAULT; | |
283 | goto out; | |
284 | } | |
285 | down_read(&dst_mm->mmap_sem); | |
286 | ||
287 | dst_vma = NULL; | |
288 | goto retry; | |
289 | } else | |
290 | BUG_ON(page); | |
291 | ||
292 | if (!err) { | |
293 | dst_addr += vma_hpagesize; | |
294 | src_addr += vma_hpagesize; | |
295 | copied += vma_hpagesize; | |
296 | ||
297 | if (fatal_signal_pending(current)) | |
298 | err = -EINTR; | |
299 | } | |
300 | if (err) | |
301 | break; | |
302 | } | |
303 | ||
304 | out_unlock: | |
305 | up_read(&dst_mm->mmap_sem); | |
306 | out: | |
21205bf8 MK |
307 | if (page) { |
308 | /* | |
309 | * We encountered an error and are about to free a newly | |
1c9e8def MK |
310 | * allocated huge page. |
311 | * | |
312 | * Reservation handling is very subtle, and is different for | |
313 | * private and shared mappings. See the routine | |
314 | * restore_reserve_on_error for details. Unfortunately, we | |
315 | * can not call restore_reserve_on_error now as it would | |
316 | * require holding mmap_sem. | |
317 | * | |
318 | * If a reservation for the page existed in the reservation | |
319 | * map of a private mapping, the map was modified to indicate | |
320 | * the reservation was consumed when the page was allocated. | |
321 | * We clear the PagePrivate flag now so that the global | |
21205bf8 MK |
322 | * reserve count will not be incremented in free_huge_page. |
323 | * The reservation map will still indicate the reservation | |
324 | * was consumed and possibly prevent later page allocation. | |
1c9e8def MK |
325 | * This is better than leaking a global reservation. If no |
326 | * reservation existed, it is still safe to clear PagePrivate | |
327 | * as no adjustments to reservation counts were made during | |
328 | * allocation. | |
329 | * | |
330 | * The reservation map for shared mappings indicates which | |
331 | * pages have reservations. When a huge page is allocated | |
332 | * for an address with a reservation, no change is made to | |
333 | * the reserve map. In this case PagePrivate will be set | |
334 | * to indicate that the global reservation count should be | |
335 | * incremented when the page is freed. This is the desired | |
336 | * behavior. However, when a huge page is allocated for an | |
337 | * address without a reservation a reservation entry is added | |
338 | * to the reservation map, and PagePrivate will not be set. | |
339 | * When the page is freed, the global reserve count will NOT | |
340 | * be incremented and it will appear as though we have leaked | |
341 | * reserved page. In this case, set PagePrivate so that the | |
342 | * global reserve count will be incremented to match the | |
343 | * reservation map entry which was created. | |
344 | * | |
345 | * Note that vm_alloc_shared is based on the flags of the vma | |
346 | * for which the page was originally allocated. dst_vma could | |
347 | * be different or NULL on error. | |
21205bf8 | 348 | */ |
1c9e8def MK |
349 | if (vm_alloc_shared) |
350 | SetPagePrivate(page); | |
351 | else | |
352 | ClearPagePrivate(page); | |
60d4d2d2 | 353 | put_page(page); |
21205bf8 | 354 | } |
60d4d2d2 MK |
355 | BUG_ON(copied < 0); |
356 | BUG_ON(err > 0); | |
357 | BUG_ON(!copied && !err); | |
358 | return copied ? copied : err; | |
359 | } | |
360 | #else /* !CONFIG_HUGETLB_PAGE */ | |
