2 * mm/rmap.c - physical to virtual reverse mappings
4 * Copyright 2001, Rik van Riel <riel@conectiva.com.br>
5 * Released under the General Public License (GPL).
7 * Simple, low overhead reverse mapping scheme.
8 * Please try to keep this thing as modular as possible.
10 * Provides methods for unmapping each kind of mapped page:
11 * the anon methods track anonymous pages, and
12 * the file methods track pages belonging to an inode.
14 * Original design by Rik van Riel <riel@conectiva.com.br> 2001
15 * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
16 * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
17 * Contributions by Hugh Dickins <hugh@veritas.com> 2003, 2004
21 * Lock ordering in mm:
23 * inode->i_mutex (while writing or truncating, not reading or faulting)
24 * inode->i_alloc_sem (vmtruncate_range)
26 * page->flags PG_locked (lock_page)
27 * mapping->i_mmap_lock
29 * mm->page_table_lock or pte_lock
30 * zone->lru_lock (in mark_page_accessed, isolate_lru_page)
31 * swap_lock (in swap_duplicate, swap_info_get)
32 * mmlist_lock (in mmput, drain_mmlist and others)
33 * mapping->private_lock (in __set_page_dirty_buffers)
34 * inode_lock (in set_page_dirty's __mark_inode_dirty)
35 * sb_lock (within inode_lock in fs/fs-writeback.c)
36 * mapping->tree_lock (widely used, in set_page_dirty,
37 * in arch-dependent flush_dcache_mmap_lock,
38 * within inode_lock in __sync_single_inode)
42 #include <linux/pagemap.h>
43 #include <linux/swap.h>
44 #include <linux/swapops.h>
45 #include <linux/slab.h>
46 #include <linux/init.h>
47 #include <linux/rmap.h>
48 #include <linux/rcupdate.h>
49 #include <linux/module.h>
51 #include <asm/tlbflush.h>
53 struct kmem_cache
*anon_vma_cachep
;
55 static inline void validate_anon_vma(struct vm_area_struct
*find_vma
)
57 #ifdef CONFIG_DEBUG_VM
58 struct anon_vma
*anon_vma
= find_vma
->anon_vma
;
59 struct vm_area_struct
*vma
;
60 unsigned int mapcount
= 0;
63 list_for_each_entry(vma
, &anon_vma
->head
, anon_vma_node
) {
65 BUG_ON(mapcount
> 100000);
73 /* This must be called under the mmap_sem. */
74 int anon_vma_prepare(struct vm_area_struct
*vma
)
76 struct anon_vma
*anon_vma
= vma
->anon_vma
;
79 if (unlikely(!anon_vma
)) {
80 struct mm_struct
*mm
= vma
->vm_mm
;
81 struct anon_vma
*allocated
, *locked
;
83 anon_vma
= find_mergeable_anon_vma(vma
);
87 spin_lock(&locked
->lock
);
89 anon_vma
= anon_vma_alloc();
90 if (unlikely(!anon_vma
))
96 /* page_table_lock to protect against threads */
97 spin_lock(&mm
->page_table_lock
);
98 if (likely(!vma
->anon_vma
)) {
99 vma
->anon_vma
= anon_vma
;
100 list_add_tail(&vma
->anon_vma_node
, &anon_vma
->head
);
103 spin_unlock(&mm
->page_table_lock
);
106 spin_unlock(&locked
->lock
);
107 if (unlikely(allocated
))
108 anon_vma_free(allocated
);
113 void __anon_vma_merge(struct vm_area_struct
*vma
, struct vm_area_struct
*next
)
115 BUG_ON(vma
->anon_vma
!= next
->anon_vma
);
116 list_del(&next
