linux-kernel - Re: Still OOM problems with 4.9er/4.10er kernels

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Message-ID: <20170316093931.GH30501@dhcp22.suse.cz>
Date:   Thu, 16 Mar 2017 10:39:31 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     lkml@...garu.com
Cc:     Gerhard Wiesinger <lists@...singer.com>,
        Minchan Kim <minchan@...nel.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: Still OOM problems with 4.9er/4.10er kernels

On Thu 16-03-17 02:23:18, lkml@...garu.com wrote:
> On Thu, Mar 16, 2017 at 10:08:44AM +0100, Michal Hocko wrote:
> > On Thu 16-03-17 01:47:33, lkml@...garu.com wrote:
> > [...]
> > > While on the topic of understanding allocation stalls, Philip Freeman recently
> > > mailed linux-kernel with a similar report, and in his case there are plenty of
> > > page cache pages.  It was also a GFP_HIGHUSER_MOVABLE 0-order allocation.
> > 
> > care to point me to the report?
> 
> http://lkml.iu.edu/hypermail/linux/kernel/1703.1/06360.html

Thanks. It is gone from my lkml mailbox. Could you CC me (and linux-mm) please?
 
> >  
> > > I'm no MM expert, but it appears a bit broken for such a low-order allocation
> > > to stall on the order of 10 seconds when there's plenty of reclaimable pages,
> > > in addition to mostly unused and abundant swap space on SSD.
> > 
> > yes this might indeed signal a problem.
> 
> Well maybe I missed something obvious that a better informed eye will catch.

Nothing really obvious. There is indeed a lot of anonymous memory to
swap out. Almost no pages on file LRU lists (active_file:759
inactive_file:749) but 158783 total pagecache pages so we have to have a
lot of pages in the swap cache. I would probably have to see more data
to make a full picture.

-- 
Michal Hocko
SUSE Labs