| /* |
| * linux/mm/swap.c |
| * |
| * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
| */ |
| |
| /* |
| * This file contains the default values for the operation of the |
| * Linux VM subsystem. Fine-tuning documentation can be found in |
| * Documentation/sysctl/vm.txt. |
| * Started 18.12.91 |
| * Swap aging added 23.2.95, Stephen Tweedie. |
| * Buffermem limits added 12.3.98, Rik van Riel. |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/sched.h> |
| #include <linux/kernel_stat.h> |
| #include <linux/swap.h> |
| #include <linux/mman.h> |
| #include <linux/pagemap.h> |
| #include <linux/pagevec.h> |
| #include <linux/init.h> |
| #include <linux/export.h> |
| #include <linux/mm_inline.h> |
| #include <linux/buffer_head.h> /* for try_to_release_page() */ |
| #include <linux/percpu_counter.h> |
| #include <linux/percpu.h> |
| #include <linux/cpu.h> |
| #include <linux/notifier.h> |
| #include <linux/backing-dev.h> |
| #include <linux/memcontrol.h> |
| #include <linux/gfp.h> |
| |
| #include "internal.h" |
| |
| /* How many pages do we try to swap or page in/out together? */ |
| int page_cluster; |
| |
| static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs); |
| static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); |
| static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); |
| |
| /* |
| * This path almost never happens for VM activity - pages are normally |
| * freed via pagevecs. But it gets used by networking. |
| */ |
| static void __page_cache_release(struct page *page) |
| { |
| if (PageLRU(page)) { |
| unsigned long flags; |
| struct zone *zone = page_zone(page); |
| |
| spin_lock_irqsave(&zone->lru_lock, flags); |
| VM_BUG_ON(!PageLRU(page)); |
| __ClearPageLRU(page); |
| del_page_from_lru(zone, page); |
| spin_unlock_irqrestore(&zone->lru_lock, flags); |
| } |
| } |
| |
| static void __put_single_page(struct page *page) |
| { |
| __page_cache_release(page); |
| free_hot_cold_page(page, 0); |
| } |
| |
| static void __put_compound_page(struct page *page) |
| { |
| compound_page_dtor *dtor; |
| |
| __page_cache_release(page); |
| dtor = get_compound_page_dtor(page); |
| (*dtor)(page); |
| } |
| |
| static void put_compound_page(struct page *page) |
| { |
| if (unlikely(PageTail(page))) { |
| /* __split_huge_page_refcount can run under us */ |
| struct page *page_head = compound_trans_head(page); |
| |
| if (likely(page != page_head && |
| get_page_unless_zero(page_head))) { |
| unsigned long flags; |
| /* |
| * page_head wasn't a dangling pointer but it |
| * may not be a head page anymore by the time |
| * we obtain the lock. That is ok as long as it |
| * can't be freed from under us. |
| */ |
| flags = compound_lock_irqsave(page_head); |
| if (unlikely(!PageTail(page))) { |
| /* __split_huge_page_refcount run before us */ |
| compound_unlock_irqrestore(page_head, flags); |
| VM_BUG_ON(PageHead(page_head)); |
| if (put_page_testzero(page_head)) |
| __put_single_page(page_head); |
| out_put_single: |
| if (put_page_testzero(page)) |
| __put_single_page(page); |
| return; |
| } |
| VM_BUG_ON(page_head != page->first_page); |
| /* |
| * We can release the refcount taken by |
| * get_page_unless_zero() now that |
| * __split_huge_page_refcount() is blocked on |
| * the compound_lock. |
| */ |
| if (put_page_testzero(page_head)) |
| VM_BUG_ON(1); |
| /* __split_huge_page_refcount will wait now */ |
| VM_BUG_ON(page_mapcount(page) <= 0); |
| atomic_dec(&page->_mapcount); |
| VM_BUG_ON(atomic_read(&page_head->_count) <= 0); |
| VM_BUG_ON(atomic_read(&page->_count) != 0); |
| compound_unlock_irqrestore(page_head, flags); |
| if (put_page_testzero(page_head)) { |
| if (PageHead(page_head)) |
| __put_compound_page(page_head); |
| else |
| __put_single_page(page_head); |
| } |
| } else { |
| /* page_head is a dangling pointer */ |
