Commit 787af64d authored by Zi Yan's avatar Zi Yan Committed by Linus Torvalds
Browse files

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: 1dd214b8 ("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: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarZi Yan <ziy@nvidia.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d5fd43ba

mm/page_alloc.c

+3 −0
Original line number Diff line number Diff line
@@ -1108,6 +1108,9 @@ static inline void __free_one_page(struct page *page, 


		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