4 * (C) Copyright 1995 Linus Torvalds
5 * (C) Copyright 2002 Christoph Hellwig
8 #include <linux/capability.h>
9 #include <linux/mman.h>
11 #include <linux/swap.h>
12 #include <linux/swapops.h>
13 #include <linux/pagemap.h>
14 #include <linux/pagevec.h>
15 #include <linux/mempolicy.h>
16 #include <linux/syscalls.h>
17 #include <linux/sched.h>
18 #include <linux/export.h>
19 #include <linux/rmap.h>
20 #include <linux/mmzone.h>
21 #include <linux/hugetlb.h>
22 #include <linux/memcontrol.h>
23 #include <linux/mm_inline.h>
27 int can_do_mlock(void)
29 if (capable(CAP_IPC_LOCK
))
31 if (rlimit(RLIMIT_MEMLOCK
) != 0)
35 EXPORT_SYMBOL(can_do_mlock
);
38 * Mlocked pages are marked with PageMlocked() flag for efficient testing
39 * in vmscan and, possibly, the fault path; and to support semi-accurate
42 * An mlocked page [PageMlocked(page)] is unevictable. As such, it will
43 * be placed on the LRU "unevictable" list, rather than the [in]active lists.
44 * The unevictable list is an LRU sibling list to the [in]active lists.
45 * PageUnevictable is set to indicate the unevictable state.
47 * When lazy mlocking via vmscan, it is important to ensure that the
48 * vma's VM_LOCKED status is not concurrently being modified, otherwise we
49 * may have mlocked a page that is being munlocked. So lazy mlock must take
50 * the mmap_sem for read, and verify that the vma really is locked
55 * LRU accounting for clear_page_mlock()
57 void clear_page_mlock(struct page
*page
)
59 if (!TestClearPageMlocked(page
))
62 mod_zone_page_state(page_zone(page
), NR_MLOCK
,
63 -hpage_nr_pages(page
));
64 count_vm_event(UNEVICTABLE_PGCLEARED
);
65 if (!isolate_lru_page(page
)) {
66 putback_lru_page(page
);
69 * We lost the race. the page already moved to evictable list.
71 if (PageUnevictable(page
))
72 count_vm_event(UNEVICTABLE_PGSTRANDED
);
77 * Mark page as mlocked if not already.
78 * If page on LRU, isolate and putback to move to unevictable list.
80 void mlock_vma_page(struct page
*page
)
82 BUG_ON(!PageLocked(page
));
84 if (!TestSetPageMlocked(page
)) {
85 mod_zone_page_state(page_zone(page
), NR_MLOCK
,
86 hpage_nr_pages(page
));
87 count_vm_event(UNEVICTABLE_PGMLOCKED
);
88 if (!isolate_lru_page(page
))
89 putback_lru_page(page
);
94 * Isolate a page from LRU with optional get_page() pin.
95 * Assumes lru_lock already held and page already pinned.
97 static bool __munlock_isolate_lru_page(struct page
*page
, bool getpage
)
100 struct lruvec
*lruvec
;
102 lruvec
= mem_cgroup_page_lruvec(page
, page_zone(page
));
106 del_page_from_lru_list(page
, lruvec
, page_lru(page
));
114 * Finish munlock after successful page isolation
116 * Page must be locked. This is a wrapper for try_to_munlock()
117 * and putback_lru_page() with munlock accounting.
119 static void __munlock_isolated_page(struct page
*page
)
121 int ret
= SWAP_AGAIN
;
124 * Optimization: if the page was mapped just once, that's our mapping
125 * and we don't need to check all the other vmas.
127 if (page_mapcount(page
) > 1)
128 ret
= try_to_munlock(page
);
130 /* Did try_to_unlock() succeed or punt? */
131 if (ret
!= SWAP_MLOCK
)
132 count_vm_event(UNEVICTABLE_PGMUNLOCKED
);
134 putback_lru_page(page
);
138 * Accounting for page isolation fail during munlock
140 * Performs accounting when page isolation fails in munlock. There is nothing
141 * else to do because it means some other task has already removed the page
142 * from the LRU. putback_lru_page() will take care of removing the page from
143 * the unevictable list, if necessary. vmscan [page_referenced()] will move
144 * the page back to the unevictable list if some other vma has it mlocked.
