[PATCH 4.5 013/124] mm: fix invalid node in alloc_migrate_target()

From: Greg Kroah-Hartman
Date: Sun Apr 17 2016 - 23:43:24 EST

4.5-stable review patch. If anyone has any objections, please let me know.


From: Xishi Qiu <qiuxishi@xxxxxxxxxx>

commit 6f25a14a7053b69917e2ebea0d31dd444cd31fd5 upstream.

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

Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Signed-off-by: Xishi Qiu <qiuxishi@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Joonsoo Kim <js1304@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: "Laura Abbott" <lauraa@xxxxxxxxxxxxxx>
Cc: Hui Zhu <zhuhui@xxxxxxxxxx>
Cc: Wang Xiaoqiang <wangxq10@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

mm/page_isolation.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -289,11 +289,11 @@ struct page *alloc_migrate_target(struct
* 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))