On Fri 13-01-12 17:32:27, KAMEZAWA Hiroyuki wrote:
>
> From 788aebf15f3fa37940e0745cab72547e20683bf2 Mon Sep 17 00:00:00 2001
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> 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).
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> ---
> 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
>
>
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--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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