diff options
Diffstat (limited to 'mm/vmscan.c')
| -rw-r--r-- | mm/vmscan.c | 1026 |
1 files changed, 760 insertions, 266 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index 1ff1a58e7c10..3b5860294bb6 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -39,6 +39,7 @@ #include <linux/freezer.h> #include <linux/memcontrol.h> #include <linux/delayacct.h> +#include <linux/sysctl.h> #include <asm/tlbflush.h> #include <asm/div64.h> @@ -78,7 +79,7 @@ struct scan_control { unsigned long (*isolate_pages)(unsigned long nr, struct list_head *dst, unsigned long *scanned, int order, int mode, struct zone *z, struct mem_cgroup *mem_cont, - int active); + int active, int file); }; #define lru_to_page(_head) (list_entry((_head)->prev, struct page, lru)) @@ -470,6 +471,85 @@ int remove_mapping(struct address_space *mapping, struct page *page) return 0; } +/** + * putback_lru_page - put previously isolated page onto appropriate LRU list + * @page: page to be put back to appropriate lru list + * + * Add previously isolated @page to appropriate LRU list. + * Page may still be unevictable for other reasons. + * + * lru_lock must not be held, interrupts must be enabled. + */ +#ifdef CONFIG_UNEVICTABLE_LRU +void putback_lru_page(struct page *page) +{ + int lru; + int active = !!TestClearPageActive(page); + int was_unevictable = PageUnevictable(page); + + VM_BUG_ON(PageLRU(page)); + +redo: + ClearPageUnevictable(page); + + if (page_evictable(page, NULL)) { + /* + * For evictable pages, we can use the cache. + * In event of a race, worst case is we end up with an + * unevictable page on [in]active list. + * We know how to handle that. + */ + lru = active + page_is_file_cache(page); + lru_cache_add_lru(page, lru); + } else { + /* + * Put unevictable pages directly on zone's unevictable + * list. + */ + lru = LRU_UNEVICTABLE; + add_page_to_unevictable_list(page); + } + mem_cgroup_move_lists(page, lru); + + /* + * page's status can change while we move it among lru. If an evictable + * page is on unevictable list, it never be freed. To avoid that, + * check after we added it to the list, again. + */ + if (lru == LRU_UNEVICTABLE && page_evictable(page, NULL)) { + if (!isolate_lru_page(page)) { + put_page(page); + goto redo; + } + /* This means someone else dropped this page from LRU + * So, it will be freed or putback to LRU again. There is + * nothing to do here. + */ + } + + if (was_unevictable && lru != LRU_UNEVICTABLE) + count_vm_event(UNEVICTABLE_PGRESCUED); + else if (!was_unevictable && lru == LRU_UNEVICTABLE) + count_vm_event(UNEVICTABLE_PGCULLED); + + put_page(page); /* drop ref from isolate */ +} + +#else /* CONFIG_UNEVICTABLE_LRU */ + +void putback_lru_page(struct page *page) +{ + int lru; + VM_BUG_ON(PageLRU(page)); + + lru = !!TestClearPageActive(page) + page_is_file_cache(page); + lru_cache_add_lru(page, lru); + mem_cgroup_move_lists(page, lru); + put_page(page); +} +#endif /* CONFIG_UNEVICTABLE_LRU */ + + /* * shrink_page_list() returns the number of reclaimed pages */ @@ -503,6 +583,9 @@ static unsigned long shrink_page_list(struct list_head *page_list, sc->nr_scanned++; + if (unlikely(!page_evictable(page, NULL))) + goto cull_mlocked; + if (!sc->may_swap && page_mapped(page)) goto keep_locked; @@ -539,9 +622,19 @@ static unsigned long shrink_page_list(struct list_head *page_list, * Anonymous process memory has backing store? * Try to allocate it some swap space here. */ - if (PageAnon(page) && !PageSwapCache(page)) + if (PageAnon(page) && !PageSwapCache(page)) { + switch (try_to_munlock(page)) { + case SWAP_FAIL: /* shouldn't happen */ + case SWAP_AGAIN: + goto keep_locked; + case SWAP_MLOCK: + goto cull_mlocked; + case SWAP_SUCCESS: + ; /* fall thru'; add to swap cache */ + } if (!add_to_swap(page, GFP_ATOMIC)) goto activate_locked; + } #endif /* CONFIG_SWAP */ mapping = page_mapping(page); @@ -556,6 +649,8 @@ static unsigned long shrink_page_list(struct list_head *page_list, goto activate_locked; case SWAP_AGAIN: goto keep_locked; + case SWAP_MLOCK: + goto cull_mlocked; case SWAP_SUCCESS: ; /* try to free the page below */ } @@ -602,7 +697,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, * possible for a page to have PageDirty set, but it is actually * clean (all its buffers are clean). This happens if the * buffers were written out directly, with submit_bh(). ext3 - * will do this, as well as the blockdev mapping. + * will do this, as well as the blockdev mapping. * try_to_release_page() will discover that cleanness and will * drop the buffers and mark the page clean - it can be freed. * @@ -637,7 +732,14 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (!mapping || !