Commit 6213055f authored Oct 07, 2016 by zhong jiang Committed by Linus Torvalds Oct 07, 2016

mm,ksm: add __GFP_HIGH to the allocation in alloc_stable_node()

According to Hugh's suggestion, alloc_stable_node() with GFP_KERNEL can
in rare cases cause a hung task warning.

At present, if alloc_stable_node() allocation fails, two break_cows may
want to allocate a couple of pages, and the issue will come up when free
memory is under pressure.

We fix it by adding __GFP_HIGH to GFP, to grant access to memory
reserves, increasing the likelihood of allocation success.

[akpm@linux-foundation.org: tweak comment]
Link: http://lkml.kernel.org/r/1474354484-58233-1-git-send-email-zhongjiang@huawei.com


Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ac34dcd2

mm/ksm.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -299,7 +299,12 @@ static inline void free_rmap_item(struct rmap_item *rmap_item)

		static inline struct stable_node *alloc_stable_node(void)
		{
		return kmem_cache_alloc(stable_node_cache, GFP_KERNEL);
		/*
		* The allocation can take too long with GFP_KERNEL when memory is under
		* pressure, which may lead to hung task warnings. Adding __GFP_HIGH
		* grants access to memory reserves, helping to avoid this problem.
		*/
		return kmem_cache_alloc(stable_node_cache, GFP_KERNEL \| __GFP_HIGH);
		}

		static inline void free_stable_node(struct stable_node *stable_node)