linux-kernel - Re: [patch] mm, oom: prevent soft lockup on memcg oom for UP systems

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Message-Id: <20200312153238.c8d25ea6994b54a2c4d5ae1f@linux-foundation.org>
Date:   Thu, 12 Mar 2020 15:32:38 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     David Rientjes <rientjes@...gle.com>
Cc:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...nel.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [patch] mm, oom: prevent soft lockup on memcg oom for UP
 systems

On Thu, 12 Mar 2020 11:07:15 -0700 (PDT) David Rientjes <rientjes@...gle.com> wrote:

> On Thu, 12 Mar 2020, Tetsuo Handa wrote:
> 
> > > On Thu, 12 Mar 2020, Tetsuo Handa wrote:
> > > > > If you have an alternate patch to try, we can test it.  But since this 
> > > > > cond_resched() is needed anyway, I'm not sure it will change the result.
> > > > 
> > > > schedule_timeout_killable(1) is an alternate patch to try; I don't think
> > > > that this cond_resched() is needed anyway.
> > > > 
> > > 
> > > You are suggesting schedule_timeout_killable(1) in shrink_node_memcgs()?
> > > 
> > 
> > Andrew Morton also mentioned whether cond_resched() in shrink_node_memcgs()
> > is enough. But like you mentioned,
> > 
> 
> It passes our testing because this is where the allocator is looping while 
> the victim is trying to exit if only it could be scheduled.

What happens if the allocator has SCHED_FIFO?