From: Miaohe Lin <linmiaohe@huawei.com>
Date: Thu, 9 Sep 2021 01:10:11 +0000 (-0700)
Subject: mm/page_alloc.c: avoid accessing uninitialized pcp page migratetype
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=053cfda102306a3394012f9fe2594811c34925e4;p=linux.git

mm/page_alloc.c: avoid accessing uninitialized pcp page migratetype

If it's not prepared to free unref page, the pcp page migratetype is
unset.  Thus we will get rubbish from get_pcppage_migratetype() and
might list_del(&page->lru) again after it's already deleted from the list
leading to grumble about data corruption.

Link: https://lkml.kernel.org/r/20210902115447.57050-1-linmiaohe@huawei.com
Fixes: df1acc856923 ("mm/page_alloc: avoid conflating IRQs disabled with zone->lock")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index de309a1dfe652..b37435c274cf1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3428,8 +3428,10 @@ void free_unref_page_list(struct list_head *list)
 	/* Prepare pages for freeing */
 	list_for_each_entry_safe(page, next, list, lru) {
 		pfn = page_to_pfn(page);
-		if (!free_unref_page_prepare(page, pfn, 0))
+		if (!free_unref_page_prepare(page, pfn, 0)) {
 			list_del(&page->lru);
+			continue;
+		}
 
 		/*
 		 * Free isolated pages directly to the allocator, see