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

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Message-ID: <4a30aa18-e2a2-693c-8237-b75fffac9838@virtuozzo.com>
Date:   Mon, 18 Oct 2021 22:18:53 +0300
From:   Vasily Averin <vvs@...tuozzo.com>
To:     Shakeel Butt <shakeelb@...gle.com>, Michal Hocko <mhocko@...e.com>
Cc:     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 18.10.2021 21:52, Vasily Averin wrote:
> On 18.10.2021 18:07, 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/
> 
> Are you going to push it to stable kernels too?

Btw CONFIG_MEMCG_KMEM=y is set both in RHEL8 kernels and in ubuntu 20.04 LTS kernel 5.11.0-37.