->anon_vma_node
);
119 void __anon_vma_link(struct vm_area_struct
*vma
)
121 struct anon_vma
*anon_vma
= vma
->anon_vma
;
124 list_add_tail(&vma
->anon_vma_node
, &anon_vma
->head
);
125 validate_anon_vma(vma
);
129 void anon_vma_link(struct vm_area_struct
*vma
)
131 struct anon_vma
*anon_vma
= vma
->anon_vma
;
134 spin_lock(&anon_vma
->lock
);
135 list_add_tail(&vma
->anon_vma_node
, &anon_vma
->head
);
136 validate_anon_vma(vma
);
137 spin_unlock(&anon_vma
->lock
);
141 void anon_vma_unlink(struct vm_area_struct
*vma
)
143 struct anon_vma
*anon_vma
= vma
->anon_vma
;
149 spin_lock(&anon_vma
->lock
);
150 validate_anon_vma(vma
);
151 list_del(&vma
->anon_vma_node
);
153 /* We must garbage collect the anon_vma if it's empty */
154 empty
= list_empty(&anon_vma
->head
);
155 spin_unlock(&anon_vma
->lock
);
158 anon_vma_free(anon_vma
);
161 static void anon_vma_ctor(void *data
, struct kmem_cache
*cachep
,
164 if ((flags
& (SLAB_CTOR_VERIFY
|SLAB_CTOR_CONSTRUCTOR
)) ==
165 SLAB_CTOR_CONSTRUCTOR
) {
166 struct anon_vma
*anon_vma
= data
;
168 spin_lock_init(&anon_vma
->lock
);
169 INIT_LIST_HEAD(&anon_vma
->head
);
173 void __init
anon_vma_init(void)
175 anon_vma_cachep
= kmem_cache_create("anon_vma", sizeof(struct anon_vma
),
176 0, SLAB_DESTROY_BY_RCU
|SLAB_PANIC
, anon_vma_ctor
, NULL
);
180 * Getting a lock on a stable anon_vma from a page off the LRU is
181 * tricky: page_lock_anon_vma rely on RCU to guard against the races.
183 static struct anon_vma
*page_lock_anon_vma(struct page
*page
)
185 struct anon_vma
*anon_vma
= NULL
;
186 unsigned long anon_mapping
;
189 anon_mapping
= (unsigned long) page
->mapping
;
190 if (!(anon_mapping
& PAGE_MAPPING_ANON
))
192 if (!page_mapped(page
))
195 anon_vma
= (struct anon_vma
*) (anon_mapping
- PAGE_MAPPING_ANON
);
196 spin_lock(&anon_vma
->lock
);
203 * At what user virtual address is page expected in vma?
205 static inline unsigned long
206 vma_address(struct page
*page
, struct vm_area_struct
*vma
)
208 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
209 unsigned long address
;
211 address
= vma
->vm_start
+ ((pgoff
- vma
->vm_pgoff
) << PAGE_SHIFT
);
212 if (unlikely(address
< vma
->vm_start
|| address
>= vma
->vm_end
)) {
213 /* page should be within any vma from prio_tree_next */
214 BUG_ON(!PageAnon(page
));
221 * At what user virtual address is page expected in vma? checking that the
222 * page matches the vma: currently only used on anon pages, by unuse_vma;
224 unsigned long page_address_in_vma(struct page
*page
, struct vm_area_struct
*vma
)
226 if (PageAnon(page
)) {
227 if ((void *)vma
->anon_vma
!=
228 (void *)page
->mapping
- PAGE_MAPPING_ANON
)
230 } else if (page
->mapping
&& !(vma
->vm_flags
& VM_NONLINEAR
)) {
232 vma
->vm_file
->f_mapping
!= page
->mapping
)
236 return vma_address(page
, vma
);
240 * Check that @page is mapped at @address into @mm.
242 * On success returns with pte mapped and locked.
