linux-kernel - Re: [RFC PATCH 1/2] mm, vmscan: account the number of isolated pages per zone

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Message-ID: <20170125095337.GF32377@dhcp22.suse.cz>
Date:   Wed, 25 Jan 2017 10:53:38 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:     mgorman@...e.de, linux-mm@...ck.org, hannes@...xchg.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 1/2] mm, vmscan: account the number of isolated pages
 per zone

On Fri 20-01-17 22:27:27, Tetsuo Handa wrote:
> Mel Gorman wrote:
> > On Thu, Jan 19, 2017 at 12:23:36PM +0100, Michal Hocko wrote:
> > > So what do you think about the following? Tetsuo, would you be willing
> > > to run this patch through your torture testing please?
> > 
> > I'm fine with treating this as a starting point.
> 
> OK. So I tried to test this patch but I failed at preparation step.
> There are too many pending mm patches and I'm not sure which patch on
> which linux-next snapshot I should try.

The current linux-next should be good to test. It contains all patches
sitting in the mmotm tree. If you want a more stable base then you can
use mmotm git tree
(git://git.kernel.org/pub/scm/linux/kernel/git/mhocko/mm.git #since-4.9
or its #auto-latest alias)

> Also as another question,
> too_many_isolated() loop exists in both mm/vmscan.c and mm/compaction.c
> but why this patch does not touch the loop in mm/compaction.c part?

I am not yet convinced the compaction suffers from the same problem.
Compaction backs off much sooner so that path shouldn't get into
pathological situation AFAICS. I might be wrong here but I think we
should start with the reclaim path first.
-- 
Michal Hocko
SUSE Labs