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)
26 * When a page fault occurs in writing from user to file, down_read
27 * of mmap_sem nests within i_mutex; in sys_msync, i_mutex nests within
28 * down_read of mmap_sem; i_mutex and down_write of mmap_sem are never
29 * taken together; in truncation, i_mutex is taken outermost.
32 * page->flags PG_locked (lock_page)
33 * mapping->i_mmap_lock
35 * mm->page_table_lock or pte_lock
36 * zone->lru_lock (in mark_page_accessed, isolate_lru_page)
37 * swap_lock (in swap_duplicate, swap_info_get)
38 * mmlist_lock (in mmput, drain_mmlist and others)
39 * mapping->private_lock (in __set_page_dirty_buffers)
40 * inode_lock (in set_page_dirty's __mark_inode_dirty)
41 * sb_lock (within inode_lock in fs/fs-writeback.c)
42 * mapping->tree_lock (widely used, in set_page_dirty,
43 * in arch-dependent flush_dcache_mmap_lock,
44 * within inode_lock in __sync_single_inode)
48 #include <linux/pagemap.h>
49 #include <linux/swap.h>
50 #include <linux/swapops.h>
51 #include <linux/slab.h>
52 #include <linux/init.h>
53 #include <linux/rmap.h>
54 #include <linux/rcupdate.h>
55 #include <linux/module.h>
56 #include <linux/kallsyms.h>
57 #include <linux/vs_memory.h>
59 #include <asm/tlbflush.h>
61 struct kmem_cache *anon_vma_cachep;
63 static inline void validate_anon_vma(struct vm_area_struct *find_vma)
65 #ifdef CONFIG_DEBUG_VM
66 struct anon_vma *anon_vma = find_vma->anon_vma;
67 struct vm_area_struct *vma;
68 unsigned int mapcount = 0;
71 list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
73 BUG_ON(mapcount > 100000);
81 /* This must be called under the mmap_sem. */
82 int anon_vma_prepare(struct vm_area_struct *vma)
84 struct anon_vma *anon_vma = vma->anon_vma;
87 if (unlikely(!anon_vma)) {
88 struct mm_struct *mm = vma->vm_mm;
89 struct anon_vma *allocated, *locked;
91 anon_vma = find_mergeable_anon_vma(vma);
95 spin_lock(&locked->lock);
97 anon_vma = anon_vma_alloc();
98 if (unlikely(!anon_vma))
100 allocated = anon_vma;
104 /* page_table_lock to protect against threads */
105 spin_lock(&mm->page_table_lock);
106 if (likely(!vma->anon_vma)) {
107 vma->anon_vma = anon_vma;
108 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
111 spin_unlock(&mm->page_table_lock);
114 spin_unlock(&locked->lock);
115 if (unlikely(allocated))
116 anon_vma_free(allocated);
121 void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next)
123 BUG_ON(vma->anon_vma != next->anon_vma);
124 list_del(&next->anon_vma_node);
127 void __anon_vma_link(struct vm_area_struct *vma)
129 struct anon_vma *anon_vma = vma->anon_vma;
132 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
133 validate_anon_vma(vma);
137 void anon_vma_link(struct vm_area_struct *vma)
139 struct anon_vma *anon_vma = vma->anon_vma;
142 spin_lock(&anon_vma->lock);
143 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
144 validate_anon_vma(vma);
145 spin_unlock(&anon_vma->lock);
149 void anon_vma_unlink(struct vm_area_struct *vma)
151 struct anon_vma *anon_vma = vma->anon_vma;
157 spin_lock(&anon_vma->lock);
158 validate_anon_vma(vma);
159 list_del(&vma->anon_vma_node);
161 /* We must garbage collect the anon_vma if it's empty */
162 empty = list_empty(&anon_vma->head);
163 spin_unlock(&anon_vma->lock);
166 anon_vma_free(anon_vma);
169 static void anon_vma_ctor(void *data, struct kmem_cache *cachep,
172 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
173 SLAB_CTOR_CONSTRUCTOR) {
174 struct anon_vma *anon_vma = data;
176 spin_lock_init(&anon_vma->lock);
177 INIT_LIST_HEAD(&anon_vma->head);
181 void __init anon_vma_init(void)
183 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
184 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor, NULL);
188 * Getting a lock on a stable anon_vma from a page off the LRU is
189 * tricky: page_lock_anon_vma rely on RCU to guard against the races.
191 static struct anon_vma *page_lock_anon_vma(struct page *page)
193 struct anon_vma *anon_vma = NULL;
194 unsigned long anon_mapping;
197 anon_mapping = (unsigned long) page->mapping;
198 if (!(anon_mapping & PAGE_MAPPING_ANON))
200 if (!page_mapped(page))
203 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
204 spin_lock(&anon_vma->lock);
211 * At what user virtual address is page expected in vma?