__remove_mapping(mapping, page)) goto keep_locked; - unlock_page(page); + /* + * At this point, we have no other references and there is + * no way to pick any more up (removed from LRU, removed + * from pagecache). Can use non-atomic bitops now (and + * we obviously don't have to worry about waking up a process + * waiting on the page lock, because there are no references. + */ + __clear_page_locked(page); free_it: nr_reclaimed++; if (!pagevec_add(&freed_pvec, page)) { @@ -646,14 +748,23 @@ free_it: } continue; +cull_mlocked: + unlock_page(page); + putback_lru_page(page); + continue; + activate_locked: + /* Not a candidate for swapping, so reclaim swap space. */ + if (PageSwapCache(page) && vm_swap_full()) + remove_exclusive_swap_page_ref(page); + VM_BUG_ON(PageActive(page)); SetPageActive(page); pgactivate++; keep_locked: unlock_page(page); keep: list_add(&page->lru, &ret_pages); - VM_BUG_ON(PageLRU(page)); + VM_BUG_ON(PageLRU(page) || PageUnevictable(page)); } list_splice(&ret_pages, page_list); if (pagevec_count(&freed_pvec)) @@ -677,7 +788,7 @@ keep: * * returns 0 on success, -ve errno on failure. */ -int __isolate_lru_page(struct page *page, int mode) +int __isolate_lru_page(struct page *page, int mode, int file) { int ret = -EINVAL; @@ -693,6 +804,17 @@ int __isolate_lru_page(struct page *page, int mode) if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode)) return ret; + if (mode != ISOLATE_BOTH && (!page_is_file_cache(page) != !file)) + return ret; + + /* + * When this function is being called for lumpy reclaim, we + * initially look into all LRU pages, active, inactive and + * unevictable; only give shrink_page_list evictable pages. + */ + if (PageUnevictable(page)) + return ret; + ret = -EBUSY; if (likely(get_page_unless_zero(page))) { /* @@ -723,12 +845,13 @@ int __isolate_lru_page(struct page *page, int mode) * @scanned: The number of pages that were scanned. * @order: The caller's attempted allocation order * @mode: One of the LRU isolation modes + * @file: True [1] if isolating file [!anon] pages * * returns how many pages were moved onto *@dst. */ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, struct list_head *src, struct list_head *dst, - unsigned long *scanned, int order, int mode) + unsigned long *scanned, int order, int mode, int file) { unsigned long nr_taken = 0; unsigned long scan; @@ -745,7 +868,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, VM_BUG_ON(!PageLRU(page)); - switch (__isolate_lru_page(page, mode)) { + switch (__isolate_lru_page(page, mode, file)) { case 0: list_move(&page->lru, dst); nr_taken++; @@ -788,10 +911,11 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, break; cursor_page = pfn_to_page(pfn); + /* Check that we have not crossed a zone boundary. */ if (unlikely(page_zone_id(cursor_page) != zone_id)) continue; - switch (__isolate_lru_page(cursor_page, mode)) { + switch (__isolate_lru_page(cursor_page, mode, file)) { case 0: list_move(&cursor_page->lru, dst); nr_taken++; @@ -802,7 +926,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, /* else it is being freed elsewhere */ list_move(&cursor_page->lru, src); default: - break; + break; /* ! on LRU or wrong list */ } } } @@ -816,40 +940,93 @@ static unsigned long isolate_pages_global(unsigned long nr, unsigned long *scanned, int order, int mode, struct zone *z, struct mem_cgroup *mem_cont, - int active) + int active, int file) { + int lru = LRU_BASE; if (active) - return isolate_lru_pages(nr, &z->active_list, dst, - scanned, order, mode); - else - return isolate_lru_pages(nr, &z->inactive_list, dst, - scanned, order, mode); + lru += LRU_ACTIVE; + if (file) + lru += LRU_FILE; + return isolate_lru_pages(nr, &z->lru[lru].list, dst, scanned, order, + mode, !!file); } /* * clear_active_flags() is a helper for shrink_active_list(), clearing * any active bits from the pages in the list. */ -static unsigned long clear_active_flags(struct list_head *page_list) +static unsigned long clear_active_flags(struct list_head *page_list, + unsigned int *count) { int nr_active = 0; + int lru; struct page *page; - list_for_each_entry(page, page_list, lru) + list_for_each_entry(page, page_list, lru) { + lru = page_is_file_cache(page); if (PageActive(page)) { + lru += LRU_ACTIVE; ClearPageActive(page); nr_active++; } + count[lru]++; + } return nr_active; } +/** + * isolate_lru_page - tries to isolate a page from its LRU list + * @page: page to isolate from its LRU list + * + * Isolates a @page from an LRU list, clears PageLRU and adjusts the + * vmstat statistic corresponding to whatever LRU list the page was on. + * + * Returns 0 if the page was removed from an LRU list. + * Returns -EBUSY if the page was not on an LRU list. + * + * The returned page will have PageLRU() cleared. If it was found on + * the active list, it will have PageActive set. If it was found on + * the unevictable list, it will have the PageUnevictable bit set. That flag + * may need to be cleared by the caller before letting the page go. + * + * The vmstat statistic corresponding to the list on which the page was + * found will be decremented. + * + * Restrictions: + * (1) Must be called with an elevated refcount on the page. This is a + * fundamentnal difference from isolate_lru_pages (which is called + * without a stable reference). + * (2) the