| VM_BUG_ON(PageTail(page)); |
| goto out_put_single; |
| } |
| } else if (put_page_testzero(page)) { |
| if (PageHead(page)) |
| __put_compound_page(page); |
| else |
| __put_single_page(page); |
| } |
| } |
| |
| void put_page(struct page *page) |
| { |
| if (unlikely(PageCompound(page))) |
| put_compound_page(page); |
| else if (put_page_testzero(page)) |
| __put_single_page(page); |
| } |
| EXPORT_SYMBOL(put_page); |
| |
| /* |
| * This function is exported but must not be called by anything other |
| * than get_page(). It implements the slow path of get_page(). |
| */ |
| bool __get_page_tail(struct page *page) |
| { |
| /* |
| * This takes care of get_page() if run on a tail page |
| * returned by one of the get_user_pages/follow_page variants. |
| * get_user_pages/follow_page itself doesn't need the compound |
| * lock because it runs __get_page_tail_foll() under the |
| * proper PT lock that already serializes against |
| * split_huge_page(). |
| */ |
| unsigned long flags; |
| bool got = false; |
| struct page *page_head = compound_trans_head(page); |
| |
| if (likely(page != page_head && get_page_unless_zero(page_head))) { |
| /* |
| * page_head wasn't a dangling pointer but it |
| * may not be a head page anymore by the time |
| * we obtain the lock. That is ok as long as it |
| * can't be freed from under us. |
| */ |
| flags = compound_lock_irqsave(page_head); |
| /* here __split_huge_page_refcount won't run anymore */ |
| if (likely(PageTail(page))) { |
| __get_page_tail_foll(page, false); |
| got = true; |
| } |
| compound_unlock_irqrestore(page_head, flags); |
| if (unlikely(!got)) |
| put_page(page_head); |
| } |
| return got; |
| } |
| EXPORT_SYMBOL(__get_page_tail); |
| |
| /** |
| * put_pages_list() - release a list of pages |
| * @pages: list of pages threaded on page->lru |
| * |
| * Release a list of pages which are strung together on page.lru. Currently |
| * used by read_cache_pages() and related error recovery code. |
| */ |
| void put_pages_list(struct list_head *pages) |
| { |
| while (!list_empty(pages)) { |
| struct page *victim; |
| |
| victim = list_entry(pages->prev, struct page, lru); |
| list_del(&victim->lru); |
| page_cache_release(victim); |
| } |
| } |
| EXPORT_SYMBOL(put_pages_list); |
| |
| static void pagevec_lru_move_fn(struct pagevec *pvec, |
| void (*move_fn)(struct page *page, void *arg), |
| void *arg) |
| { |
| int i; |
| struct zone *zone = NULL; |
| unsigned long flags = 0; |
| |
| for (i = 0; i < pagevec_count(pvec); i++) { |
| struct page *page = pvec->pages[i]; |
| struct zone *pagezone = page_zone(page); |
| |
| if (pagezone != zone) { |
| if (zone) |
| spin_unlock_irqrestore(&zone->lru_lock, flags); |
| zone = pagezone; |
| spin_lock_irqsave(&zone->lru_lock, flags); |
| } |
| |
| (*move_fn)(page, arg); |
| } |
| if (zone) |
| spin_unlock_irqrestore(&zone->lru_lock, flags); |
| release_pages(pvec->pages, pvec->nr, pvec->cold); |
| pagevec_reinit(pvec); |
| } |
| |
| static void pagevec_move_tail_fn(struct page *page, void *arg) |
| { |
| int *pgmoved = arg; |
| struct zone *zone = page_zone(page); |
| |
| if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
| enum lru_list lru = page_lru_base_type(page); |
| list_move_tail(&page->lru, &zone->lru[lru].list); |
| mem_cgroup_rotate_reclaimable_page(page); |
| (*pgmoved)++; |
| } |
| } |
| |
| /* |
| * pagevec_move_tail() must be called with IRQ disabled. |
| * Otherwise this may cause nasty races. |
| */ |
| static void pagevec_move_tail(struct pagevec *pvec) |
| { |
| int pgmoved = 0; |
| |
| pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved); |
| __count_vm_events(PGROTATED, pgmoved); |
| } |
| |
| /* |
| * Writeback is about to end against a page which has been marked for immediate |