213 static inline unsigned long
214 vma_address(struct page *page, struct vm_area_struct *vma)
216 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
217 unsigned long address;
219 address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
220 if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
221 /* page should be within any vma from prio_tree_next */
222 BUG_ON(!PageAnon(page));
229 * At what user virtual address is page expected in vma? checking that the
230 * page matches the vma: currently only used on anon pages, by unuse_vma;
232 unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
234 if (PageAnon(page)) {
235 if ((void *)vma->anon_vma !=
236 (void *)page->mapping - PAGE_MAPPING_ANON)
238 } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
240 vma->vm_file->f_mapping != page->mapping)
244 return vma_address(page, vma);
248 * Check that @page is mapped at @address into @mm.
250 * On success returns with pte mapped and locked.
252 pte_t *page_check_address(struct page *page, struct mm_struct *mm,
253 unsigned long address, spinlock_t **ptlp)
261 pgd = pgd_offset(mm, address);
262 if (!pgd_present(*pgd))
265 pud = pud_offset(pgd, address);
266 if (!pud_present(*pud))
269 pmd = pmd_offset(pud, address);
270 if (!pmd_present(*pmd))
273 pte = pte_offset_map(pmd, address);
274 /* Make a quick check before getting the lock */
275 if (!pte_present(*pte)) {
280 ptl = pte_lockptr(mm, pmd);
282 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
286 pte_unmap_unlock(pte, ptl);
291 * Subfunctions of page_referenced: page_referenced_one called
292 * repeatedly from either page_referenced_anon or page_referenced_file.
294 static int page_referenced_one(struct page *page,
295 struct vm_area_struct *vma, unsigned int *mapcount)
297 struct mm_struct *mm = vma->vm_mm;
298 unsigned long address;
303 address = vma_address(page, vma);
304 if (address == -EFAULT)
307 pte = page_check_address(page, mm, address, &ptl);
311 if (ptep_clear_flush_young(vma, address, pte))
314 /* Pretend the page is referenced if the task has the
315 swap token and is in the middle of a page fault. */
316 if (mm != current->mm && has_swap_token(mm) &&
317 rwsem_is_locked(&mm->mmap_sem))
321 pte_unmap_unlock(pte, ptl);
326 static int page_referenced_anon(struct page *page)
328 unsigned int mapcount;
329 struct anon_vma *anon_vma;
330 struct vm_area_struct *vma;
333 anon_vma = page_lock_anon_vma(page);
337 mapcount = page_mapcount(page);
338 list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
339 referenced += page_referenced_one(page, vma, &mapcount);
343 spin_unlock(&anon_vma->lock);
348 * page_referenced_file - referenced check for object-based rmap
349 * @page: the page we're checking references on.
351 * For an object-based mapped page, find all the places it is mapped and
352 * check/clear the referenced flag. This is done by following the page->mapping
353 * pointer, then walking the chain of vmas it holds. It returns the number
354 * of references it found.
356 * This function is only called from page_referenced for object-based pages.
358 static int page_referenced_file(struct page *page)
360 unsigned int mapcount;
361 struct address_space *mapping = page->mapping;
362 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
363 struct vm_area_struct *vma;
364 struct prio_tree_iter iter;
368 * The caller's checks on page->mapping and !PageAnon have made
369 * sure that this is a file page: the check for page->mapping
370 * excludes the case just before it gets set on an anon page.
372 BUG_ON(PageAnon(page));
375 * The page lock not only makes sure that page->mapping cannot
376 * suddenly be NULLified by truncation, it makes sure that the
377 * structure at mapping cannot be freed and reused yet,
378 * so we can safely take mapping->i_mmap_lock.
380 BUG_ON(!PageLocked(page));
382 spin_lock(&mapping->i_mmap_lock);
385 * i_mmap_lock does not stabilize mapcount at all, but mapcount
386 * is more likely to be accurate if we note it after spinning.
388 mapcount = page_mapcount(page);
390 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
391 if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE))
392 == (VM_LOCKED|VM_MAYSHARE)) {
396 referenced += page_referenced_one(page, vma, &mapcount);
401 spin_unlock(&mapping->i_mmap_lock);
406 * page_referenced - test if the page was referenced
407 * @page: the page to test
408 * @is_locked: caller holds lock on the page
410 * Quick test_and_clear_referenced for all mappings to a page,
411 * returns the number of ptes which referenced the page.