244 pte_t
*page_check_address(struct page
*page
, struct mm_struct
*mm
,
245 unsigned long address
, spinlock_t
**ptlp
)
253 pgd
= pgd_offset(mm
, address
);
254 if (!pgd_present(*pgd
))
257 pud
= pud_offset(pgd
, address
);
258 if (!pud_present(*pud
))
261 pmd
= pmd_offset(pud
, address
);
262 if (!pmd_present(*pmd
))
265 pte
= pte_offset_map(pmd
, address
);
266 /* Make a quick check before getting the lock */
267 if (!pte_present(*pte
)) {
272 ptl
= pte_lockptr(mm
, pmd
);
274 if (pte_present(*pte
) && page_to_pfn(page
) == pte_pfn(*pte
)) {
278 pte_unmap_unlock(pte
, ptl
);
283 * Subfunctions of page_referenced: page_referenced_one called
284 * repeatedly from either page_referenced_anon or page_referenced_file.
286 static int page_referenced_one(struct page
*page
,
287 struct vm_area_struct
*vma
, unsigned int *mapcount
)
289 struct mm_struct
*mm
= vma
->vm_mm
;
290 unsigned long address
;
295 address
= vma_address(page
, vma
);
296 if (address
== -EFAULT
)
299 pte
= page_check_address(page
, mm
, address
, &ptl
);
303 if (ptep_clear_flush_young(vma
, address
, pte
))
306 /* Pretend the page is referenced if the task has the
307 swap token and is in the middle of a page fault. */
308 if (mm
!= current
->mm
&& has_swap_token(mm
) &&
309 rwsem_is_locked(&mm
->mmap_sem
))
313 pte_unmap_unlock(pte
, ptl
);
318 static int page_referenced_anon(struct page
*page
)
320 unsigned int mapcount
;
321 struct anon_vma
*anon_vma
;
322 struct vm_area_struct
*vma
;
325 anon_vma
= page_lock_anon_vma(page
);
329 mapcount
= page_mapcount(page
);
330 list_for_each_entry(vma
, &anon_vma
->head
, anon_vma_node
) {
331 referenced
+= page_referenced_one(page
, vma
, &mapcount
);
335 spin_unlock(&anon_vma
->lock
);
340 * page_referenced_file - referenced check for object-based rmap
341 * @page: the page we're checking references on.
343 * For an object-based mapped page, find all the places it is mapped and
344 * check/clear the referenced flag. This is done by following the page->mapping
345 * pointer, then walking the chain of vmas it holds. It returns the number
346 * of references it found.
348 * This function is only called from page_referenced for object-based pages.
350 static int page_referenced_file(struct page
*page
)
352 unsigned int mapcount
;
353 struct address_space
*mapping
= page
->mapping
;
354 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
355 struct vm_area_struct
*vma
;
356 struct prio_tree_iter iter
;
360 * The caller's checks on page->mapping and !PageAnon have made
361 * sure that this is a file page: the check for page->mapping
362 * excludes the case just before it gets set on an anon page.
364 BUG_ON(PageAnon(page
));
367 * The page lock not only makes sure that page->mapping cannot
368 * suddenly be NULLified by truncation, it makes sure that the
369 * structure at mapping cannot be freed and reused yet,
370 * so we can safely take mapping->i_mmap_lock.
372 BUG_ON(!PageLocked(page
));
374 spin_lock(&mapping
->i_mmap_lock
);
377 * i_mmap_lock does not stabilize mapcount at all, but mapcount
378 * is more likely to be accurate if we note it after spinning.
380 mapcount
= page_mapcount(page
);
382 vma_prio_tree_foreach(vma
, &iter
, &mapping
->i_mmap
, pgoff
, pgoff
) {
383 if ((vma
->vm_flags
& (VM_LOCKED
|VM_MAYSHARE
))
384 == (VM_LOCKED
|VM_MAYSHARE
)) {
388 referenced
+= page_referenced_one(page
, vma
, &mapcount
);
393 spin_unlock(&mapping
->i_mmap_lock
);
398 * page_referenced - test if the page was referenced
399 * @page: the page to test
400 * @is_locked: caller holds lock on the page
402 * Quick test_and_clear_referenced for all mappings to a page,
403 * returns the number of ptes which referenced the page.