146 static void __munlock_isolation_failed(struct page
*page
)
148 if (PageUnevictable(page
))
149 __count_vm_event(UNEVICTABLE_PGSTRANDED
);
151 __count_vm_event(UNEVICTABLE_PGMUNLOCKED
);
155 * munlock_vma_page - munlock a vma page
156 * @page - page to be unlocked, either a normal page or THP page head
158 * returns the size of the page as a page mask (0 for normal page,
159 * HPAGE_PMD_NR - 1 for THP head page)
161 * called from munlock()/munmap() path with page supposedly on the LRU.
162 * When we munlock a page, because the vma where we found the page is being
163 * munlock()ed or munmap()ed, we want to check whether other vmas hold the
164 * page locked so that we can leave it on the unevictable lru list and not
165 * bother vmscan with it. However, to walk the page's rmap list in
166 * try_to_munlock() we must isolate the page from the LRU. If some other
167 * task has removed the page from the LRU, we won't be able to do that.
168 * So we clear the PageMlocked as we might not get another chance. If we
169 * can't isolate the page, we leave it for putback_lru_page() and vmscan
170 * [page_referenced()/try_to_unmap()] to deal with.
172 unsigned int munlock_vma_page(struct page
*page
)
174 unsigned int nr_pages
;
175 struct zone
*zone
= page_zone(page
);
177 BUG_ON(!PageLocked(page
));
180 * Serialize with any parallel __split_huge_page_refcount() which
181 * might otherwise copy PageMlocked to part of the tail pages before
182 * we clear it in the head page. It also stabilizes hpage_nr_pages().
184 spin_lock_irq(&zone
->lru_lock
);
186 nr_pages
= hpage_nr_pages(page
);
187 if (!TestClearPageMlocked(page
))
190 __mod_zone_page_state(zone
, NR_MLOCK
, -nr_pages
);
192 if (__munlock_isolate_lru_page(page
, true)) {
193 spin_unlock_irq(&zone
->lru_lock
);
194 __munlock_isolated_page(page
);
197 __munlock_isolation_failed(page
);
200 spin_unlock_irq(&zone
->lru_lock
);
207 * __mlock_vma_pages_range() - mlock a range of pages in the vma.
209 * @start: start address
212 * This takes care of making the pages present too.
214 * return 0 on success, negative error code on error.
216 * vma->vm_mm->mmap_sem must be held for at least read.
218 long __mlock_vma_pages_range(struct vm_area_struct
*vma
,
219 unsigned long start
, unsigned long end
, int *nonblocking
)
221 struct mm_struct
*mm
= vma
->vm_mm
;
222 unsigned long nr_pages
= (end
- start
) / PAGE_SIZE
;
225 VM_BUG_ON(start
& ~PAGE_MASK
);
226 VM_BUG_ON(end
& ~PAGE_MASK
);
227 VM_BUG_ON(start
< vma
->vm_start
);
228 VM_BUG_ON(end
> vma
->vm_end
);
229 VM_BUG_ON(!rwsem_is_locked(&mm
->mmap_sem
));
231 gup_flags
= FOLL_TOUCH
| FOLL_MLOCK
;
233 * We want to touch writable mappings with a write fault in order
234 * to break COW, except for shared mappings because these don't COW
235 * and we would not want to dirty them for nothing.
237 if ((vma
->vm_flags
& (VM_WRITE
| VM_SHARED
)) == VM_WRITE
)
238 gup_flags
|= FOLL_WRITE
;
241 * We want mlock to succeed for regions that have any permissions
242 * other than PROT_NONE.
244 if (vma
->vm_flags
& (VM_READ
| VM_WRITE
| VM_EXEC
))
245 gup_flags
|= FOLL_FORCE
;
248 * We made sure addr is within a VMA, so the following will
249 * not result in a stack expansion that recurses back here.
251 return __get_user_pages(current
, mm
, start
, nr_pages
, gup_flags
,
252 NULL
, NULL
, nonblocking
);
256 * convert get_user_pages() return value to posix mlock() error
258 static int __mlock_posix_error_return(long retval
)
260 if (retval
== -EFAULT
)
262 else if (retval
== -ENOMEM
)
268 * Prepare page for fast batched LRU putback via putback_lru_evictable_pagevec()
270 * The fast path is available only for evictable pages with single mapping.