413 int page_referenced(struct page *page, int is_locked)
417 if (page_test_and_clear_young(page))
420 if (TestClearPageReferenced(page))
423 if (page_mapped(page) && page->mapping) {
425 referenced += page_referenced_anon(page);
427 referenced += page_referenced_file(page);
428 else if (TestSetPageLocked(page))
432 referenced += page_referenced_file(page);
439 static int page_mkclean_one(struct page *page, struct vm_area_struct *vma)
441 struct mm_struct *mm = vma->vm_mm;
442 unsigned long address;
447 address = vma_address(page, vma);
448 if (address == -EFAULT)
451 pte = page_check_address(page, mm, address, &ptl);
455 if (!pte_dirty(*pte) && !pte_write(*pte))
458 entry = ptep_get_and_clear(mm, address, pte);
459 entry = pte_mkclean(entry);
460 entry = pte_wrprotect(entry);
461 ptep_establish(vma, address, pte, entry);
462 lazy_mmu_prot_update(entry);
466 pte_unmap_unlock(pte, ptl);
471 static int page_mkclean_file(struct address_space *mapping, struct page *page)
473 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
474 struct vm_area_struct *vma;
475 struct prio_tree_iter iter;
478 BUG_ON(PageAnon(page));
480 spin_lock(&mapping->i_mmap_lock);
481 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
482 if (vma->vm_flags & VM_SHARED)
483 ret += page_mkclean_one(page, vma);
485 spin_unlock(&mapping->i_mmap_lock);
489 int page_mkclean(struct page *page)
493 WARN_ON_ONCE(!PageLocked(page));
495 if (page_mapped(page)) {
496 struct address_space *mapping = page_mapping(page);
498 ret = page_mkclean_file(mapping, page);
505 * page_set_anon_rmap - setup new anonymous rmap
506 * @page: the page to add the mapping to
507 * @vma: the vm area in which the mapping is added
508 * @address: the user virtual address mapped
510 static void __page_set_anon_rmap(struct page *page,
511 struct vm_area_struct *vma, unsigned long address)
513 struct anon_vma *anon_vma = vma->anon_vma;
516 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
517 page->mapping = (struct address_space *) anon_vma;
519 page->index = linear_page_index(vma, address);
522 * nr_mapped state can be updated without turning off
523 * interrupts because it is not modified via interrupt.
525 __inc_zone_page_state(page, NR_ANON_PAGES);
529 * page_add_anon_rmap - add pte mapping to an anonymous page
530 * @page: the page to add the mapping to
531 * @vma: the vm area in which the mapping is added
532 * @address: the user virtual address mapped
534 * The caller needs to hold the pte lock.
536 void page_add_anon_rmap(struct page *page,
537 struct vm_area_struct *vma, unsigned long address)
539 if (atomic_inc_and_test(&page->_mapcount))
540 __page_set_anon_rmap(page, vma, address);
541 /* else checking page index and mapping is racy */
545 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
546 * @page: the page to add the mapping to
547 * @vma: the vm area in which the mapping is added
548 * @address: the user virtual address mapped
550 * Same as page_add_anon_rmap but must only be called on *new* pages.
551 * This means the inc-and-test can be bypassed.
553 void page_add_new_anon_rmap(struct page *page,
554 struct vm_area_struct *vma, unsigned long address)
556 atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */
557 __page_set_anon_rmap(page, vma, address);
561 * page_add_file_rmap - add pte mapping to a file page
562 * @page: the page to add the mapping to
564 * The caller needs to hold the pte lock.
566 void page_add_file_rmap(struct page *page)
568 if (atomic_inc_and_test(&page->_mapcount))
569 __inc_zone_page_state(page, NR_FILE_MAPPED);
573 * page_remove_rmap - take down pte mapping from a page
574 * @page: page to remove mapping from
576 * The caller needs to hold the pte lock.
578 void page_remove_rmap(struct page *page, struct vm_area_struct *vma)
580 if (atomic_add_negative(-1, &page->_mapcount)) {
581 if (unlikely(page_mapcount(page) < 0)) {
582 printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page));
583 printk (KERN_EMERG " page->flags = %lx\n", page->flags);
584 printk (KERN_EMERG " page->count = %x\n", page_count(page));
585 printk (KERN_EMERG " page->mapping = %p\n", page->mapping);
587 print_symbol (KERN_EMERG " vma->vm_ops->nopage = %s\n", (unsigned long)vma->vm_ops->nopage);
591 * It would be tidy to reset the PageAnon mapping here,
592 * but that might overwrite a racing page_add_anon_rmap
593 * which increments mapcount after us but sets mapping
594 * before us: so leave the reset to free_hot_cold_page,
595 * and remember that it's only reliable while mapped.