| * reclaim. If it still appears to be reclaimable, move it to the tail of the |
| * inactive list. |
| */ |
| void rotate_reclaimable_page(struct page *page) |
| { |
| if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) && |
| !PageUnevictable(page) && PageLRU(page)) { |
| struct pagevec *pvec; |
| unsigned long flags; |
| |
| page_cache_get(page); |
| local_irq_save(flags); |
| pvec = &__get_cpu_var(lru_rotate_pvecs); |
| if (!pagevec_add(pvec, page)) |
| pagevec_move_tail(pvec); |
| local_irq_restore(flags); |
| } |
| } |
| |
| static void update_page_reclaim_stat(struct zone *zone, struct page *page, |
| int file, int rotated) |
| { |
| struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat; |
| struct zone_reclaim_stat *memcg_reclaim_stat; |
| |
| memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page); |
| |
| reclaim_stat->recent_scanned[file]++; |
| if (rotated) |
| reclaim_stat->recent_rotated[file]++; |
| |
| if (!memcg_reclaim_stat) |
| return; |
| |
| memcg_reclaim_stat->recent_scanned[file]++; |
| if (rotated) |
| memcg_reclaim_stat->recent_rotated[file]++; |
| } |
| |
| static void __activate_page(struct page *page, void *arg) |
| { |
| struct zone *zone = page_zone(page); |
| |
| if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
| int file = page_is_file_cache(page); |
| int lru = page_lru_base_type(page); |
| del_page_from_lru_list(zone, page, lru); |
| |
| SetPageActive(page); |
| lru += LRU_ACTIVE; |
| add_page_to_lru_list(zone, page, lru); |
| __count_vm_event(PGACTIVATE); |
| |
| update_page_reclaim_stat(zone, page, file, 1); |
| } |
| } |
| |
| #ifdef CONFIG_SMP |
| static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs); |
| |
| static void activate_page_drain(int cpu) |
| { |
| struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu); |
| |
| if (pagevec_count(pvec)) |
| pagevec_lru_move_fn(pvec, __activate_page, NULL); |
| } |
| |
| void activate_page(struct page *page) |
| { |
| if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { |
| struct pagevec *pvec = &get_cpu_var(activate_page_pvecs); |
| |
| page_cache_get(page); |
| if (!pagevec_add(pvec, page)) |
| pagevec_lru_move_fn(pvec, __activate_page, NULL); |
| put_cpu_var(activate_page_pvecs); |
| } |
| } |
| |
| #else |
| static inline void activate_page_drain(int cpu) |
| { |
| } |
| |
| void activate_page(struct page *page) |
| { |
| struct zone *zone = page_zone(page); |
| |
| spin_lock_irq(&zone->lru_lock); |
| __activate_page(page, NULL); |
| spin_unlock_irq(&zone->lru_lock); |
| } |
| #endif |
| |
| /* |
| * Mark a page as having seen activity. |
| * |
| * inactive,unreferenced -> inactive,referenced |
| * inactive,referenced -> active,unreferenced |
| * active,unreferenced -> active,referenced |
| */ |
| void mark_page_accessed(struct page *page) |
| { |
| if (!PageActive(page) && !PageUnevictable(page) && |
| PageReferenced(page) && PageLRU(page)) { |
| activate_page(page); |
| ClearPageReferenced(page); |
| } else if (!PageReferenced(page)) { |
| SetPageReferenced(page); |
| } |
| } |
| |
| EXPORT_SYMBOL(mark_page_accessed); |
| |
| void __lru_cache_add(struct page *page, enum lru_list lru) |
| { |
| struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru]; |
| |
| page_cache_get(page); |
| if (!pagevec_add(pvec, page)) |
| ____pagevec_lru_add(pvec, lru); |
| put_cpu_var(lru_add_pvecs); |
| } |
| EXPORT_SYMBOL(__lru_cache_add); |
| |
| /** |
| * lru_cache_add_lru - add a page to a page list |
| * @page: the page to be added to the LRU. |
| * @lru: the LRU list to which the page is added. |
| */ |
| void lru_cache_add_lru(struct page *page, enum lru_list lru) |
| { |
| if (PageActive(page)) { |
| VM_BUG_ON(PageUnevictable(page)); |
| ClearPageActive(page); |
| } else if (PageUnevictable(page)) { |
| VM_BUG_ON(PageActive(page)); |
| ClearPageUnevictable(page); |
