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>
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 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)