lru_lock must not be held. + * (3) interrupts must be enabled. + */ +int isolate_lru_page(struct page *page) +{ + int ret = -EBUSY; + + if (PageLRU(page)) { + struct zone *zone = page_zone(page); + + spin_lock_irq(&zone->lru_lock); + if (PageLRU(page) && get_page_unless_zero(page)) { + int lru = page_lru(page); + ret = 0; + ClearPageLRU(page); + + del_page_from_lru_list(zone, page, lru); + } + spin_unlock_irq(&zone->lru_lock); + } + return ret; +} + /* * shrink_inactive_list() is a helper for shrink_zone(). It returns the number * of reclaimed pages */ static unsigned long shrink_inactive_list(unsigned long max_scan, - struct zone *zone, struct scan_control *sc) + struct zone *zone, struct scan_control *sc, + int priority, int file) { LIST_HEAD(page_list); struct pagevec pvec; @@ -866,20 +1043,43 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, unsigned long nr_scan; unsigned long nr_freed; unsigned long nr_active; + unsigned int count[NR_LRU_LISTS] = { 0, }; + int mode = ISOLATE_INACTIVE; + + /* + * If we need a large contiguous chunk of memory, or have + * trouble getting a small set of contiguous pages, we + * will reclaim both active and inactive pages. + * + * We use the same threshold as pageout congestion_wait below. + */ + if (sc->order > PAGE_ALLOC_COSTLY_ORDER) + mode = ISOLATE_BOTH; + else if (sc->order && priority < DEF_PRIORITY - 2) + mode = ISOLATE_BOTH; nr_taken = sc->isolate_pages(sc->swap_cluster_max, - &page_list, &nr_scan, sc->order, - (sc->order > PAGE_ALLOC_COSTLY_ORDER)? - ISOLATE_BOTH : ISOLATE_INACTIVE, - zone, sc->mem_cgroup, 0); - nr_active = clear_active_flags(&page_list); + &page_list, &nr_scan, sc->order, mode, + zone, sc->mem_cgroup, 0, file); + nr_active = clear_active_flags(&page_list, count); __count_vm_events(PGDEACTIVATE, nr_active); - __mod_zone_page_state(zone, NR_ACTIVE, -nr_active); - __mod_zone_page_state(zone, NR_INACTIVE, - -(nr_taken - nr_active)); - if (scan_global_lru(sc)) + __mod_zone_page_state(zone, NR_ACTIVE_FILE, + -count[LRU_ACTIVE_FILE]); + __mod_zone_page_state(zone, NR_INACTIVE_FILE, + -count[LRU_INACTIVE_FILE]); + __mod_zone_page_state(zone, NR_ACTIVE_ANON, + -count[LRU_ACTIVE_ANON]); + __mod_zone_page_state(zone, NR_INACTIVE_ANON, + -count[LRU_INACTIVE_ANON]); + + if (scan_global_lru(sc)) { zone->pages_scanned += nr_scan; + zone->recent_scanned[0] += count[LRU_INACTIVE_ANON]; + zone->recent_scanned[0] += count[LRU_ACTIVE_ANON]; + zone->recent_scanned[1] += count[LRU_INACTIVE_FILE]; + zone->recent_scanned[1] += count[LRU_ACTIVE_FILE]; + } spin_unlock_irq(&zone->lru_lock); nr_scanned += nr_scan; @@ -899,7 +1099,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, * The attempt at page out may have made some * of the pages active, mark them inactive again. */ - nr_active = clear_active_flags(&page_list); + nr_active = clear_active_flags(&page_list, count); count_vm_events(PGDEACTIVATE, nr_active); nr_freed += shrink_page_list(&page_list, sc, @@ -924,14 +1124,24 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, * Put back any unfreeable pages. */ while (!list_empty(&page_list)) { + int lru; page = lru_to_page(&page_list); VM_BUG_ON(PageLRU(page)); - SetPageLRU(page); list_del(&page->lru); - if (PageActive(page)) - add_page_to_active_list(zone, page); - else - add_page_to_inactive_list(zone, page); + if (unlikely(!page_evictable(page, NULL))) { + spin_unlock_irq(&zone->lru_lock); + putback_lru_page(page); + spin_lock_irq(&zone->lru_lock); + continue; + } + SetPageLRU(page); + lru = page_lru(page); + add_page_to_lru_list(zone, page, lru); + mem_cgroup_move_lists(page, lru); + if (PageActive(page) && scan_global_lru(sc)) { + int file = !!page_is_file_cache(page); + zone->recent_rotated[file]++; + } if (!pagevec_add(&pvec, page)) { spin_unlock_irq(&zone->lru_lock); __pagevec_release(&pvec); @@ -962,115 +1172,7 @@ static inline void note_zone_scanning_priority(struct zone *zone, int priority) static inline int zone_is_near_oom(struct zone *zone) { - return zone->pages_scanned >= (zone_page_state(zone, NR_ACTIVE) - + zone_page_state(zone, NR_INACTIVE))*3; -} - -/* - * Determine we should try to reclaim mapped pages. - * This is called only when sc->mem_cgroup is NULL. - */ -static int calc_reclaim_mapped(struct scan_control *sc, struct zone *zone, - int priority) -{ - long mapped_ratio; - long distress; - long swap_tendency; - long imbalance; - int reclaim_mapped = 0; - int prev_priority; - - if (scan_global_lru(sc) && zone_is_near_oom(zone)) - return 1; - /* - * `distress' is a measure of how much trouble we're having - * reclaiming pages. 0 -> no problems. 