405 int page_referenced(struct page
*page
, int is_locked
)
409 if (page_test_and_clear_young(page
))
412 if (TestClearPageReferenced(page
))
415 if (page_mapped(page
) && page
->mapping
) {
417 referenced
+= page_referenced_anon(page
);
419 referenced
+= page_referenced_file(page
);
420 else if (TestSetPageLocked(page
))
424 referenced
+= page_referenced_file(page
);
431 static int page_mkclean_one(struct page
*page
, struct vm_area_struct
*vma
)
433 struct mm_struct
*mm
= vma
->vm_mm
;
434 unsigned long address
;
439 address
= vma_address(page
, vma
);
440 if (address
== -EFAULT
)
443 pte
= page_check_address(page
, mm
, address
, &ptl
);
447 if (!pte_dirty(*pte
) && !pte_write(*pte
))
450 entry
= ptep_get_and_clear(mm
, address
, pte
);
451 entry
= pte_mkclean(entry
);
452 entry
= pte_wrprotect(entry
);
453 ptep_establish(vma
, address
, pte
, entry
);
454 lazy_mmu_prot_update(entry
);
458 pte_unmap_unlock(pte
, ptl
);
463 static int page_mkclean_file(struct address_space
*mapping
, struct page
*page
)
465 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
466 struct vm_area_struct
*vma
;
467 struct prio_tree_iter iter
;
470 BUG_ON(PageAnon(page
));
472 spin_lock(&mapping
->i_mmap_lock
);
473 vma_prio_tree_foreach(vma
, &iter
, &mapping
->i_mmap
, pgoff
, pgoff
) {
474 if (vma
->vm_flags
& VM_SHARED
)
475 ret
+= page_mkclean_one(page
, vma
);
477 spin_unlock(&mapping
->i_mmap_lock
);
481 int page_mkclean(struct page
*page
)
485 BUG_ON(!PageLocked(page
));
487 if (page_mapped(page
)) {
488 struct address_space
*mapping
= page_mapping(page
);
490 ret
= page_mkclean_file(mapping
, page
);
497 * page_set_anon_rmap - setup new anonymous rmap
498 * @page: the page to add the mapping to
499 * @vma: the vm area in which the mapping is added
500 * @address: the user virtual address mapped
502 static void __page_set_anon_rmap(struct page
*page
,
503 struct vm_area_struct
*vma
, unsigned long address
)
505 struct anon_vma
*anon_vma
= vma
->anon_vma
;
508 anon_vma
= (void *) anon_vma
+ PAGE_MAPPING_ANON
;
509 page
->mapping
= (struct address_space
*) anon_vma
;
511 page
->index
= linear_page_index(vma
, address
);
514 * nr_mapped state can be updated without turning off
515 * interrupts because it is not modified via interrupt.
517 __inc_zone_page_state(page
, NR_ANON_PAGES
);
521 * page_add_anon_rmap - add pte mapping to an anonymous page
522 * @page: the page to add the mapping to
523 * @vma: the vm area in which the mapping is added
524 * @address: the user virtual address mapped
526 * The caller needs to hold the pte lock.
528 void page_add_anon_rmap(struct page
*page
,
529 struct vm_area_struct
*vma
, unsigned long address
)
531 if (atomic_inc_and_test(&page
->_mapcount
))
532 __page_set_anon_rmap(page
, vma
, address
);
533 /* else checking page index and mapping is racy */
537 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
538 * @page: the page to add the mapping to
539 * @vma: the vm area in which the mapping is added
540 * @address: the user virtual address mapped
542 * Same as page_add_anon_rmap but must only be called on *new* pages.
543 * This means the inc-and-test can be bypassed.
545 void page_add_new_anon_rmap(struct page
*page
,
546 struct vm_area_struct
*vma
, unsigned long address
)
548 atomic_set(&page
->_mapcount
, 0); /* elevate count by 1 (starts at -1) */
549 __page_set_anon_rmap(page
, vma
, address
);
553 * page_add_file_rmap - add pte mapping to a file page
554 * @page: the page to add the mapping to
556 * The caller needs to hold the pte lock.