271 * Then we can bypass the per-cpu pvec and get better performance.
272 * when mapcount > 1 we need try_to_munlock() which can fail.
273 * when !page_evictable(), we need the full redo logic of putback_lru_page to
274 * avoid leaving evictable page in unevictable list.
276 * In case of success, @page is added to @pvec and @pgrescued is incremented
277 * in case that the page was previously unevictable. @page is also unlocked.
279 static bool __putback_lru_fast_prepare(struct page
*page
, struct pagevec
*pvec
,
282 VM_BUG_ON_PAGE(PageLRU(page
), page
);
283 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
285 if (page_mapcount(page
) <= 1 && page_evictable(page
)) {
286 pagevec_add(pvec
, page
);
287 if (TestClearPageUnevictable(page
))
297 * Putback multiple evictable pages to the LRU
299 * Batched putback of evictable pages that bypasses the per-cpu pvec. Some of
300 * the pages might have meanwhile become unevictable but that is OK.
302 static void __putback_lru_fast(struct pagevec
*pvec
, int pgrescued
)
304 count_vm_events(UNEVICTABLE_PGMUNLOCKED
, pagevec_count(pvec
));
306 *__pagevec_lru_add() calls release_pages() so we don't call
307 * put_page() explicitly
309 __pagevec_lru_add(pvec
);
310 count_vm_events(UNEVICTABLE_PGRESCUED
, pgrescued
);
314 * Munlock a batch of pages from the same zone
316 * The work is split to two main phases. First phase clears the Mlocked flag
317 * and attempts to isolate the pages, all under a single zone lru lock.
318 * The second phase finishes the munlock only for pages where isolation
321 * Note that the pagevec may be modified during the process.
323 static void __munlock_pagevec(struct pagevec
*pvec
, struct zone
*zone
)
326 int nr
= pagevec_count(pvec
);
328 struct pagevec pvec_putback
;
331 pagevec_init(&pvec_putback
, 0);
333 /* Phase 1: page isolation */
334 spin_lock_irq(&zone
->lru_lock
);
335 for (i
= 0; i
< nr
; i
++) {
336 struct page
*page
= pvec
->pages
[i
];
338 if (TestClearPageMlocked(page
)) {
340 * We already have pin from follow_page_mask()
341 * so we can spare the get_page() here.
343 if (__munlock_isolate_lru_page(page
, false))
346 __munlock_isolation_failed(page
);
350 * We won't be munlocking this page in the next phase
351 * but we still need to release the follow_page_mask()
352 * pin. We cannot do it under lru_lock however. If it's
353 * the last pin, __page_cache_release() would deadlock.
355 pagevec_add(&pvec_putback
, pvec
->pages
[i
]);
356 pvec
->pages
[i
] = NULL
;
358 delta_munlocked
= -nr
+ pagevec_count(&pvec_putback
);
359 __mod_zone_page_state(zone
, NR_MLOCK
, delta_munlocked
);
360 spin_unlock_irq(&zone
->lru_lock
);
362 /* Now we can release pins of pages that we are not munlocking */
363 pagevec_release(&pvec_putback
);
365 /* Phase 2: page munlock */
366 for (i
= 0; i
< nr
; i
++) {
367 struct page
*page
= pvec
->pages
[i
];
371 if (!__putback_lru_fast_prepare(page
, &pvec_putback
,
374 * Slow path. We don't want to lose the last
375 * pin before unlock_page()
377 get_page(page
); /* for putback_lru_page() */
378 __munlock_isolated_page(page
);
380 put_page(page
); /* from follow_page_mask() */
386 * Phase 3: page putback for pages that qualified for the fast path
387 * This will also call put_page() to return pin from follow_page_mask()
389 if (pagevec_count(&pvec_putback
))
390 __putback_lru_fast(&pvec_putback
, pgrescued
);
394 * Fill up pagevec for __munlock_pagevec using pte walk
396 * The function expects that the struct page corresponding to @start address is
397 * a non-TPH page already pinned and in the @pvec, and that it belongs to @zone.
399 * The rest of @pvec is filled by subsequent pages within the same pmd and same
400 * zone, as long as the pte's are present and vm_normal_page() succeeds. These
401 * pages also get pinned.
