From: zhong jiang <zhongjiang@xxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxx: tweak comment] Link: http://lkml.kernel.org/r/1474354484-58233-1-git-send-email-zhongjiang@xxxxxxxxxx Signed-off-by: zhong jiang <zhongjiang@xxxxxxxxxx> Suggested-by: Hugh Dickins <hughd@xxxxxxxxxx> Acked-by: Hugh Dickins <hughd@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/ksm.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff -puN mm/ksm.c~mmksm-add-__gfp_high-to-the-allocation-in-alloc_stable_node mm/ksm.c --- a/mm/ksm.c~mmksm-add-__gfp_high-to-the-allocation-in-alloc_stable_node +++ a/mm/ksm.c @@ -299,7 +299,12 @@ static inline void free_rmap_item(struct 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) _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
