From: Miaohe Lin linmiaohe@huawei.com Subject: 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 ---

mm/page_alloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/page_alloc.c~mm-page_allocc-avoid-accessing-uninitialized-pcp-page-migratetype +++ a/mm/page_alloc.c @@ -3428,8 +3428,10 @@ void free_unref_page_list(struct list_he /* 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 _