linux-kernel - Re: [BUGFIX][PATCH 2/4] memcg: fix charge path for THP and allow early retirement

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Date:	Fri, 28 Jan 2011 14:37:28 +0900
From:	Daisuke Nishimura <nishimura@....nes.nec.co.jp>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"hannes@...xchg.org" <hannes@...xchg.org>,
	"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>,
	Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Subject: Re: [BUGFIX][PATCH 2/4] memcg: fix charge path for THP and allow
 early retirement

On Fri, 28 Jan 2011 12:26:08 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote:

> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> 
> When THP is used, Hugepage size charge can happen. It's not handled
> correctly in mem_cgroup_do_charge(). For example, THP can fallback
> to small page allocation when HUGEPAGE allocation seems difficult
> or busy, but memory cgroup doesn't understand it and continue to
> try HUGEPAGE charging. And the worst thing is memory cgroup
> believes 'memory reclaim succeeded' if limit - usage > PAGE_SIZE.
> 
> By this, khugepaged etc...can goes into inifinite reclaim loop
> if tasks in memcg are busy.
> 
> After this patch 
>  - Hugepage allocation will fail if 1st trial of page reclaim fails.
> 
> Changelog:
>  - make changes small. removed renaming codes.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

Acked-by: Daisuke Nishimura <nishimura@....nes.nec.co.jp>

Thanks,
Daisuke Nishimura.
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