| } |
| |
| VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page)); |
| __lru_cache_add(page, lru); |
| } |
| |
| /** |
| * add_page_to_unevictable_list - add a page to the unevictable list |
| * @page: the page to be added to the unevictable list |
| * |
| * Add page directly to its zone's unevictable list. To avoid races with |
| * tasks that might be making the page evictable, through eg. munlock, |
| * munmap or exit, while it's not on the lru, we want to add the page |
| * while it's locked or otherwise "invisible" to other tasks. This is |
| * difficult to do when using the pagevec cache, so bypass that. |
| */ |
| void add_page_to_unevictable_list(struct page *page) |
| { |
| struct zone *zone = page_zone(page); |
| |
| spin_lock_irq(&zone->lru_lock); |
| SetPageUnevictable(page); |
| SetPageLRU(page); |
| add_page_to_lru_list(zone, page, LRU_UNEVICTABLE); |
| spin_unlock_irq(&zone->lru_lock); |
| } |
| |
| /* |
| * If the page can not be invalidated, it is moved to the |
| * inactive list to speed up its reclaim. It is moved to the |
| * head of the list, rather than the tail, to give the flusher |
| * threads some time to write it out, as this is much more |
| * effective than the single-page writeout from reclaim. |
| * |
| * If the page isn't page_mapped and dirty/writeback, the page |
| * could reclaim asap using PG_reclaim. |
| * |
| * 1. active, mapped page -> none |
| * 2. active, dirty/writeback page -> inactive, head, PG_reclaim |
| * 3. inactive, mapped page -> none |
| * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim |
| * 5. inactive, clean -> inactive, tail |
| * 6. Others -> none |
| * |
| * In 4, why it moves inactive's head, the VM expects the page would |
| * be write it out by flusher threads as this is much more effective |
| * than the single-page writeout from reclaim. |
| */ |
| static void lru_deactivate_fn(struct page *page, void *arg) |
| { |
| int lru, file; |
| bool active; |
| struct zone *zone = page_zone(page); |
| |
| if (!PageLRU(page)) |
| return; |
| |
| if (PageUnevictable(page)) |
| return; |
| |
| /* Some processes are using the page */ |
| if (page_mapped(page)) |
| return; |
| |
| active = PageActive(page); |
| |
| file = page_is_file_cache(page); |
| lru = page_lru_base_type(page); |
| del_page_from_lru_list(zone, page, lru + active); |
| ClearPageActive(page); |
| ClearPageReferenced(page); |
| add_page_to_lru_list(zone, page, lru); |
| |
| if (PageWriteback(page) || PageDirty(page)) { |
| /* |
| * PG_reclaim could be raced with end_page_writeback |
| * It can make readahead confusing. But race window |
| * is _really_ small and it's non-critical problem. |
| */ |
| SetPageReclaim(page); |
| } else { |
| /* |
| * The page's writeback ends up during pagevec |
| * We moves tha page into tail of inactive. |
| */ |
| list_move_tail(&page->lru, &zone->lru[lru].list); |
| mem_cgroup_rotate_reclaimable_page(page); |
| __count_vm_event(PGROTATED); |
| } |
| |
| if (active) |
| __count_vm_event(PGDEACTIVATE); |
| update_page_reclaim_stat(zone, page, file, 0); |
| } |
| |
| /* |
| * Drain pages out of the cpu's pagevecs. |
| * Either "cpu" is the current CPU, and preemption has already been |
| * disabled; or "cpu" is being hot-unplugged, and is already dead. |
| */ |
| static void drain_cpu_pagevecs(int cpu) |
| { |
| struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu); |
| struct pagevec *pvec; |
| int lru; |
| |
| for_each_lru(lru) { |
| pvec = &pvecs[lru - LRU_BASE]; |
| if (pagevec_count(pvec)) |
| ____pagevec_lru_add(pvec, lru); |
| } |
| |
| pvec = &per_cpu(lru_rotate_pvecs, cpu); |
| if (pagevec_count(pvec)) { |
| unsigned long flags; |
| |
| /* No harm done if a racing interrupt already did this */ |
| local_irq_save(flags); |
| pagevec_move_tail(pvec); |
| local_irq_restore(flags); |