558 void page_add_file_rmap(struct page
*page
)
560 if (atomic_inc_and_test(&page
->_mapcount
))
561 __inc_zone_page_state(page
, NR_FILE_MAPPED
);
565 * page_remove_rmap - take down pte mapping from a page
566 * @page: page to remove mapping from
568 * The caller needs to hold the pte lock.
570 void page_remove_rmap(struct page
*page
)
572 if (atomic_add_negative(-1, &page
->_mapcount
)) {
573 if (unlikely(page_mapcount(page
) < 0)) {
574 printk (KERN_EMERG
"Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page
));
575 printk (KERN_EMERG
" page->flags = %lx\n", page
->flags
);
576 printk (KERN_EMERG
" page->count = %x\n", page_count(page
));
577 printk (KERN_EMERG
" page->mapping = %p\n", page
->mapping
);
582 * It would be tidy to reset the PageAnon mapping here,
583 * but that might overwrite a racing page_add_anon_rmap
584 * which increments mapcount after us but sets mapping
585 * before us: so leave the reset to free_hot_cold_page,
586 * and remember that it's only reliable while mapped.
587 * Leaving it set also helps swapoff to reinstate ptes
588 * faster for those pages still in swapcache.
590 if (page_test_and_clear_dirty(page
))
591 set_page_dirty(page
);
592 __dec_zone_page_state(page
,
593 PageAnon(page
) ? NR_ANON_PAGES
: NR_FILE_MAPPED
);
598 * Subfunctions of try_to_unmap: try_to_unmap_one called
599 * repeatedly from either try_to_unmap_anon or try_to_unmap_file.
601 static int try_to_unmap_one(struct page
*page
, struct vm_area_struct
*vma
,
604 struct mm_struct
*mm
= vma
->vm_mm
;
605 unsigned long address
;
609 int ret
= SWAP_AGAIN
;
611 address
= vma_address(page
, vma
);
612 if (address
== -EFAULT
)
615 pte
= page_check_address(page
, mm
, address
, &ptl
);
620 * If the page is mlock()d, we cannot swap it out.
621 * If it's recently referenced (perhaps page_referenced
622 * skipped over this mm) then we should reactivate it.
624 if (!migration
&& ((vma
->vm_flags
& VM_LOCKED
) ||
625 (ptep_clear_flush_young(vma
, address
, pte
)))) {
630 /* Nuke the page table entry. */
631 flush_cache_page(vma
, address
, page_to_pfn(page
));
632 pteval
= ptep_clear_flush(vma
, address
, pte
);
634 /* Move the dirty bit to the physical page now the pte is gone. */
635 if (pte_dirty(pteval
))
636 set_page_dirty(page
);
638 /* Update high watermark before we lower rss */
639 update_hiwater_rss(mm
);
641 if (PageAnon(page
)) {
642 swp_entry_t entry
= { .val
= page_private(page
) };
644 if (PageSwapCache(page
)) {
646 * Store the swap location in the pte.
647 * See handle_pte_fault() ...
649 swap_duplicate(entry
);
650 if (list_empty(&mm
->mmlist
)) {
651 spin_lock(&mmlist_lock
);
652 if (list_empty(&mm
->mmlist
))
653 list_add(&mm
->mmlist
, &init_mm
.mmlist
);
654 spin_unlock(&mmlist_lock
);
656 dec_mm_counter(mm
, anon_rss
);
657 #ifdef CONFIG_MIGRATION
660 * Store the pfn of the page in a special migration
661 * pte. do_swap_page() will wait until the migration
662 * pte is removed and then restart fault handling.
665 entry
= make_migration_entry(page
, pte_write(pteval
));
668 set_pte_at(mm
, address
, pte
, swp_entry_to_pte(entry
));
669 BUG_ON(pte_file(*pte
));
671 #ifdef CONFIG_MIGRATION
673 /* Establish migration entry for a file page */
675 entry
= make_migration_entry(page
, pte_write(pteval
));
676 set_pte_at(mm
, address
, pte
, swp_entry_to_pte(entry
));
679 dec_mm_counter(mm
, file_rss
);
682 page_remove_rmap(page
);
683 page_cache_release(page
);
686 pte_unmap_unlock(pte
, ptl
);
692 * objrmap doesn't work for nonlinear VMAs because the assumption that
693 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
694 * Consequently, given a particular page and its ->index, we cannot locate the
695 * ptes which are mapping that page without an exhaustive linear search.
