Re: [RFC] [PATCH 1/7 v2] memcg: remove unnecessary check in mem_cgroup_update_page_stat()
From: Michal Hocko <hidden>
Date: 2012-01-17 15:16:23
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On Fri 13-01-12 17:32:27, KAMEZAWA Hiroyuki wrote:
From 788aebf15f3fa37940e0745cab72547e20683bf2 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki <redacted> Date: Thu, 12 Jan 2012 16:08:33 +0900 Subject: [PATCH 1/7] memcg: remove unnecessary check in mem_cgroup_update_page_stat() commit 10ea69f1182b removes move_lock_page_cgroup() in thp-split path. So, this PageTransHuge() check is unnecessary, too.
I do not see commit like that in the tree. I guess you meant memcg: make mem_cgroup_split_huge_fixup() more efficient which is not merged yet, right?
Note: - considering when mem_cgroup_update_page_stat() is called, there will be no race between split_huge_page() and update_page_stat(). All required locks are held in higher level.
We should never have THP page in this path in the first place. So why not changing this to VM_BUG_ON(PageTransHuge).
quoted hunk ↗ jump to hunk
Signed-off-by: KAMEZAWA Hiroyuki <redacted> --- mm/memcontrol.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 21ba356..08b988d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c@@ -1866,7 +1866,7 @@ void mem_cgroup_update_page_stat(struct page *page, if (unlikely(!memcg || !PageCgroupUsed(pc))) goto out; /* pc->mem_cgroup is unstable ? */ - if (unlikely(mem_cgroup_stealed(memcg)) || PageTransHuge(page)) { + if (unlikely(mem_cgroup_stealed(memcg))) { /* take a lock against to access pc->mem_cgroup */ move_lock_page_cgroup(pc, &flags); need_unlock = true;-- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
-- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>