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authorHugh Dickins <hughd@google.com>2022-10-22 10:51:06 +0300
committerAndrew Morton <akpm@linux-foundation.org>2022-10-28 23:37:22 +0300
commit5aae9265ee1a30cf716d6caf6b29fe99b9d55130 (patch)
treef3e214d827733b0995e8eada8d3d342fd1f4f7f2 /mm/page_alloc.c
parent8ebe0a5eaaeb099de03d09ad20f54ed962e2261e (diff)
downloadlinux-5aae9265ee1a30cf716d6caf6b29fe99b9d55130.tar.xz
mm: prep_compound_tail() clear page->private
Although page allocation always clears page->private in the first page or head page of an allocation, it has never made a point of clearing page->private in the tails (though 0 is often what is already there). But now commit 71e2d666ef85 ("mm/huge_memory: do not clobber swp_entry_t during THP split") issues a warning when page_tail->private is found to be non-0 (unless it's swapcache). Change that warning to dump page_tail (which also dumps head), instead of just the head: so far we have seen dead000000000122, dead000000000003, dead000000000001 or 0000000000000002 in the raw output for tail private. We could just delete the warning, but today's consensus appears to want page->private to be 0, unless there's a good reason for it to be set: so now clear it in prep_compound_tail() (more general than just for THP; but not for high order allocation, which makes no pass down the tails). Link: https://lkml.kernel.org/r/1c4233bb-4e4d-5969-fbd4-96604268a285@google.com Fixes: 71e2d666ef85 ("mm/huge_memory: do not clobber swp_entry_t during THP split") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b5a6c815ae28..218b28ee49ed 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -807,6 +807,7 @@ static void prep_compound_tail(struct page *head, int tail_idx)
p->mapping = TAIL_MAPPING;
set_compound_head(p, head);
+ set_page_private(p, 0);
}
void prep_compound_page(struct page *page, unsigned int order)