403 * Returns the address of the next page that should be scanned. This equals
404 * @start + PAGE_SIZE when no page could be added by the pte walk.
406 static unsigned long __munlock_pagevec_fill(struct pagevec
*pvec
,
407 struct vm_area_struct
*vma
, int zoneid
, unsigned long start
,
414 * Initialize pte walk starting at the already pinned page where we
415 * are sure that there is a pte, as it was pinned under the same
418 pte
= get_locked_pte(vma
->vm_mm
, start
, &ptl
);
419 /* Make sure we do not cross the page table boundary */
420 end
= pgd_addr_end(start
, end
);
421 end
= pud_addr_end(start
, end
);
422 end
= pmd_addr_end(start
, end
);
424 /* The page next to the pinned page is the first we will try to get */
426 while (start
< end
) {
427 struct page
*page
= NULL
;
429 if (pte_present(*pte
))
430 page
= vm_normal_page(vma
, start
, *pte
);
432 * Break if page could not be obtained or the page's node+zone does not
435 if (!page
|| page_zone_id(page
) != zoneid
)
440 * Increase the address that will be returned *before* the
441 * eventual break due to pvec becoming full by adding the page
444 if (pagevec_add(pvec
, page
) == 0)
447 pte_unmap_unlock(pte
, ptl
);
452 * munlock_vma_pages_range() - munlock all pages in the vma range.'
453 * @vma - vma containing range to be munlock()ed.
454 * @start - start address in @vma of the range
455 * @end - end of range in @vma.
457 * For mremap(), munmap() and exit().
459 * Called with @vma VM_LOCKED.
461 * Returns with VM_LOCKED cleared. Callers must be prepared to
464 * We don't save and restore VM_LOCKED here because pages are
465 * still on lru. In unmap path, pages might be scanned by reclaim
466 * and re-mlocked by try_to_{munlock|unmap} before we unmap and
467 * free them. This will result in freeing mlocked pages.
469 void munlock_vma_pages_range(struct vm_area_struct
*vma
,
470 unsigned long start
, unsigned long end
)
472 vma
->vm_flags
&= ~VM_LOCKED
;
474 while (start
< end
) {
475 struct page
*page
= NULL
;
476 unsigned int page_mask
;
477 unsigned long page_increm
;
482 pagevec_init(&pvec
, 0);
484 * Although FOLL_DUMP is intended for get_dump_page(),
485 * it just so happens that its special treatment of the
486 * ZERO_PAGE (returning an error instead of doing get_page)
487 * suits munlock very well (and if somehow an abnormal page
488 * has sneaked into the range, we won't oops here: great).
490 page
= follow_page_mask(vma
, start
, FOLL_GET
| FOLL_DUMP
,
493 if (page
&& !IS_ERR(page
)) {
494 if (PageTransHuge(page
)) {
497 * Any THP page found by follow_page_mask() may
498 * have gotten split before reaching
499 * munlock_vma_page(), so we need to recompute
500 * the page_mask here.
502 page_mask
= munlock_vma_page(page
);
504 put_page(page
); /* follow_page_mask() */
507 * Non-huge pages are handled in batches via
508 * pagevec. The pin from follow_page_mask()
509 * prevents them from collapsing by THP.
511 pagevec_add(&pvec
, page
);
512 zone
= page_zone(page
);
513 zoneid
= page_zone_id(page
);
516 * Try to fill the rest of pagevec using fast
517 * pte walk. This will also update start to
518 * the next page to process. Then munlock the
521 start
= __munlock_pagevec_fill(&pvec
, vma
,
523 __munlock_pagevec(&pvec
, zone
);
527 /* It's a bug to munlock in the middle of a THP page */
528 VM_BUG_ON((start
>> PAGE_SHIFT
) & page_mask
);
529 page_increm
= 1 + page_mask
;
530 start
+= page_increm
* PAGE_SIZE
;
537 * mlock_fixup - handle mlock[all]/munlock[all] requests.
539 * Filters out "special" vmas -- VM_LOCKED never gets set for these, and
540 * munlock is a no-op. However, for some special vmas, we go ahead and
543 * For vmas that pass the filters, merge/split as appropriate.
