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authorzhong jiang <zhongjiang@huawei.com>2016-10-07 17:01:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-07 18:46:29 -0700
commit6213055f2c068b63078649457391ecea9b489ea3 (patch)
treebb0c8260b211a968de71a05190155fe76da8c3bf /mm/ksm.c
parentac34dcd263a3afe9a2e4d58a2d93bb66d700ac7c (diff)
downloadlinux-6213055f2c068b63078649457391ecea9b489ea3.tar.bz2
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>
Diffstat (limited to 'mm/ksm.c')
-rw-r--r--mm/ksm.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index 5048083b60f2..9ae6011a41f8 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)