From 77fe7f136a7312954b1b8b7eeb4bc91fc3c14a3f Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Tue, 22 Mar 2022 14:44:00 -0700 Subject: [PATCH] mm/page_alloc: check high-order pages for corruption during PCP operations Eric Dumazet pointed out that commit 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists") only checks the head page during PCP refill and allocation operations. This was an oversight and all pages should be checked. This will incur a small performance penalty but it's necessary for correctness. Link: https://lkml.kernel.org/r/20220310092456.GJ15701@techsingularity.net Fixes: 44042b449872 ("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists") Signed-off-by: Mel Gorman Reported-by: Eric Dumazet Acked-by: Eric Dumazet Reviewed-by: Shakeel Butt Acked-by: Vlastimil Babka Acked-by: David Rientjes Cc: Michal Hocko Cc: Wei Xu Cc: Greg Thelen Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 46 +++++++++++++++++++++++----------------------- 1 file changed, 23 insertions(+), 23 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 5d12685..e36d763 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2291,23 +2291,36 @@ static inline int check_new_page(struct page *page) return 1; } +static bool check_new_pages(struct page *page, unsigned int order) +{ + int i; + for (i = 0; i < (1 << order); i++) { + struct page *p = page + i; + + if (unlikely(check_new_page(p))) + return true; + } + + return false; +} + #ifdef CONFIG_DEBUG_VM /* * With DEBUG_VM enabled, order-0 pages are checked for expected state when * being allocated from pcp lists. With debug_pagealloc also enabled, they are * also checked when pcp lists are refilled from the free lists. */ -static inline bool check_pcp_refill(struct page *page) +static inline bool check_pcp_refill(struct page *page, unsigned int order) { if (debug_pagealloc_enabled_static()) - return check_new_page(page); + return check_new_pages(page, order); else return false; } -static inline bool check_new_pcp(struct page *page) +static inline bool check_new_pcp(struct page *page, unsigned int order) { - return check_new_page(page); + return check_new_pages(page, order); } #else /* @@ -2315,32 +2328,19 @@ static inline bool check_new_pcp(struct page *page) * when pcp lists are being refilled from the free lists. With debug_pagealloc * enabled, they are also checked when being allocated from the pcp lists. */ -static inline bool check_pcp_refill(struct page *page) +static inline bool check_pcp_refill(struct page *page, unsigned int order) { - return check_new_page(page); + return check_new_pages(page, order); } -static inline bool check_new_pcp(struct page *page) +static inline bool check_new_pcp(struct page *page, unsigned int order) { if (debug_pagealloc_enabled_static()) - return check_new_page(page); + return check_new_pages(page, order); else return false; } #endif /* CONFIG_DEBUG_VM */ -static bool check_new_pages(struct page *page, unsigned int order) -{ - int i; - for (i = 0; i < (1 << order); i++) { - struct page *p = page + i; - - if (unlikely(check_new_page(p))) - return true; - } - - return false; -} - inline void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags) { @@ -2982,7 +2982,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order, if (unlikely(page == NULL)) break; - if (unlikely(check_pcp_refill(page))) + if (unlikely(check_pcp_refill(page, order))) continue; /* @@ -3600,7 +3600,7 @@ struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order, page = list_first_entry(list, struct page, lru); list_del(&page->lru); pcp->count -= 1 << order; - } while (check_new_pcp(page)); + } while (check_new_pcp(page, order)); return page; } -- 2.7.4