linux-kernel - Re: [PATCH] memcg: oom: ignore oom warnings from memory.max

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Message-ID: <20200430202319.GF339283@carbon.dhcp.thefacebook.com>
Date:   Thu, 30 Apr 2020 13:23:19 -0700
From:   Roman Gushchin <guro@...com>
To:     Johannes Weiner <hannes@...xchg.org>
CC:     Shakeel Butt <shakeelb@...gle.com>,
        Michal Hocko <mhocko@...nel.org>,
        Greg Thelen <gthelen@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        <linux-mm@...ck.org>, <cgroups@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] memcg: oom: ignore oom warnings from memory.max

On Thu, Apr 30, 2020 at 03:30:49PM -0400, Johannes Weiner wrote:
> On Thu, Apr 30, 2020 at 12:06:10PM -0700, Roman Gushchin wrote:
> > On Thu, Apr 30, 2020 at 11:27:12AM -0700, Shakeel Butt wrote:
> > > @@ -6106,7 +6107,7 @@ static ssize_t memory_max_write(struct kernfs_open_file *of,
> > >  		}
> > >  
> > >  		memcg_memory_event(memcg, MEMCG_OOM);
> > > -		if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0))
> > > +		if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0, true))
> > 
> > I wonder if we can handle it automatically from the oom_killer side?
> > We can suppress warnings if oc->memcg is set and the cgroup scanning
> > showed that there are no belonging processes?
> 
> Note that we do remote charging for certain consumers, where memory
> gets charged from the outside of the cgroup.
> 
> We would want to know if these cause OOMs on an empty cgroup, rather
> than force-charge the allocations quietly.
> 

Yeah, good point.