From 2bcf887963812c075f80a14e1fad8ec7e1c67acf Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Thu, 12 Jan 2012 17:19:56 -0800 Subject: [PATCH] mm: take pagevecs off reclaim stack Replace pagevecs in putback_lru_pages() and move_active_pages_to_lru() by lists of pages_to_free: then apply Konstantin Khlebnikov's free_hot_cold_page_list() to them instead of pagevec_release(). Which simplifies the flow (no need to drop and retake lock whenever pagevec fills up) and reduces stale addresses in stack backtraces (which often showed through the pagevecs); but more importantly, removes another 120 bytes from the deepest stacks in page reclaim. Although I've not recently seen an actual stack overflow here with a vanilla kernel, move_active_pages_to_lru() has often featured in deep backtraces. However, free_hot_cold_page_list() does not handle compound pages (nor need it: a Transparent HugePage would have been split by the time it reaches the call in shrink_page_list()), but it is possible for putback_lru_pages() or move_active_pages_to_lru() to be left holding the last reference on a THP, so must exclude the unlikely compound case before putting on pages_to_free. Remove pagevec_strip(), its work now done in move_active_pages_to_lru(). The pagevec in scan_mapping_unevictable_pages() remains in mm/vmscan.c, but that is never on the reclaim path, and cannot be replaced by a list. Signed-off-by: Hugh Dickins Reviewed-by: KOSAKI Motohiro Reviewed-by: Konstantin Khlebnikov Cc: KAMEZAWA Hiroyuki Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pagevec.h | 2 -- mm/swap.c | 19 -------------- mm/vmscan.c | 58 ++++++++++++++++++++++++++++------------- 3 files changed, 40 insertions(+), 39 deletions(-) diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h index ed17024d2ebe..9def9121f8a2 100644 --- a/include/linux/pagevec.h +++ b/include/linux/pagevec.h @@ -22,7 +22,6 @@ struct pagevec { void __pagevec_release(struct pagevec *pvec); void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru); -void pagevec_strip(struct pagevec *pvec); unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, pgoff_t start, unsigned nr_pages); unsigned pagevec_lookup_tag(struct pagevec *pvec, @@ -59,7 +58,6 @@ static inline unsigned pagevec_add(struct pagevec *pvec, struct page *page) return pagevec_space(pvec); } - static inline void pagevec_release(struct pagevec *pvec) { if (pagevec_count(pvec)) diff --git a/mm/swap.c b/mm/swap.c index db6defaf2e55..79c22a649a3e 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -23,7 +23,6 @@ #include #include #include -#include /* for try_to_release_page() */ #include #include #include @@ -730,24 +729,6 @@ void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list 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 diff --git a/mm/vmscan.c b/mm/vmscan.c index 25f90383b391..7724fb8e7498 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1398,12 +1398,10 @@ putback_lru_pages(struct mem_cgroup_zone *mz, struct scan_control *sc, struct list_head *page_list) { struct page *page; - struct pagevec pvec; + LIST_HEAD(pages_to_free); struct zone *zone = mz->zone; struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz); - pagevec_init(&pvec, 1); - /* * Put back any unfreeable pages. */ @@ -1427,17 +1425,24 @@ putback_lru_pages(struct mem_cgroup_zone *mz, struct scan_control *sc, int numpages = hpage_nr_pages(page); reclaim_stat->recent_rotated[file] += numpages; } - if (!pagevec_add(&pvec, page)) { - spin_unlock_irq(&zone->lru_lock); - __pagevec_release(&pvec); - spin_lock_irq(&zone->lru_lock); + if (put_page_testzero(page)) { + __ClearPageLRU(page); + __ClearPageActive(page); + del_page_from_lru_list(zone, page, lru); + + if (unlikely(PageCompound(page))) { + spin_unlock_irq(&zone->lru_lock); + (*get_compound_page_dtor(page))(page); + spin_lock_irq(&zone->lru_lock); + } else + list_add(&page->lru, &pages_to_free); } } __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon); __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file); spin_unlock_irq(&zone->lru_lock); - pagevec_release(&pvec); + free_hot_cold_page_list(&pages_to_free, 1); } static noinline_for_stack void @@ -1647,13 +1652,23 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz, static void move_active_pages_to_lru(struct zone *zone, struct list_head *list, + struct list_head *pages_to_free, enum lru_list lru) { unsigned long pgmoved = 0; - struct pagevec pvec; struct page *page; - pagevec_init(&pvec, 1); + if (buffer_heads_over_limit) { + spin_unlock_irq(&zone->lru_lock); + list_for_each_entry(page, list, lru) { + if (page_has_private(page) && trylock_page(page)) { + if (page_has_private(page)) + try_to_release_page(page, 0); + unlock_page(page); + } + } + spin_lock_irq(&zone->lru_lock); + } while (!list_empty(list)) { struct lruvec *lruvec; @@ -1667,12 +1682,17 @@ static void move_active_pages_to_lru(struct zone *zone, list_move(&page->lru, &lruvec->lists[lru]); pgmoved += hpage_nr_pages(page); - if (!pagevec_add(&pvec, page) || list_empty(list)) { - spin_unlock_irq(&zone->lru_lock); - if (buffer_heads_over_limit) - pagevec_strip(&pvec); - __pagevec_release(&pvec); - spin_lock_irq(&zone->lru_lock); + if (put_page_testzero(page)) { + __ClearPageLRU(page); + __ClearPageActive(page); + del_page_from_lru_list(zone, page, lru); + + if (unlikely(PageCompound(page))) { + spin_unlock_irq(&zone->lru_lock); + (*get_compound_page_dtor(page))(page); + spin_lock_irq(&zone->lru_lock); + } else + list_add(&page->lru, pages_to_free); } } __mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved); @@ -1766,12 +1786,14 @@ static void shrink_active_list(unsigned long nr_pages, */ reclaim_stat->recent_rotated[file] += nr_rotated; - move_active_pages_to_lru(zone, &l_active, + move_active_pages_to_lru(zone, &l_active, &l_hold, LRU_ACTIVE + file * LRU_FILE); - move_active_pages_to_lru(zone, &l_inactive, + move_active_pages_to_lru(zone, &l_inactive, &l_hold, LRU_BASE + file * LRU_FILE); __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken); spin_unlock_irq(&zone->lru_lock); + + free_hot_cold_page_list(&l_hold, 1); } #ifdef CONFIG_SWAP -- 2.30.2