361 | /* fail at build time if gcc attempts to use this */ | |
362 | extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, | |
363 | struct vm_area_struct *dst_vma, | |
364 | unsigned long dst_start, | |
365 | unsigned long src_start, | |
366 | unsigned long len, | |
367 | bool zeropage); | |
368 | #endif /* CONFIG_HUGETLB_PAGE */ | |
369 | ||
c1a4de99 AA |
370 | static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, |
371 | unsigned long dst_start, | |
372 | unsigned long src_start, | |
373 | unsigned long len, | |
374 | bool zeropage) | |
375 | { | |
376 | struct vm_area_struct *dst_vma; | |
377 | ssize_t err; | |
378 | pmd_t *dst_pmd; | |
379 | unsigned long src_addr, dst_addr; | |
b6ebaedb AA |
380 | long copied; |
381 | struct page *page; | |
c1a4de99 AA |
382 | |
383 | /* | |
384 | * Sanitize the command parameters: | |
385 | */ | |
386 | BUG_ON(dst_start & ~PAGE_MASK); | |
387 | BUG_ON(len & ~PAGE_MASK); | |
388 | ||
389 | /* Does the address range wrap, or is the span zero-sized? */ | |
390 | BUG_ON(src_start + len <= src_start); | |
391 | BUG_ON(dst_start + len <= dst_start); | |
392 | ||
b6ebaedb AA |
393 | src_addr = src_start; |
394 | dst_addr = dst_start; | |
395 | copied = 0; | |
396 | page = NULL; | |
397 | retry: | |
c1a4de99 AA |
398 | down_read(&dst_mm->mmap_sem); |
399 | ||
400 | /* | |
401 | * Make sure the vma is not shared, that the dst range is | |
402 | * both valid and fully within a single existing vma. | |
403 | */ | |
27d02568 | 404 | err = -ENOENT; |
c1a4de99 | 405 | dst_vma = find_vma(dst_mm, dst_start); |
26071ced MR |
406 | if (!dst_vma) |
407 | goto out_unlock; | |
1c9e8def | 408 | /* |
27d02568 MR |
409 | * Be strict and only allow __mcopy_atomic on userfaultfd |
410 | * registered ranges to prevent userland errors going | |
411 | * unnoticed. As far as the VM consistency is concerned, it | |
412 | * would be perfectly safe to remove this check, but there's | |
413 | * no useful usage for __mcopy_atomic ouside of userfaultfd | |
414 | * registered ranges. This is after all why these are ioctls | |
415 | * belonging to the userfaultfd and not syscalls. | |
1c9e8def | 416 | */ |
27d02568 | 417 | if (!dst_vma->vm_userfaultfd_ctx.ctx) |
b6ebaedb | 418 | goto out_unlock; |
1c9e8def | 419 | |
c1a4de99 AA |
420 | if (dst_start < dst_vma->vm_start || |
421 | dst_start + len > dst_vma->vm_end) | |
b6ebaedb | 422 | goto out_unlock; |
c1a4de99 | 423 | |
27d02568 MR |
424 | err = -EINVAL; |
425 | /* | |
426 | * shmem_zero_setup is invoked in mmap for MAP_ANONYMOUS|MAP_SHARED but | |
427 | * it will overwrite vm_ops, so vma_is_anonymous must return false. | |
428 | */ | |
429 | if (WARN_ON_ONCE(vma_is_anonymous(dst_vma) && | |
430 | dst_vma->vm_flags & VM_SHARED)) | |
431 | goto out_unlock; | |
432 | ||
60d4d2d2 MK |
433 | /* |
434 | * If this is a HUGETLB vma, pass off to appropriate routine | |
435 | */ | |
436 | if (is_vm_hugetlb_page(dst_vma)) | |
437 | return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, | |
438 | src_start, len, zeropage); | |
439 | ||
26071ced | 440 | if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) |
b6ebaedb | 441 | goto out_unlock; |
c1a4de99 AA |
442 | |
443 | /* | |
444 | * Ensure the dst_vma has a anon_vma or this page | |
445 | * would get a NULL anon_vma when moved in the | |
446 | * dst_vma. | |
447 | */ | |
448 | err = -ENOMEM; | |