| } |
| |
| pvec = &per_cpu(lru_deactivate_pvecs, cpu); |
| if (pagevec_count(pvec)) |
| pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); |
| |
| activate_page_drain(cpu); |
| } |
| |
| /** |
| * deactivate_page - forcefully deactivate a page |
| * @page: page to deactivate |
| * |
| * This function hints the VM that @page is a good reclaim candidate, |
| * for example if its invalidation fails due to the page being dirty |
| * or under writeback. |
| */ |
| void deactivate_page(struct page *page) |
| { |
| /* |
| * In a workload with many unevictable page such as mprotect, unevictable |
| * page deactivation for accelerating reclaim is pointless. |
| */ |
| if (PageUnevictable(page)) |
| return; |
| |
| if (likely(get_page_unless_zero(page))) { |
| struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs); |
| |
| if (!pagevec_add(pvec, page)) |
| pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); |
| put_cpu_var(lru_deactivate_pvecs); |
| } |
| } |
| |
| void lru_add_drain(void) |
| { |
| drain_cpu_pagevecs(get_cpu()); |
| put_cpu(); |
| } |
| |
| static void lru_add_drain_per_cpu(struct work_struct *dummy) |
| { |
| lru_add_drain(); |
| } |
| |
| /* |
| * Returns 0 for success |
| */ |
| int lru_add_drain_all(void) |
| { |
| return schedule_on_each_cpu(lru_add_drain_per_cpu); |
| } |
| |
| /* |
| * Batched page_cache_release(). Decrement the reference count on all the |
| * passed pages. If it fell to zero then remove the page from the LRU and |
| * free it. |
| * |
| * Avoid taking zone->lru_lock if possible, but if it is taken, retain it |
| * for the remainder of the operation. |
| * |
| * The locking in this function is against shrink_inactive_list(): we recheck |
| * the page count inside the lock to see whether shrink_inactive_list() |
| * grabbed the page via the LRU. If it did, give up: shrink_inactive_list() |
| * will free it. |
| */ |
| void release_pages(struct page **pages, int nr, int cold) |
| { |
| int i; |
| LIST_HEAD(pages_to_free); |
| struct zone *zone = NULL; |
| unsigned long uninitialized_var(flags); |
| |
| for (i = 0; i < nr; i++) { |
| struct page *page = pages[i]; |
| |
| if (unlikely(PageCompound(page))) { |
| if (zone) { |
| spin_unlock_irqrestore(&zone->lru_lock, flags); |
| zone = NULL; |
| } |
| put_compound_page(page); |
| continue; |
| } |
| |
| if (!put_page_testzero(page)) |
| continue; |
| |
| if (PageLRU(page)) { |
| struct zone *pagezone = page_zone(page); |
| |
| if (pagezone != zone) { |
| if (zone) |
| spin_unlock_irqrestore(&zone->lru_lock, |
| flags); |
| zone = pagezone; |
| spin_lock_irqsave(&zone->lru_lock, flags); |
| } |
| VM_BUG_ON(!PageLRU(page)); |
| __ClearPageLRU(page); |
| del_page_from_lru(zone, page); |
| } |
| |
| list_add(&page->lru, &pages_to_free); |
| } |
| if (zone) |
| spin_unlock_irqrestore(&zone->lru_lock, flags); |
| |
| free_hot_cold_page_list(&pages_to_free, cold); |
| } |
| EXPORT_SYMBOL(release_pages); |
| |
| /* |
| * The pages which we're about to release may be in the deferred lru-addition |
| * queues. That would prevent them from really being freed right now. That's |
| * OK from a correctness point of view but is inefficient - those pages may be |
| * cache-warm and we want to give them back to the page allocator ASAP. |
| * |
| * So __pagevec_release() will drain those queues here. __pagevec_lru_add() |
| * and __pagevec_lru_add_active() call release_pages() directly to avoid |
| * mutual recursion. |
| */ |
| void __pagevec_release(struct pagevec *pvec) |
| { |
| lru_add_drain(); |
| release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); |
| pagevec_reinit(pvec); |
| } |
| |
| EXPORT_SYMBOL(__pagevec_release); |
| |
| /* used by __split_huge_page_refcount() */ |
| void lru_add_page_tail(struct zone* zone, |
| struct page *page, struct page *page_tail) |