697 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
698 * maps the file to which the target page belongs. The ->vm_private_data field
699 * holds the current cursor into that scan. Successive searches will circulate
700 * around the vma's virtual address space.
702 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
703 * more scanning pressure is placed against them as well. Eventually pages
704 * will become fully unmapped and are eligible for eviction.
706 * For very sparsely populated VMAs this is a little inefficient - chances are
707 * there there won't be many ptes located within the scan cluster. In this case
708 * maybe we could scan further - to the end of the pte page, perhaps.
710 #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
711 #define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
713 static void try_to_unmap_cluster(unsigned long cursor
,
714 unsigned int *mapcount
, struct vm_area_struct
*vma
)
716 struct mm_struct
*mm
= vma
->vm_mm
;
724 unsigned long address
;
727 address
= (vma
->vm_start
+ cursor
) & CLUSTER_MASK
;
728 end
= address
+ CLUSTER_SIZE
;
729 if (address
< vma
->vm_start
)
730 address
= vma
->vm_start
;
731 if (end
> vma
->vm_end
)
734 pgd
= pgd_offset(mm
, address
);
735 if (!pgd_present(*pgd
))
738 pud
= pud_offset(pgd
, address
);
739 if (!pud_present(*pud
))
742 pmd
= pmd_offset(pud
, address
);
743 if (!pmd_present(*pmd
))
746 pte
= pte_offset_map_lock(mm
, pmd
, address
, &ptl
);
748 /* Update high watermark before we lower rss */
749 update_hiwater_rss(mm
);
751 for (; address
< end
; pte
++, address
+= PAGE_SIZE
) {
752 if (!pte_present(*pte
))
754 page
= vm_normal_page(vma
, address
, *pte
);
755 BUG_ON(!page
|| PageAnon(page
));
757 if (ptep_clear_flush_young(vma
, address
, pte
))
760 /* Nuke the page table entry. */
761 flush_cache_page(vma
, address
, pte_pfn(*pte
));
762 pteval
= ptep_clear_flush(vma
, address
, pte
);
764 /* If nonlinear, store the file page offset in the pte. */
765 if (page
->index
!= linear_page_index(vma
, address
))
766 set_pte_at(mm
, address
, pte
, pgoff_to_pte(page
->index
));
768 /* Move the dirty bit to the physical page now the pte is gone. */
769 if (pte_dirty(pteval
))
770 set_page_dirty(page
);
772 page_remove_rmap(page
);
773 page_cache_release(page
);
774 dec_mm_counter(mm
, file_rss
);
777 pte_unmap_unlock(pte
- 1, ptl
);
780 static int try_to_unmap_anon(struct page
*page
, int migration
)
782 struct anon_vma
*anon_vma
;
783 struct vm_area_struct
*vma
;
784 int ret
= SWAP_AGAIN
;
786 anon_vma
= page_lock_anon_vma(page
);
790 list_for_each_entry(vma
, &anon_vma
->head
, anon_vma_node
) {
791 ret
= try_to_unmap_one(page
, vma
, migration
);
792 if (ret
== SWAP_FAIL
|| !page_mapped(page
))
795 spin_unlock(&anon_vma
->lock
);
800 * try_to_unmap_file - unmap file page using the object-based rmap method
801 * @page: the page to unmap
803 * Find all the mappings of a page using the mapping pointer and the vma chains
804 * contained in the address_space struct it points to.
806 * This function is only called from try_to_unmap for object-based pages.
