From 787af64d05cd528aac9ad16752d11bb1c6061bb9 Mon Sep 17 00:00:00 2001
From: Zi Yan <ziy@nvidia.com>
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 <rostedt@goodmis.org>
Signed-off-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/page_alloc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index bdc8f60ae4622..6c6af86587757 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -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
--
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