596 * Leaving it set also helps swapoff to reinstate ptes
597 * faster for those pages still in swapcache.
599 if (page_test_and_clear_dirty(page))
600 set_page_dirty(page);
601 __dec_zone_page_state(page,
602 PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
607 * Subfunctions of try_to_unmap: try_to_unmap_one called
608 * repeatedly from either try_to_unmap_anon or try_to_unmap_file.
610 static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
613 struct mm_struct *mm = vma->vm_mm;
614 unsigned long address;
618 int ret = SWAP_AGAIN;
620 address = vma_address(page, vma);
621 if (address == -EFAULT)
624 pte = page_check_address(page, mm, address, &ptl);
629 * If the page is mlock()d, we cannot swap it out.
630 * If it's recently referenced (perhaps page_referenced
631 * skipped over this mm) then we should reactivate it.
633 if (!migration && ((vma->vm_flags & VM_LOCKED) ||
634 (ptep_clear_flush_young(vma, address, pte)))) {
639 /* Nuke the page table entry. */
640 flush_cache_page(vma, address, page_to_pfn(page));
641 pteval = ptep_clear_flush(vma, address, pte);
643 /* Move the dirty bit to the physical page now the pte is gone. */
644 if (pte_dirty(pteval))
645 set_page_dirty(page);
647 /* Update high watermark before we lower rss */
648 update_hiwater_rss(mm);
650 if (PageAnon(page)) {
651 swp_entry_t entry = { .val = page_private(page) };
653 if (PageSwapCache(page)) {
655 * Store the swap location in the pte.
656 * See handle_pte_fault() ...
658 swap_duplicate(entry);
659 if (list_empty(&mm->mmlist)) {
660 spin_lock(&mmlist_lock);
661 if (list_empty(&mm->mmlist))
662 list_add(&mm->mmlist, &init_mm.mmlist);
663 spin_unlock(&mmlist_lock);
665 dec_mm_counter(mm, anon_rss);
666 #ifdef CONFIG_MIGRATION
669 * Store the pfn of the page in a special migration
670 * pte. do_swap_page() will wait until the migration
671 * pte is removed and then restart fault handling.
674 entry = make_migration_entry(page, pte_write(pteval));
677 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
678 BUG_ON(pte_file(*pte));
680 #ifdef CONFIG_MIGRATION
682 /* Establish migration entry for a file page */
684 entry = make_migration_entry(page, pte_write(pteval));
685 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
688 dec_mm_counter(mm, file_rss);
691 page_remove_rmap(page, vma);
692 page_cache_release(page);
695 pte_unmap_unlock(pte, ptl);
701 * objrmap doesn't work for nonlinear VMAs because the assumption that
702 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
703 * Consequently, given a particular page and its ->index, we cannot locate the
704 * ptes which are mapping that page without an exhaustive linear search.
706 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
707 * maps the file to which the target page belongs. The ->vm_private_data field
708 * holds the current cursor into that scan. Successive searches will circulate
709 * around the vma's virtual address space.
711 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
712 * more scanning pressure is placed against them as well. Eventually pages
713 * will become fully unmapped and are eligible for eviction.
715 * For very sparsely populated VMAs this is a little inefficient - chances are
716 * there there won't be many ptes located within the scan cluster. In this case
717 * maybe we could scan further - to the end of the pte page, perhaps.
719 #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
720 #define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
722 static void try_to_unmap_cluster(unsigned long cursor,
723 unsigned int *mapcount, struct vm_area_struct *vma)
725 struct mm_struct *mm = vma->vm_mm;
733 unsigned long address;
736 address = (vma->vm_start + cursor) & CLUSTER_MASK;
737 end = address + CLUSTER_SIZE;
738 if (address < vma->vm_start)
739 address = vma->vm_start;
740 if (end > vma->vm_end)
743 pgd = pgd_offset(mm, address);
744 if (!pgd_present(*pgd))
747 pud = pud_offset(pgd, address);
748 if (!pud_present(*pud))
751 pmd = pmd_offset(pud, address);
752 if (!pmd_present(*pmd))
755 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
757 /* Update high watermark before we lower rss */
758 update_hiwater_rss(mm);
760 for (; address < end; pte++, address += PAGE_SIZE) {
761 if (!pte_present(*pte))
763 page = vm_normal_page(vma, address, *pte);
764 BUG_ON(!page || PageAnon(page));
766 if (ptep_clear_flush_young(vma, address, pte))
769 /* Nuke the page table entry. */
770 flush_cache_page(vma, address, pte_pfn(*pte));
771 pteval = ptep_clear_flush(vma, address, pte);
773 /* If nonlinear, store the file page offset in the pte. */
774 if (page->index != linear_page_index(vma, address))
775 set_pte_at(mm, address, pte, pgoff_to_pte(page->index));
777 /* Move the dirty bit to the physical page now the pte is gone. */
778 if (pte_dirty(pteval))
779 set_page_dirty(page);
781 page_remove_rmap(page, vma);
782 page_cache_release(page);
783 dec_mm_counter(mm, file_rss);
786 pte_unmap_unlock(pte - 1, ptl);
789 static int try_to_unmap_anon(struct page *page, int migration)
791 struct anon_vma *anon_vma;
792 struct vm_area_struct *vma;
793 int ret = SWAP_AGAIN;
795 anon_vma = page_lock_anon_vma(page);
799 list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
800 ret = try_to_unmap_one(page, vma, migration);
801 if (ret == SWAP_FAIL || !page_mapped(page))
804 spin_unlock(&anon_vma->lock);
809 * try_to_unmap_file - unmap file page using the object-based rmap method
810 * @page: the page to unmap
812 * Find all the mappings of a page using the mapping pointer and the vma chains
813 * contained in the address_space struct it points to.