26071ced | 449 | if (vma_is_anonymous(dst_vma) && unlikely(anon_vma_prepare(dst_vma))) |
b6ebaedb | 450 | goto out_unlock; |
c1a4de99 | 451 | |
b6ebaedb | 452 | while (src_addr < src_start + len) { |
c1a4de99 | 453 | pmd_t dst_pmdval; |
b6ebaedb | 454 | |
c1a4de99 | 455 | BUG_ON(dst_addr >= dst_start + len); |
b6ebaedb | 456 | |
c1a4de99 AA |
457 | dst_pmd = mm_alloc_pmd(dst_mm, dst_addr); |
458 | if (unlikely(!dst_pmd)) { | |
459 | err = -ENOMEM; | |
460 | break; | |
461 | } | |
462 | ||
463 | dst_pmdval = pmd_read_atomic(dst_pmd); | |
464 | /* | |
465 | * If the dst_pmd is mapped as THP don't | |
466 | * override it and just be strict. | |
467 | */ | |
468 | if (unlikely(pmd_trans_huge(dst_pmdval))) { | |
469 | err = -EEXIST; | |
470 | break; | |
471 | } | |
472 | if (unlikely(pmd_none(dst_pmdval)) && | |
3ed3a4f0 | 473 | unlikely(__pte_alloc(dst_mm, dst_pmd, dst_addr))) { |
c1a4de99 AA |
474 | err = -ENOMEM; |
475 | break; | |
476 | } | |
477 | /* If an huge pmd materialized from under us fail */ | |
478 | if (unlikely(pmd_trans_huge(*dst_pmd))) { | |
479 | err = -EFAULT; | |
480 | break; | |
481 | } | |
482 | ||
483 | BUG_ON(pmd_none(*dst_pmd)); | |
484 | BUG_ON(pmd_trans_huge(*dst_pmd)); | |
485 | ||
26071ced MR |
486 | if (vma_is_anonymous(dst_vma)) { |
487 | if (!zeropage) | |
488 | err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, | |
489 | dst_addr, src_addr, | |
490 | &page); | |
491 | else | |
492 | err = mfill_zeropage_pte(dst_mm, dst_pmd, | |
493 | dst_vma, dst_addr); | |
494 | } else { | |
495 | err = -EINVAL; /* if zeropage is true return -EINVAL */ | |
496 | if (likely(!zeropage)) | |
497 | err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, | |
498 | dst_vma, dst_addr, | |
499 | src_addr, &page); | |
500 | } | |
c1a4de99 AA |
501 | |
502 | cond_resched(); | |
503 | ||
b6ebaedb AA |
504 | if (unlikely(err == -EFAULT)) { |
505 | void *page_kaddr; | |
506 | ||
507 | up_read(&dst_mm->mmap_sem); | |
508 | BUG_ON(!page); | |
509 | ||
510 | page_kaddr = kmap(page); | |
511 | err = copy_from_user(page_kaddr, | |
512 | (const void __user *) src_addr, | |
513 | PAGE_SIZE); | |
514 | kunmap(page); | |
515 | if (unlikely(err)) { | |
516 | err = -EFAULT; | |
517 | goto out; | |
518 | } | |
519 | goto retry; | |
520 | } else | |
521 | BUG_ON(page); | |
522 | ||
c1a4de99 AA |
523 | if (!err) { |
524 | dst_addr += PAGE_SIZE; | |
525 | src_addr += PAGE_SIZE; | |
526 | copied += PAGE_SIZE; | |
527 | ||
528 | if (fatal_signal_pending(current)) | |
529 | err = -EINTR; | |
530 | } | |
531 | if (err) | |
532 | break; | |
533 | } | |
534 | ||
b6ebaedb | 535 | out_unlock: |
c1a4de99 | 536 | up_read(&dst_mm->mmap_sem); |
b6ebaedb AA |
537 | out: |
538 | if (page) | |
09cbfeaf | 539 | put_page(page); |
c1a4de99 AA |
540 | BUG_ON(copied < 0); |
541 | BUG_ON(err > 0); | |
542 | BUG_ON(!copied && !err); | |
543 | return copied ? copied : err; | |
544 | } | |
545 | ||
546 | ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, | |
547 | unsigned long src_start, unsigned long len) | |
548 | { | |
549 | return __mcopy_atomic(dst_mm, dst_start, src_start, len, false); | |
550 | } | |
551 | ||
552 | ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, | |
553 | unsigned long len) | |
554 | { | |
555 | return __mcopy_atomic(dst_mm, start, 0, len, true); | |
556 | } |