100 -> great trouble. - */ - if (scan_global_lru(sc)) - prev_priority = zone->prev_priority; - else - prev_priority = mem_cgroup_get_reclaim_priority(sc->mem_cgroup); - - distress = 100 >> min(prev_priority, priority); - - /* - * The point of this algorithm is to decide when to start - * reclaiming mapped memory instead of just pagecache. Work out - * how much memory - * is mapped. - */ - if (scan_global_lru(sc)) - mapped_ratio = ((global_page_state(NR_FILE_MAPPED) + - global_page_state(NR_ANON_PAGES)) * 100) / - vm_total_pages; - else - mapped_ratio = mem_cgroup_calc_mapped_ratio(sc->mem_cgroup); - - /* - * Now decide how much we really want to unmap some pages. The - * mapped ratio is downgraded - just because there's a lot of - * mapped memory doesn't necessarily mean that page reclaim - * isn't succeeding. - * - * The distress ratio is important - we don't want to start - * going oom. - * - * A 100% value of vm_swappiness overrides this algorithm - * altogether. - */ - swap_tendency = mapped_ratio / 2 + distress + sc->swappiness; - - /* - * If there's huge imbalance between active and inactive - * (think active 100 times larger than inactive) we should - * become more permissive, or the system will take too much - * cpu before it start swapping during memory pressure. - * Distress is about avoiding early-oom, this is about - * making swappiness graceful despite setting it to low - * values. - * - * Avoid div by zero with nr_inactive+1, and max resulting - * value is vm_total_pages. - */ - if (scan_global_lru(sc)) { - imbalance = zone_page_state(zone, NR_ACTIVE); - imbalance /= zone_page_state(zone, NR_INACTIVE) + 1; - } else - imbalance = mem_cgroup_reclaim_imbalance(sc->mem_cgroup); - - /* - * Reduce the effect of imbalance if swappiness is low, - * this means for a swappiness very low, the imbalance - * must be much higher than 100 for this logic to make - * the difference. - * - * Max temporary value is vm_total_pages*100. - */ - imbalance *= (vm_swappiness + 1); - imbalance /= 100; - - /* - * If not much of the ram is mapped, makes the imbalance - * less relevant, it's high priority we refill the inactive - * list with mapped pages only in presence of high ratio of - * mapped pages. - * - * Max temporary value is vm_total_pages*100. - */ - imbalance *= mapped_ratio; - imbalance /= 100; - - /* apply imbalance feedback to swap_tendency */ - swap_tendency += imbalance; - - /* - * Now use this metric to decide whether to start moving mapped - * memory onto the inactive list. - */ - if (swap_tendency >= 100) - reclaim_mapped = 1; - - return reclaim_mapped; + return zone->pages_scanned >= (zone_lru_pages(zone) * 3); } /* @@ -1093,53 +1195,71 @@ static int calc_reclaim_mapped(struct scan_control *sc, struct zone *zone, static void shrink_active_list(unsigned long nr_pages, struct zone *zone, - struct scan_control *sc, int priority) + struct scan_control *sc, int priority, int file) { unsigned long pgmoved; int pgdeactivate = 0; unsigned long pgscanned; LIST_HEAD(l_hold); /* The pages which were snipped off */ - LIST_HEAD(l_inactive); /* Pages to go onto the inactive_list */ - LIST_HEAD(l_active); /* Pages to go onto the active_list */ + LIST_HEAD(l_inactive); struct page *page; struct pagevec pvec; - int reclaim_mapped = 0; - - if (sc->may_swap) - reclaim_mapped = calc_reclaim_mapped(sc, zone, priority); + enum lru_list lru; lru_add_drain(); spin_lock_irq(&zone->lru_lock); pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order, ISOLATE_ACTIVE, zone, - sc->mem_cgroup, 1); + sc->mem_cgroup, 1, file); /* * zone->pages_scanned is used for detect zone's oom * mem_cgroup remembers nr_scan by itself. */ - if (scan_global_lru(sc)) + if (scan_global_lru(sc)) { zone->pages_scanned += pgscanned; + zone->recent_scanned[!!file] += pgmoved; + } - __mod_zone_page_state(zone, NR_ACTIVE, -pgmoved); + if (file) + __mod_zone_page_state(zone, NR_ACTIVE_FILE, -pgmoved); + else + __mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved); spin_unlock_irq(&zone->lru_lock); + pgmoved = 0; while (!list_empty(&l_hold)) { cond_resched(); page = lru_to_page(&l_hold); list_del(&page->lru); - if (page_mapped(page)) { - if (!reclaim_mapped || - (total_swap_pages == 0 && PageAnon(page)) || - page_referenced(page, 0, sc->mem_cgroup)) { - list_add(&page->lru, &l_active); - continue; - } + + if (unlikely(!page_evictable(page, NULL))) { + putback_lru_page(page); + continue; } + + /* page_referenced clears PageReferenced */ + if (page_mapping_inuse(page) && + page_referenced(page, 0, sc->mem_cgroup)) + pgmoved++; + list_add(&page->lru, &l_inactive); } + /* + * Count referenced pages from currently used mappings as + * rotated, even though they are moved to the inactive list. + * This helps balance scan pressure between file and anonymous + * pages in get_scan_ratio. + */ + zone->recent_rotated[!!file] += pgmoved; + + /* + * Move the pages to the [file or anon] inactive list. + */ pagevec_init(&pvec, 1); + pgmoved = 0; + lru = LRU_BASE + file * LRU_FILE; spin_lock_irq(&zone->lru_lock); while (!list_empty(&l_inactive)) { page = lru_to_page(&l_inactive); @@ -1149,11 +1269,11 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone, VM_BUG_ON(!PageActive(page)); ClearPageActive(page); - list_move(&page->lru, &zone->inactive_list); - mem_cgroup_move_lists(page, false); + list_move(&page->lru, &zone->lru[lru].list); + mem_cgroup_move_lists(page, lru); pgmoved++; if (!pagevec_add(&pvec, page)) { - __mod_zone_page_state(zone, NR_INACTIVE, pgmoved); + __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); spin_unlock_irq(&zone->lru_lock); pgdeactivate += pgmoved; pgmoved = 0; @@ -1163,104 +1283,189 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone, spin_lock_irq(&zone->lru_lock); } } - __mod_zone_page_state(zone, NR_INACTIVE, pgmoved); + __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); pgdeactivate += pgmoved; if (buffer_heads_over_limit) { spin_unlock_irq(&zone->lru_lock); pagevec_strip(&pvec); spin_lock_irq(&zone->lru_lock); } - - pgmoved = 0; - while (!list_empty(&l_active)) { - page = lru_to_page(&l_active); - prefetchw_prev_lru_page(page, &l_active, flags); - VM_BUG_ON(PageLRU(page)); - SetPageLRU(page); - VM_BUG_ON(!PageActive(page)); - - list_move(&page->lru, &zone->active_list); - mem_cgroup_move_lists(page, true); - pgmoved++; - if (!pagevec_add(&pvec, page)) { - __mod_zone_page_state(zone, NR_ACTIVE, pgmoved); - pgmoved = 0; - spin_unlock_irq(&zone->lru_lock); - __pagevec_release(&pvec); - spin_lock_irq(&zone->lru_lock); - } - } - __mod_zone_page_state(zone, NR_ACTIVE, pgmoved); - __count_zone_vm_events(PGREFILL, zone, pgscanned); __count_vm_events(PGDEACTIVATE, pgdeactivate); spin_unlock_irq(&zone->lru_lock); + if (vm_swap_full()) + pagevec_swap_free(&pvec); pagevec_release(&pvec); } +static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, + struct zone *zone, struct scan_control *sc, int priority) +{ + int file = is_file_lru(lru); + + if (lru == LRU_ACTIVE_FILE) { + shrink_active_list(nr_to_scan, zone, sc, priority, file); + return 0; + } + + if (lru == LRU_ACTIVE_ANON && + (!scan_global_lru(sc) || inactive_anon_is_low(zone))) { + shrink_active_list(nr_to_scan, zone, sc, priority, file); + return 0; + } + return shrink_inactive_list(nr_to_scan, zone, sc, priority, file); +} + +/* + * Determine how aggressively the anon and file LRU lists should be + * scanned. The relative value of each set of LRU lists is determined + * by looking at the fraction of the pages scanned we did rotate back + * onto the active list instead of evict. + * + * percent[0] specifies how much pressure to put on ram/swap backed + * memory, while percent[1] determines pressure on the file LRUs. + */ +static void get_scan_ratio(struct zone *zone, struct scan_control *sc, + unsigned long *percent) +{ + unsigned long anon, file, free; + unsigned long anon_prio, file_prio; + unsigned long ap, fp; + + anon = zone_page_state(zone, NR_ACTIVE_ANON) + + zone_page_state(zone, NR_INACTIVE_ANON); + file = zone_page_state(zone, NR_ACTIVE_FILE) + + zone_page_state(zone, NR_INACTIVE_FILE); + free = zone_page_state(zone, NR_FREE_PAGES); + + /* If we have no swap space, do not bother scanning anon pages. */ + if (nr_swap_pages <= 0) { + percent[0] = 0; + percent[1] = 100; + return; + } + + /* If we have very few page cache pages, force-scan anon pages. */ + if (unlikely(file + free <= zone->pages_high)) { + percent[0] = 100; + percent[1] = 0; + return; + } + + /* + * OK, so we have swap space and a fair amount of page cache + * pages. We use the recently rotated / recently scanned + * ratios to determine how valuable each cache is. + * + * Because workloads change over time (and to avoid overflow) + * we keep these statistics as a floating average, which ends + * up weighing recent references more than old ones. + * + * anon in [0], file in [1] + */ + if (unlikely(zone->recent_scanned[0] > anon / 4)) { + spin_lock_irq(&zone->lru_lock); + zone->recent_scanned[0] /= 2; + zone->recent_rotated[0] /= 2; + spin_unlock_irq(&zone->lru_lock); + } + + if (unlikely(zone->recent_scanned[1] > file / 4)) { + spin_lock_irq(&zone->lru_lock); + zone->recent_scanned[1] /= 2; + zone->recent_rotated[1] /= 2; + spin_unlock_irq(&zone->lru_lock); + } + + /* + * With swappiness at 100, anonymous and file have the same priority. + * This scanning priority is essentially the inverse of IO cost. + */ + anon_prio = sc->swappiness; + file_prio = 200 - sc->swappiness; + + /* + * anon recent_rotated[0] + * %anon = 100 * ----------- / ----------------- * IO cost + * anon + file rotate_sum + */ + ap = (anon_prio + 1) * (zone->recent_scanned[0] + 1); + ap /= zone->recent_rotated[0] + 1; + + fp = (file_prio + 1) * (zone->recent_scanned[1] + 1); + fp /= zone->recent_rotated[1] + 1; + + /* Normalize to percentages */ + percent[0] = 100 * ap / (ap + fp + 1); + percent[1] = 100 - percent[0]; +} + + /* * This is a basic per-zone page freer. Used by both kswapd and direct reclaim. */ static unsigned long shrink_zone(int priority, struct zone *zone, struct scan_control *sc) { - unsigned long nr_active; - unsigned long nr_inactive; + unsigned long nr[NR_LRU_LISTS]; unsigned long nr_to_scan; unsigned long nr_reclaimed = 0; + unsigned long percent[2]; /* anon @ 0; file @ 1 */ + enum lru_list l; - if (scan_global_lru(sc)) { - /* - * Add one to nr_to_scan