815 * This function is only called from try_to_unmap for object-based pages.
817 static int try_to_unmap_file(struct page *page, int migration)
819 struct address_space *mapping = page->mapping;
820 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
821 struct vm_area_struct *vma;
822 struct prio_tree_iter iter;
823 int ret = SWAP_AGAIN;
824 unsigned long cursor;
825 unsigned long max_nl_cursor = 0;
826 unsigned long max_nl_size = 0;
827 unsigned int mapcount;
829 spin_lock(&mapping->i_mmap_lock);
830 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
831 ret = try_to_unmap_one(page, vma, migration);
832 if (ret == SWAP_FAIL || !page_mapped(page))
836 if (list_empty(&mapping->i_mmap_nonlinear))
839 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
840 shared.vm_set.list) {
841 if ((vma->vm_flags & VM_LOCKED) && !migration)
843 cursor = (unsigned long) vma->vm_private_data;
844 if (cursor > max_nl_cursor)
845 max_nl_cursor = cursor;
846 cursor = vma->vm_end - vma->vm_start;
847 if (cursor > max_nl_size)
848 max_nl_size = cursor;
851 if (max_nl_size == 0) { /* any nonlinears locked or reserved */
857 * We don't try to search for this page in the nonlinear vmas,
858 * and page_referenced wouldn't have found it anyway. Instead
859 * just walk the nonlinear vmas trying to age and unmap some.
860 * The mapcount of the page we came in with is irrelevant,
861 * but even so use it as a guide to how hard we should try?
863 mapcount = page_mapcount(page);
866 cond_resched_lock(&mapping->i_mmap_lock);
868 max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
869 if (max_nl_cursor == 0)
870 max_nl_cursor = CLUSTER_SIZE;
873 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
874 shared.vm_set.list) {
875 if ((vma->vm_flags & VM_LOCKED) && !migration)
877 cursor = (unsigned long) vma->vm_private_data;
878 while ( cursor < max_nl_cursor &&
879 cursor < vma->vm_end - vma->vm_start) {
880 try_to_unmap_cluster(cursor, &mapcount, vma);
881 cursor += CLUSTER_SIZE;
882 vma->vm_private_data = (void *) cursor;
883 if ((int)mapcount <= 0)
886 vma->vm_private_data = (void *) max_nl_cursor;
888 cond_resched_lock(&mapping->i_mmap_lock);
889 max_nl_cursor += CLUSTER_SIZE;
890 } while (max_nl_cursor <= max_nl_size);
893 * Don't loop forever (perhaps all the remaining pages are
894 * in locked vmas). Reset cursor on all unreserved nonlinear
895 * vmas, now forgetting on which ones it had fallen behind.
897 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
898 vma->vm_private_data = NULL;
900 spin_unlock(&mapping->i_mmap_lock);
905 * try_to_unmap - try to remove all page table mappings to a page
906 * @page: the page to get unmapped
908 * Tries to remove all the page table entries which are mapping this
909 * page, used in the pageout path. Caller must hold the page lock.
912 * SWAP_SUCCESS - we succeeded in removing all mappings
913 * SWAP_AGAIN - we missed a mapping, try again later
914 * SWAP_FAIL - the page is unswappable
916 int try_to_unmap(struct page *page, int migration)
920 BUG_ON(!PageLocked(page));
923 ret = try_to_unmap_anon(page, migration);
925 ret = try_to_unmap_file(page, migration);
927 if (!page_mapped(page))