Re: [PATCH mmotm] vmscan: handle may_swap more strictly (Re: [PATCH mmotm] vmscan: fix may_swap handling for memcg)

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

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

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

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