just to make sure that the kernel - * will slowly sift through the active list. - */ - zone->nr_scan_active += - (zone_page_state(zone, NR_ACTIVE) >> priority) + 1; - nr_active = zone->nr_scan_active; - zone->nr_scan_inactive += - (zone_page_state(zone, NR_INACTIVE) >> priority) + 1; - nr_inactive = zone->nr_scan_inactive; - if (nr_inactive >= sc->swap_cluster_max) - zone->nr_scan_inactive = 0; - else - nr_inactive = 0; - - if (nr_active >= sc->swap_cluster_max) - zone->nr_scan_active = 0; - else - nr_active = 0; - } else { - /* - * This reclaim occurs not because zone memory shortage but - * because memory controller hits its limit. - * Then, don't modify zone reclaim related data. - */ - nr_active = mem_cgroup_calc_reclaim_active(sc->mem_cgroup, - zone, priority); - - nr_inactive = mem_cgroup_calc_reclaim_inactive(sc->mem_cgroup, - zone, priority); - } + get_scan_ratio(zone, sc, percent); + for_each_evictable_lru(l) { + if (scan_global_lru(sc)) { + int file = is_file_lru(l); + int scan; - while (nr_active || nr_inactive) { - if (nr_active) { - nr_to_scan = min(nr_active, - (unsigned long)sc->swap_cluster_max); - nr_active -= nr_to_scan; - shrink_active_list(nr_to_scan, zone, sc, priority); + scan = zone_page_state(zone, NR_LRU_BASE + l); + if (priority) { + scan >>= priority; + scan = (scan * percent[file]) / 100; + } + zone->lru[l].nr_scan += scan; + nr[l] = zone->lru[l].nr_scan; + if (nr[l] >= sc->swap_cluster_max) + zone->lru[l].nr_scan = 0; + else + nr[l] = 0; + } else { + /* + * This reclaim occurs not because zone memory shortage + * but because memory controller hits its limit. + * Don't modify zone reclaim related data. + */ + nr[l] = mem_cgroup_calc_reclaim(sc->mem_cgroup, zone, + priority, l); } + } - if (nr_inactive) { - nr_to_scan = min(nr_inactive, + while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] || + nr[LRU_INACTIVE_FILE]) { + for_each_evictable_lru(l) { + if (nr[l]) { + nr_to_scan = min(nr[l], (unsigned long)sc->swap_cluster_max); - nr_inactive -= nr_to_scan; - nr_reclaimed += shrink_inactive_list(nr_to_scan, zone, - sc); + nr[l] -= nr_to_scan; + + nr_reclaimed += shrink_list(l, nr_to_scan, + zone, sc, priority); + } } } + /* + * Even if we did not try to evict anon pages at all, we want to + * rebalance the anon lru active/inactive ratio. + */ + if (!scan_global_lru(sc) || inactive_anon_is_low(zone)) + shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); + else if (!scan_global_lru(sc)) + shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0); + throttle_vm_writeout(sc->gfp_mask); return nr_reclaimed; } @@ -1321,7 +1526,7 @@ static unsigned long shrink_zones(int priority, struct zonelist *zonelist, return nr_reclaimed; } - + /* * This is the main entry point to direct page reclaim. * @@ -1364,8 +1569,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) continue; - lru_pages += zone_page_state(zone, NR_ACTIVE) - + zone_page_state(zone, NR_INACTIVE); + lru_pages += zone_lru_pages(zone); } } @@ -1555,6 +1759,14 @@ loop_again: priority != DEF_PRIORITY) continue; + /* + * Do some background aging of the anon list, to give + * pages a chance to be referenced before reclaiming. + */ + if (inactive_anon_is_low(zone)) + shrink_active_list(SWAP_CLUSTER_MAX, zone, + &sc, priority, 0); + if (!zone_watermark_ok(zone, order, zone->pages_high, 0, 0)) { end_zone = i; @@ -1567,8 +1779,7 @@ loop_again: for (i = 0; i <= end_zone; i++) { struct zone *zone = pgdat->node_zones + i; - lru_pages += zone_page_state(zone, NR_ACTIVE) - + zone_page_state(zone, NR_INACTIVE); + lru_pages += zone_lru_pages(zone); } /* @@ -1612,8 +1823,7 @@ loop_again: if (zone_is_all_unreclaimable(zone)) continue; if (nr_slab == 0 && zone->pages_scanned >= - (zone_page_state(zone, NR_ACTIVE) - + zone_page_state(zone, NR_INACTIVE)) * 6) + (zone_lru_pages(zone) * 6)) zone_set_flag(zone, ZONE_ALL_UNRECLAIMABLE); /* @@ -1667,7 +1877,7 @@ out: /* * The background pageout daemon, started as a kernel thread - * from the init process. + * from the init process. * * This basically trickles out pages so that we have _some_ * free memory available even if there is no other activity @@ -1761,6 +1971,14 @@ void wakeup_kswapd(struct zone *zone, int order) wake_up_interruptible(&pgdat->kswapd_wait); } +unsigned long global_lru_pages(void) +{ + return global_page_state(NR_ACTIVE_ANON) + + global_page_state(NR_ACTIVE_FILE) + + global_page_state(NR_INACTIVE_ANON) + + global_page_state(NR_INACTIVE_FILE); +} + #ifdef CONFIG_PM /* * Helper function for shrink_all_memory(). Tries to reclaim 'nr_pages' pages @@ -1774,6 +1992,7 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio, { struct zone *zone; unsigned long nr_to_scan, ret = 0; + enum lru_list l; for_each_zone(zone) { @@ -1783,38 +2002,31 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio, if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY) continue; - /* For pass = 0 we don't shrink the active list */ - if (pass > 0) { - zone->nr_scan_active += - (zone_page_state(zone, NR_ACTIVE) >> prio) + 1; - if (zone->nr_scan_active >= nr_pages || pass > 3) { - zone->nr_scan_active = 0; + for_each_evictable_lru(l) { + /* For pass = 0, we don't shrink the active list */ + if (pass == 0 && + (l == LRU_ACTIVE || l == LRU_ACTIVE_FILE)) + continue; + + zone->lru[l].nr_scan += + (zone_page_state(zone, NR_LRU_BASE + l) + >> prio) + 1; + if (zone->lru[l].nr_scan >= nr_pages || pass > 3) { + zone->lru[l].nr_scan = 0; nr_to_scan = min(nr_pages, - zone_page_state(zone, NR_ACTIVE)); - shrink_active_list(nr_to_scan, zone, sc, prio); + zone_page_state(zone, + NR_LRU_BASE + l)); + ret += shrink_list(l, nr_to_scan, zone, + sc, prio); + if (ret >= nr_pages) + return ret; } } - - zone->nr_scan_inactive += - (zone_page_state(zone, NR_INACTIVE) >> prio) + 1; - if (zone->nr_scan_inactive >= nr_pages || pass > 3) { - zone->nr_scan_inactive = 0; - nr_to_scan = min(nr_pages, - zone_page_state(zone, NR_INACTIVE)); - ret += shrink_inactive_list(nr_to_scan, zone, sc); - if (ret >= nr_pages) - return ret; - } } return ret; } -static unsigned long count_lru_pages(void) -{ - return global_page_state(NR_ACTIVE) + global_page_state(NR_INACTIVE); -} - /* * Try to free `nr_pages' of memory, system-wide, and return the number of * freed pages. @@ -1840,7 +2052,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages) current->reclaim_state = &reclaim_state; - lru_pages = count_lru_pages(); + lru_pages = global_lru_pages(); nr_slab = global_page_state(NR_SLAB_RECLAIMABLE); /* If slab caches are huge, it's better to hit them first */ while (nr_slab >= lru_pages) { @@ -1883,7 +2095,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages) reclaim_state.reclaimed_slab = 0; shrink_slab(sc.nr_scanned, sc.gfp_mask, - count_lru_pages()); + global_lru_pages()); ret += reclaim_state.reclaimed_slab; if (ret >= nr_pages) goto out; @@ -1900,7 +2112,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages) if (!ret) { do { reclaim_state.reclaimed_slab = 0; - shrink_slab(nr_pages, sc.gfp_mask, count_lru_pages()); + shrink_slab(nr_pages, sc.gfp_mask, global_lru_pages()); ret += reclaim_state.reclaimed_slab; } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0); } @@ -2128,3 +2340,285 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) return ret; } #endif + +#ifdef CONFIG_UNEVICTABLE_LRU +/* + * page_evictable - test whether a page is evictable + * @page: the page to test + * @vma: the VMA in which the page is or will be mapped, may be NULL + * + * Test whether page is evictable--i.e., should be placed on active/inactive + * lists vs unevictable list. The vma argument is !NULL when called from the + * fault path to determine how to instantate a new page. + * + * Reasons page might not be evictable: + * (1) page's mapping marked unevictable + * (2) page is part of an mlocked VMA + * + */ +int page_evictable(struct page *page, struct vm_area_struct *vma) +{ + + if (mapping_unevictable(page_mapping(page))) + return 0; + + if (PageMlocked(page) || (vma && is_mlocked_vma(vma, page))) + return 0; + + return 1; +} + +static void show_page_path(struct page *page) +{ + char buf[256]; + if (page_is_file_cache(page)) { + struct address_space *mapping = page->mapping; + struct dentry *dentry; + pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); + + spin_lock(&mapping->i_mmap_lock); + dentry = d_find_alias(mapping->host); + printk(KERN_INFO "rescued: %s %lu\n", + dentry_path(dentry, buf, 256), pgoff); + spin_unlock(&mapping->i_mmap_lock); + } else { +#if defined(CONFIG_MM_OWNER) && defined(CONFIG_MMU) + struct anon_vma *anon_vma; + struct vm_area_struct *vma; + + anon_vma = page_lock_anon_vma(page); + if (!anon_vma) + return; + + list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { + printk(KERN_INFO "rescued: anon %s\n", + vma->vm_mm->owner->comm); + break; + } + page_unlock_anon_vma(anon_vma); +#endif + } +} + + +/** + * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list + * @page: page to check evictability and move to appropriate lru list + * @zone: zone page is in + * + * Checks a page for evictability and moves the page to the appropriate + * zone lru list. + * + * Restrictions: zone->lru_lock must be held, page must be on LRU and must + * have PageUnevictable set. + */ +static void check_move_unevictable_page(struct page *page, struct zone *zone) +{ + VM_BUG_ON(PageActive(page)); + +retry: + ClearPageUnevictable(page); + if (page_evictable(page, NULL)) { + enum lru_list l = LRU_INACTIVE_ANON + page_is_file_cache(page); + + show_page_path(page); + + __dec_zone_state(zone, NR_UNEVICTABLE); + list_move(&page->lru, &zone->lru[l].list); + __inc_zone_state(zone, NR_INACTIVE_ANON + l); + __count_vm_event(UNEVICTABLE_PGRESCUED); + } else { + /* + * rotate unevictable list + */ + SetPageUnevictable(page); + list_move(&page->lru, &zone->lru[LRU_UNEVICTABLE].list); + if (page_evictable(page, NULL)) + goto retry; + } +} + +/** + * scan_mapping_unevictable_pages - scan an address space for evictable