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

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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>
This commit is contained in:
zhong jiang 2016-10-07 17:01:19 -07:00 committed by Linus Torvalds
parent ac34dcd263
commit 6213055f2c
1 changed files with 6 additions and 1 deletions
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7
mm/ksm.c
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@ -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)