From 0030f535a5cf9b1841d2088c10a0b2f8f2987460 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Tue, 31 Jul 2012 16:45:25 -0700 Subject: mm: memcg: fix compaction/migration failing due to memcg limits Compaction (and page migration in general) can currently be hindered through pages being owned by memory cgroups that are at their limits and unreclaimable. The reason is that the replacement page is being charged against the limit while the page being replaced is also still charged. But this seems unnecessary, given that only one of the two pages will still be in use after migration finishes. This patch changes the memcg migration sequence so that the replacement page is not charged. Whatever page is still in use after successful or failed migration gets to keep the charge of the page that was going to be replaced. The replacement page will still show up temporarily in the rss/cache statistics, this can be fixed in a later patch as it's less urgent. Reported-by: David Rientjes Signed-off-by: Johannes Weiner Acked-by: KAMEZAWA Hiroyuki Acked-by: Michal Hocko Cc: Hugh Dickins Cc: David Rientjes Cc: Wanpeng Li Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/memcontrol.h | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'include') diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 5a3ee6423634..8d9489fdab2e 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -98,9 +98,9 @@ int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *cgroup) extern struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg); -extern int -mem_cgroup_prepare_migration(struct page *page, - struct page *newpage, struct mem_cgroup **memcgp, gfp_t gfp_mask); +extern void +mem_cgroup_prepare_migration(struct page *page, struct page *newpage, + struct mem_cgroup **memcgp); extern void mem_cgroup_end_migration(struct mem_cgroup *memcg, struct page *oldpage, struct page *newpage, bool migration_ok); @@ -276,11 +276,10 @@ static inline struct cgroup_subsys_state return NULL; } -static inline int +static inline void mem_cgroup_prepare_migration(struct page *page, struct page *newpage, - struct mem_cgroup **memcgp, gfp_t gfp_mask) + struct mem_cgroup **memcgp) { - return 0; } static inline void mem_cgroup_end_migration(struct mem_cgroup *memcg, -- cgit v1.2.3