linux-kernel - Re: [PATCH memcg 0/1] false global OOM triggered by memcg-limited task

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Date:   Mon, 18 Oct 2021 18:51:24 +0200
From:   Michal Hocko <mhocko@...e.com>
To:     Shakeel Butt <shakeelb@...gle.com>
Cc:     Vasily Averin <vvs@...tuozzo.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Roman Gushchin <guro@...com>,
        Uladzislau Rezki <urezki@...il.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Cgroups <cgroups@...r.kernel.org>, Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, kernel@...nvz.org
Subject: Re: [PATCH memcg 0/1] false global OOM triggered by memcg-limited
 task

On Mon 18-10-21 08:07:20, Shakeel Butt wrote:
> On Mon, Oct 18, 2021 at 5:27 AM Michal Hocko <mhocko@...e.com> wrote:
> >
> > [restore the cc list]
> >
> > On Mon 18-10-21 15:14:26, Vasily Averin wrote:
> > > On 18.10.2021 14:53, Michal Hocko wrote:
> > > > On Mon 18-10-21 13:05:35, Vasily Averin wrote:
> > > >> On 18.10.2021 12:04, Michal Hocko wrote:
> > > >> Here we call try_charge_memcg() that return success and approve the allocation,
> > > >> however then we hit into kmem limit and fail the allocation.
> > > >
> > > > Just to make sure I understand this would be for the v1 kmem explicit
> > > > limit, correct?
> > >
> > > yes, I mean this limit.
> >
> > OK, thanks for the clarification. This is a known problem. Have a look
> > at I think we consider that one to 0158115f702b ("memcg, kmem: deprecate
> > kmem.limit_in_bytes"). We are reporting the deprecated and to-be removed
> > status since 2019 without any actual report sugested by the kernel
> > message. Maybe we should try and remove it and see whether that prompts
> > some pushback.
> >
> 
> Yes, I think now should be the right time to take the next step for
> deprecation of kmem limits:
> https://lore.kernel.org/all/20201118175726.2453120-1-shakeelb@google.com/

I completely forgot about your patch.  Anyway, it usually takes us years
to deprecate something so let's stick with it and consider 2 years as
years ;)

-- 
Michal Hocko
SUSE Labs