545 static int mlock_fixup(struct vm_area_struct
*vma
, struct vm_area_struct
**prev
,
546 unsigned long start
, unsigned long end
, vm_flags_t newflags
)
548 struct mm_struct
*mm
= vma
->vm_mm
;
552 int lock
= !!(newflags
& VM_LOCKED
);
554 if (newflags
== vma
->vm_flags
|| (vma
->vm_flags
& VM_SPECIAL
) ||
555 is_vm_hugetlb_page(vma
) || vma
== get_gate_vma(current
->mm
))
556 goto out
; /* don't set VM_LOCKED, don't count */
558 pgoff
= vma
->vm_pgoff
+ ((start
- vma
->vm_start
) >> PAGE_SHIFT
);
559 *prev
= vma_merge(mm
, *prev
, start
, end
, newflags
, vma
->anon_vma
,
560 vma
->vm_file
, pgoff
, vma_policy(vma
));
566 if (start
!= vma
->vm_start
) {
567 ret
= split_vma(mm
, vma
, start
, 1);
572 if (end
!= vma
->vm_end
) {
573 ret
= split_vma(mm
, vma
, end
, 0);
580 * Keep track of amount of locked VM.
582 nr_pages
= (end
- start
) >> PAGE_SHIFT
;
584 nr_pages
= -nr_pages
;
585 mm
->locked_vm
+= nr_pages
;
588 * vm_flags is protected by the mmap_sem held in write mode.
589 * It's okay if try_to_unmap_one unmaps a page just after we
590 * set VM_LOCKED, __mlock_vma_pages_range will bring it back.
594 vma
->vm_flags
= newflags
;
596 munlock_vma_pages_range(vma
, start
, end
);
603 static int do_mlock(unsigned long start
, size_t len
, int on
)
605 unsigned long nstart
, end
, tmp
;
606 struct vm_area_struct
* vma
, * prev
;
609 VM_BUG_ON(start
& ~PAGE_MASK
);
610 VM_BUG_ON(len
!= PAGE_ALIGN(len
));
616 vma
= find_vma(current
->mm
, start
);
617 if (!vma
|| vma
->vm_start
> start
)
621 if (start
> vma
->vm_start
)
624 for (nstart
= start
; ; ) {
627 /* Here we know that vma->vm_start <= nstart < vma->vm_end. */
629 newflags
= vma
->vm_flags
& ~VM_LOCKED
;
631 newflags
|= VM_LOCKED
;
636 error
= mlock_fixup(vma
, &prev
, nstart
, tmp
, newflags
);
640 if (nstart
< prev
->vm_end
)
641 nstart
= prev
->vm_end
;
646 if (!vma
|| vma
->vm_start
!= nstart
) {
655 * __mm_populate - populate and/or mlock pages within a range of address space.
657 * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
658 * flags. VMAs must be already marked with the desired vm_flags, and
659 * mmap_sem must not be held.
661 int __mm_populate(unsigned long start
, unsigned long len
, int ignore_errors
)
663 struct mm_struct
*mm
= current
->mm
;
664 unsigned long end
, nstart
, nend
;
665 struct vm_area_struct
*vma
= NULL
;
669 VM_BUG_ON(start
& ~PAGE_MASK
);
670 VM_BUG_ON(len
!= PAGE_ALIGN(len
));
673 for (nstart
= start
; nstart
< end
; nstart
= nend
) {
675 * We want to fault in pages for [nstart; end) address range.
676 * Find first corresponding VMA.
680 down_read(&mm
->mmap_sem
);
681 vma
= find_vma(mm
, nstart
);
682 } else if (nstart
>= vma
->vm_end
)
684 if (!vma
|| vma
->vm_start
>= end
)
687 * Set [nstart; nend) to intersection of desired address
688 * range with the first VMA. Also, skip undesirable VMA types.
690 nend
= min(end
, vma
->vm_end
);
691 if (vma
->vm_flags
& (VM_IO
| VM_PFNMAP
))
693 if (nstart
< vma
->vm_start
)
694 nstart
= vma
->vm_start
;
696 * Now fault in a range of pages. __mlock_vma_pages_range()
697 * double checks the vma flags, so that it won't mlock pages
698 * if the vma was already munlocked.
