From 787af64d05cd528aac9ad16752d11bb1c6061bb9 Mon Sep 17 00:00:00 2001 From: Zi Yan Date: Wed, 30 Mar 2022 15:45:43 -0700 Subject: [PATCH] mm: page_alloc: validate buddy before check its migratetype. Whenever a buddy page is found, page_is_buddy() should be called to check its validity. Add the missing check during pageblock merge check. Fixes: 1dd214b8f21c ("mm: page_alloc: avoid merging non-fallbackable pageblocks with others") Link: https://lore.kernel.org/all/20220330154208.71aca532@gandalf.local.home/ Reported-and-tested-by: Steven Rostedt Signed-off-by: Zi Yan Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index bdc8f60..6c6af86 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1108,6 +1108,9 @@ continue_merging: buddy_pfn = __find_buddy_pfn(pfn, order); buddy = page + (buddy_pfn - pfn); + + if (!page_is_buddy(page, buddy, order)) + goto done_merging; buddy_mt = get_pageblock_migratetype(buddy); if (migratetype != buddy_mt -- 2.7.4