pages + * @mapping: struct address_space to scan for evictable pages + * + * Scan all pages in mapping. Check unevictable pages for + * evictability and move them to the appropriate zone lru list. + */ +void scan_mapping_unevictable_pages(struct address_space *mapping) +{ + pgoff_t next = 0; + pgoff_t end = (i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1) >> + PAGE_CACHE_SHIFT; + struct zone *zone; + struct pagevec pvec; + + if (mapping->nrpages == 0) + return; + + pagevec_init(&pvec, 0); + while (next < end && + pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { + int i; + int pg_scanned = 0; + + zone = NULL; + + for (i = 0; i < pagevec_count(&pvec); i++) { + struct page *page = pvec.pages[i]; + pgoff_t page_index = page->index; + struct zone *pagezone = page_zone(page); + + pg_scanned++; + if (page_index > next) + next = page_index; + next++; + + if (pagezone != zone) { + if (zone) + spin_unlock_irq(&zone->lru_lock); + zone = pagezone; + spin_lock_irq(&zone->lru_lock); + } + + if (PageLRU(page) && PageUnevictable(page)) + check_move_unevictable_page(page, zone); + } + if (zone) + spin_unlock_irq(&zone->lru_lock); + pagevec_release(&pvec); + + count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned); + } + +} + +/** + * scan_zone_unevictable_pages - check unevictable list for evictable pages + * @zone - zone of which to scan the unevictable list + * + * Scan @zone's unevictable LRU lists to check for pages that have become + * evictable. Move those that have to @zone's inactive list where they + * become candidates for reclaim, unless shrink_inactive_zone() decides + * to reactivate them. Pages that are still unevictable are rotated + * back onto @zone's unevictable list. + */ +#define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */ +void scan_zone_unevictable_pages(struct zone *zone) +{ + struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list; + unsigned long scan; + unsigned long nr_to_scan = zone_page_state(zone, NR_UNEVICTABLE); + + while (nr_to_scan > 0) { + unsigned long batch_size = min(nr_to_scan, + SCAN_UNEVICTABLE_BATCH_SIZE); + + spin_lock_irq(&zone->lru_lock); + for (scan = 0; scan < batch_size; scan++) { + struct page *page = lru_to_page(l_unevictable); + + if (!trylock_page(page)) + continue; + + prefetchw_prev_lru_page(page, l_unevictable, flags); + + if (likely(PageLRU(page) && PageUnevictable(page))) + check_move_unevictable_page(page, zone); + + unlock_page(page); + } + spin_unlock_irq(&zone->lru_lock); + + nr_to_scan -= batch_size; + } +} + + +/** + * scan_all_zones_unevictable_pages - scan all unevictable lists for evictable pages + * + * A really big hammer: scan all zones' unevictable LRU lists to check for + * pages that have become evictable. Move those back to the zones' + * inactive list where they become candidates for reclaim. + * This occurs when, e.g., we have unswappable pages on the unevictable lists, + * and we add swap to the system. As such, it runs in the context of a task + * that has possibly/probably made some previously unevictable pages + * evictable. + */ +void scan_all_zones_unevictable_pages(void) +{ + struct zone *zone; + + for_each_zone(zone) { + scan_zone_unevictable_pages(zone); + } +} + +/* + * scan_unevictable_pages [vm] sysctl handler. On demand re-scan of + * all nodes' unevictable lists for evictable pages + */ +unsigned long scan_unevictable_pages; + +int scan_unevictable_handler(struct ctl_table *table, int write, + struct file *file, void __user *buffer, + size_t *length, loff_t *ppos) +{ + proc_doulongvec_minmax(table, write, file, buffer, length, ppos); + + if (write && *(unsigned long *)table->data) + scan_all_zones_unevictable_pages(); + + scan_unevictable_pages = 0; + return 0; +} + +/* + * per node 'scan_unevictable_pages' attribute. On demand re-scan of + * a specified node's per zone unevictable lists for evictable pages. + */ + +static ssize_t read_scan_unevictable_node(struct sys_device *dev, + struct sysdev_attribute *attr, + char *buf) +{ + return sprintf(buf, "0\n"); /* always zero; should fit... */ +} + +static ssize_t write_scan_unevictable_node(struct sys_device *dev, + struct sysdev_attribute *attr, + const char *buf, size_t count) +{ + struct zone *node_zones = NODE_DATA(dev->id)->node_zones; + struct zone *zone; + unsigned long res; + unsigned long req = strict_strtoul(buf, 10, &res); + + if (!req) + return 1; /* zero is no-op */ + + for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) { + if (!populated_zone(zone)) + continue; + scan_zone_unevictable_pages(zone); + } + return 1; +} + + +static SYSDEV_ATTR(scan_unevictable_pages, S_IRUGO | S_IWUSR, + read_scan_unevictable_node, + write_scan_unevictable_node); + +int scan_unevictable_register_node(struct node *node) +{ + return sysdev_create_file(&node->sysdev, &attr_scan_unevictable_pages); +} + +void scan_unevictable_unregister_node(struct node *node) +{ + sysdev_remove_file(&node->sysdev, &attr_scan_unevictable_pages); +} + +#endif |