| { |
| int active; |
| enum lru_list lru; |
| const int file = 0; |
| struct list_head *head; |
| |
| VM_BUG_ON(!PageHead(page)); |
| VM_BUG_ON(PageCompound(page_tail)); |
| VM_BUG_ON(PageLRU(page_tail)); |
| VM_BUG_ON(!spin_is_locked(&zone->lru_lock)); |
| |
| SetPageLRU(page_tail); |
| |
| if (page_evictable(page_tail, NULL)) { |
| if (PageActive(page)) { |
| SetPageActive(page_tail); |
| active = 1; |
| lru = LRU_ACTIVE_ANON; |
| } else { |
| active = 0; |
| lru = LRU_INACTIVE_ANON; |
| } |
| update_page_reclaim_stat(zone, page_tail, file, active); |
| if (likely(PageLRU(page))) |
| head = page->lru.prev; |
| else |
| head = &zone->lru[lru].list; |
| __add_page_to_lru_list(zone, page_tail, lru, head); |
| } else { |
| SetPageUnevictable(page_tail); |
| add_page_to_lru_list(zone, page_tail, LRU_UNEVICTABLE); |
| } |
| } |
| |
| static void ____pagevec_lru_add_fn(struct page *page, void *arg) |
| { |
| enum lru_list lru = (enum lru_list)arg; |
| struct zone *zone = page_zone(page); |
| int file = is_file_lru(lru); |
| int active = is_active_lru(lru); |
| |
| VM_BUG_ON(PageActive(page)); |
| VM_BUG_ON(PageUnevictable(page)); |
| VM_BUG_ON(PageLRU(page)); |
| |
| SetPageLRU(page); |
| if (active) |
| SetPageActive(page); |
| update_page_reclaim_stat(zone, page, file, active); |
| add_page_to_lru_list(zone, page, lru); |
| } |
| |
| /* |
| * Add the passed pages to the LRU, then drop the caller's refcount |
| * on them. Reinitialises the caller's pagevec. |
| */ |
| void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru) |
| { |
| VM_BUG_ON(is_unevictable_lru(lru)); |
| |
| pagevec_lru_move_fn(pvec, ____pagevec_lru_add_fn, (void *)lru); |
| } |
| |
| EXPORT_SYMBOL(____pagevec_lru_add); |
| |
| /* |
| * Try to drop buffers from the pages in a pagevec |
| */ |
| void pagevec_strip(struct pagevec *pvec) |
| { |
| int i; |
| |
| for (i = 0; i < pagevec_count(pvec); i++) { |
| struct page *page = pvec->pages[i]; |
| |
| if (page_has_private(page) && trylock_page(page)) { |
| if (page_has_private(page)) |
| try_to_release_page(page, 0); |
| unlock_page(page); |
| } |
| } |
| } |
| |
| /** |
| * pagevec_lookup - gang pagecache lookup |
| * @pvec: Where the resulting pages are placed |
| * @mapping: The address_space to search |
| * @start: The starting page index |
| * @nr_pages: The maximum number of pages |
| * |
| * pagevec_lookup() will search for and return a group of up to @nr_pages pages |
| * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a |
| * reference against the pages in @pvec. |
| * |
| * The search returns a group of mapping-contiguous pages with ascending |
| * indexes. There may be holes in the indices due to not-present pages. |
| * |
| * pagevec_lookup() returns the number of pages which were found. |
| */ |
| unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, |
| pgoff_t start, unsigned nr_pages) |
| { |
| pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); |
| return pagevec_count(pvec); |
| } |
| |
| EXPORT_SYMBOL(pagevec_lookup); |
| |
| unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, |
| pgoff_t *index, int tag, unsigned nr_pages) |
| { |
| pvec->nr = find_get_pages_tag(mapping, index, tag, |
| nr_pages, pvec->pages); |
| return pagevec_count(pvec); |
| } |
| |
| EXPORT_SYMBOL(pagevec_lookup_tag); |
| |
| /* |
| * Perform any setup for the swap system |
| */ |
| void __init swap_setup(void) |
| { |
| unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT); |
| |
| #ifdef CONFIG_SWAP |
| bdi_init(swapper_space.backing_dev_info); |
| #endif |
| |
| /* Use a smaller cluster for small-memory machines */ |
| if (megs < 16) |
| page_cluster = 2; |
| else |
| page_cluster = 3; |
| /* |
| * Right now other parts of the system means that we |
| * _really_ don't want to cluster much more |
| */ |
| } |