Re: [PATCH] mm: fix invalid node in alloc_migrate_target()
From: Vlastimil Babka <hidden>
Date: 2016-03-29 12:25:10
Also in:
lkml
On 03/25/2016 07:56 AM, Xishi Qiu wrote:
It is incorrect to use next_node to find a target node, it will return MAX_NUMNODES or invalid node. This will lead to crash in buddy system allocation.
One possible place of crash is:
alloc_huge_page_node()
dequeue_huge_page_node()
[accesses h->hugepage_freelists[nid] with size MAX_NUMANODES]
Signed-off-by: Xishi Qiu <redacted>
Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to
handle hugepage")
Cc: stable
Acked-by: Vlastimil Babka <redacted>
quoted hunk ↗ jump to hunk
--- mm/page_isolation.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 92c4c36..31555b6 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c@@ -289,11 +289,11 @@ struct page *alloc_migrate_target(struct page *page, unsigned long private, * now as a simple work-around, we use the next node for destination. */ if (PageHuge(page)) { - nodemask_t src = nodemask_of_node(page_to_nid(page)); - nodemask_t dst; - nodes_complement(dst, src); + int node = next_online_node(page_to_nid(page)); + if (node == MAX_NUMNODES) + node = first_online_node; return alloc_huge_page_node(page_hstate(compound_head(page)), - next_node(page_to_nid(page), dst)); + node); } if (PageHighMem(page))
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