700 ret
= __mlock_vma_pages_range(vma
, nstart
, nend
, &locked
);
704 continue; /* continue at next VMA */
706 ret
= __mlock_posix_error_return(ret
);
709 nend
= nstart
+ ret
* PAGE_SIZE
;
713 up_read(&mm
->mmap_sem
);
714 return ret
; /* 0 or negative error code */
717 SYSCALL_DEFINE2(mlock
, unsigned long, start
, size_t, len
)
719 unsigned long locked
;
720 unsigned long lock_limit
;
726 lru_add_drain_all(); /* flush pagevec */
728 len
= PAGE_ALIGN(len
+ (start
& ~PAGE_MASK
));
731 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
732 lock_limit
>>= PAGE_SHIFT
;
733 locked
= len
>> PAGE_SHIFT
;
735 down_write(¤t
->mm
->mmap_sem
);
737 locked
+= current
->mm
->locked_vm
;
739 /* check against resource limits */
740 if ((locked
<= lock_limit
) || capable(CAP_IPC_LOCK
))
741 error
= do_mlock(start
, len
, 1);
743 up_write(¤t
->mm
->mmap_sem
);
745 error
= __mm_populate(start
, len
, 0);
749 SYSCALL_DEFINE2(munlock
, unsigned long, start
, size_t, len
)
753 len
= PAGE_ALIGN(len
+ (start
& ~PAGE_MASK
));
756 down_write(¤t
->mm
->mmap_sem
);
757 ret
= do_mlock(start
, len
, 0);
758 up_write(¤t
->mm
->mmap_sem
);
763 static int do_mlockall(int flags
)
765 struct vm_area_struct
* vma
, * prev
= NULL
;
767 if (flags
& MCL_FUTURE
)
768 current
->mm
->def_flags
|= VM_LOCKED
;
770 current
->mm
->def_flags
&= ~VM_LOCKED
;
771 if (flags
== MCL_FUTURE
)
774 for (vma
= current
->mm
->mmap
; vma
; vma
= prev
->vm_next
) {
777 newflags
= vma
->vm_flags
& ~VM_LOCKED
;
778 if (flags
& MCL_CURRENT
)
779 newflags
|= VM_LOCKED
;
782 mlock_fixup(vma
, &prev
, vma
->vm_start
, vma
->vm_end
, newflags
);
789 SYSCALL_DEFINE1(mlockall
, int, flags
)
791 unsigned long lock_limit
;
794 if (!flags
|| (flags
& ~(MCL_CURRENT
| MCL_FUTURE
)))
801 if (flags
& MCL_CURRENT
)
802 lru_add_drain_all(); /* flush pagevec */
804 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
805 lock_limit
>>= PAGE_SHIFT
;
808 down_write(¤t
->mm
->mmap_sem
);
810 if (!(flags
& MCL_CURRENT
) || (current
->mm
->total_vm
<= lock_limit
) ||
811 capable(CAP_IPC_LOCK
))
812 ret
= do_mlockall(flags
);
813 up_write(¤t
->mm
->mmap_sem
);
814 if (!ret
&& (flags
& MCL_CURRENT
))
815 mm_populate(0, TASK_SIZE
);
820 SYSCALL_DEFINE0(munlockall
)
824 down_write(¤t
->mm
->mmap_sem
);
825 ret
= do_mlockall(0);
826 up_write(¤t
->mm
->mmap_sem
);
831 * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
832 * shm segments) get accounted against the user_struct instead.
834 static DEFINE_SPINLOCK(shmlock_user_lock
);
836 int user_shm_lock(size_t size
, struct user_struct
*user
)
838 unsigned long lock_limit
, locked
;
841 locked
= (size
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
842 lock_limit
= rlimit(RLIMIT_MEMLOCK
);
843 if (lock_limit
== RLIM_INFINITY
)
845 lock_limit
>>= PAGE_SHIFT
;
846 spin_lock(&shmlock_user_lock
);
848 locked
+ user
->locked_shm
> lock_limit
&& !capable(CAP_IPC_LOCK
))
851 user
->locked_shm
+= locked
;
854 spin_unlock(&shmlock_user_lock
);
858 void user_shm_unlock(size_t size
, struct user_struct
*user
)
860 spin_lock(&shmlock_user_lock
);
861 user
->locked_shm
-= (size
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
862 spin_unlock(&shmlock_user_lock
);