linux-kernel - [PATCH 3.19.y-ckt 18/56] mm: fix invalid node in alloc_migrate

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Message-Id: <1460494754-32183-19-git-send-email-kamal@canonical.com>
Date:	Tue, 12 Apr 2016 13:58:36 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Xishi Qiu <qiuxishi@...wei.com>, Joonsoo Kim <js1304@...il.com>,
	David Rientjes <rientjes@...gle.com>,
	"Laura Abbott" <lauraa@...eaurora.org>,
	Hui Zhu <zhuhui@...omi.com>,
	Wang Xiaoqiang <wangxq10@....edu.cn>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 18/56] mm: fix invalid node in alloc_migrate_target()

3.19.8-ckt19 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Xishi Qiu <qiuxishi@...wei.com>

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
allocation.

Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Signed-off-by: Xishi Qiu <qiuxishi@...wei.com>
Acked-by: Vlastimil Babka <vbabka@...e.cz>
Acked-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: Joonsoo Kim <js1304@...il.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: "Laura Abbott" <lauraa@...eaurora.org>
Cc: Hui Zhu <zhuhui@...omi.com>
Cc: Wang Xiaoqiang <wangxq10@....edu.cn>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 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 755a42c..ce5e8bb 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -299,11 +299,11 @@ 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))
-- 
2.7.4