808 static int try_to_unmap_file(struct page
*page
, int migration
)
810 struct address_space
*mapping
= page
->mapping
;
811 pgoff_t pgoff
= page
->index
<< (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
812 struct vm_area_struct
*vma
;
813 struct prio_tree_iter iter
;
814 int ret
= SWAP_AGAIN
;
815 unsigned long cursor
;
816 unsigned long max_nl_cursor
= 0;
817 unsigned long max_nl_size
= 0;
818 unsigned int mapcount
;
820 spin_lock(&mapping
->i_mmap_lock
);
821 vma_prio_tree_foreach(vma
, &iter
, &mapping
->i_mmap
, pgoff
, pgoff
) {
822 ret
= try_to_unmap_one(page
, vma
, migration
);
823 if (ret
== SWAP_FAIL
|| !page_mapped(page
))
827 if (list_empty(&mapping
->i_mmap_nonlinear
))
830 list_for_each_entry(vma
, &mapping
->i_mmap_nonlinear
,
831 shared
.vm_set
.list
) {
832 if ((vma
->vm_flags
& VM_LOCKED
) && !migration
)
834 cursor
= (unsigned long) vma
->vm_private_data
;
835 if (cursor
> max_nl_cursor
)
836 max_nl_cursor
= cursor
;
837 cursor
= vma
->vm_end
- vma
->vm_start
;
838 if (cursor
> max_nl_size
)
839 max_nl_size
= cursor
;
842 if (max_nl_size
== 0) { /* any nonlinears locked or reserved */
848 * We don't try to search for this page in the nonlinear vmas,
849 * and page_referenced wouldn't have found it anyway. Instead
850 * just walk the nonlinear vmas trying to age and unmap some.
851 * The mapcount of the page we came in with is irrelevant,
852 * but even so use it as a guide to how hard we should try?
854 mapcount
= page_mapcount(page
);
857 cond_resched_lock(&mapping
->i_mmap_lock
);
859 max_nl_size
= (max_nl_size
+ CLUSTER_SIZE
- 1) & CLUSTER_MASK
;
860 if (max_nl_cursor
== 0)
861 max_nl_cursor
= CLUSTER_SIZE
;
864 list_for_each_entry(vma
, &mapping
->i_mmap_nonlinear
,
865 shared
.vm_set
.list
) {
866 if ((vma
->vm_flags
& VM_LOCKED
) && !migration
)
868 cursor
= (unsigned long) vma
->vm_private_data
;
869 while ( cursor
< max_nl_cursor
&&
870 cursor
< vma
->vm_end
- vma
->vm_start
) {
871 try_to_unmap_cluster(cursor
, &mapcount
, vma
);
872 cursor
+= CLUSTER_SIZE
;
873 vma
->vm_private_data
= (void *) cursor
;
874 if ((int)mapcount
<= 0)
877 vma
->vm_private_data
= (void *) max_nl_cursor
;
879 cond_resched_lock(&mapping
->i_mmap_lock
);
880 max_nl_cursor
+= CLUSTER_SIZE
;
881 } while (max_nl_cursor
<= max_nl_size
);
884 * Don't loop forever (perhaps all the remaining pages are
885 * in locked vmas). Reset cursor on all unreserved nonlinear
886 * vmas, now forgetting on which ones it had fallen behind.
888 list_for_each_entry(vma
, &mapping
->i_mmap_nonlinear
, shared
.vm_set
.list
)
889 vma
->vm_private_data
= NULL
;
891 spin_unlock(&mapping
->i_mmap_lock
);
896 * try_to_unmap - try to remove all page table mappings to a page
897 * @page: the page to get unmapped
899 * Tries to remove all the page table entries which are mapping this
900 * page, used in the pageout path. Caller must hold the page lock.
903 * SWAP_SUCCESS - we succeeded in removing all mappings
904 * SWAP_AGAIN - we missed a mapping, try again later
905 * SWAP_FAIL - the page is unswappable
907 int try_to_unmap(struct page
*page
, int migration
)
911 BUG_ON(!PageLocked(page
));
914 ret
= try_to_unmap_anon(page
, migration
);
916 ret
= try_to_unmap_file(page
, migration
);
918 if (!page_mapped(page
))
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