linux-kernel - Re: [PATCH mmotm] vmscan: handle may_swap more strictly (Re: [PATCH mmotm] vmscan: fix may

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Date:	Tue, 9 Jun 2009 16:28:13 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Cc:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>
Subject: Re: [PATCH mmotm] vmscan: handle may_swap more strictly (Re: [PATCH
 mmotm] vmscan: fix may_swap handling for memcg)

On Tue, 9 Jun 2009 16:13:30 +0900
Daisuke Nishimura <nishimura@....nes.nec.co.jp> wrote:

> > > and, too many recliaming pages is not only memcg issue. I don't think this
> > > patch provide generic solution.
> > > 
> > Ah, you're right. It's not only memcg issue.
> > 
> How about this one ?
> 
> ===
> From: Daisuke Nishimura <nishimura@....nes.nec.co.jp>
> 
> Commit 2e2e425989080cc534fc0fca154cae515f971cf5 ("vmscan,memcg: reintroduce
> sc->may_swap) add may_swap flag and handle it at get_scan_ratio().
> 
> But the result of get_scan_ratio() is ignored when priority == 0,
> so anon lru is scanned even if may_swap == 0 or nr_swap_pages == 0.
> IMHO, this is not an expected behavior.
> 
> As for memcg especially, because of this behavior many and many pages are
> swapped-out just in vain when oom is invoked by mem+swap limit.
> 
> This patch is for handling may_swap flag more strictly.
> 
> Signed-off-by: Daisuke Nishimura <nishimura@....nes.nec.co.jp>

Thanks,
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

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