From 6213055f2c068b63078649457391ecea9b489ea3 Mon Sep 17 00:00:00 2001 From: zhong jiang Date: Fri, 7 Oct 2016 17:01:19 -0700 Subject: 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 Suggested-by: Hugh Dickins Acked-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/ksm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/ksm.c b/mm/ksm.c index 5048083..9ae6011 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -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) -- cgit v1.1