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From:   Waiman Long <llong@redhat.com>
Subject: Re: [RFC PATCH] mm/oom_kill: allow oom kill allocating task for
 non-global case
To:     Michal Hocko <mhocko@suse.com>, Aaron Tomlin <atomlin@redhat.com>
Cc:     linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz,
        llong@redhat.com, linux-kernel@vger.kernel.org
References: <20210607163103.632681-1-atomlin@redhat.com>
 <YL5tBQ3utMzUkHF3@dhcp22.suse.cz>
Message-ID: <8a6b57d1-b8dd-bf67-92c8-0421623f54ea@redhat.com>
Date:   Mon, 7 Jun 2021 15:26:00 -0400
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On 6/7/21 3:01 PM, Michal Hocko wrote:
> On Mon 07-06-21 17:31:03, Aaron Tomlin wrote:
>> At the present time, in the context of memcg OOM, even when
>> sysctl_oom_kill_allocating_task is enabled/or set, the "allocating"
>> task cannot be selected, as a target for the OOM killer.
>>
>> This patch removes the restriction entirely.
> This is a global oom policy not a memcg specific one so a historical
> behavior would change. So I do not think we can change that. The policy
> can be implemented on the memcg level but this would require a much more
> detailed explanation of the usecase and the semantic (e.g. wrt.
> hierarchical behavior etc).

Maybe we can extend the meaning of oom_kill_allocating_task such that 
memcg OOM killing of allocating task is only enabled when bit 1 is set. 
So if an existing application just set oom_kill_allocating_task to 1, it 
will not be impacted.

Cheers,
Longman