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Date:   Tue, 19 Oct 2021 10:49:37 +0200
From:   Michal Hocko <mhocko@suse.com>
To:     Vasily Averin <vvs@virtuozzo.com>
Cc:     Johannes Weiner <hannes@cmpxchg.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Roman Gushchin <guro@fb.com>,
        Uladzislau Rezki <urezki@gmail.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Shakeel Butt <shakeelb@google.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        cgroups@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, kernel@openvz.org
Subject: Re: [PATCH memcg 0/1] false global OOM triggered by memcg-limited
 task
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On Tue 19-10-21 09:30:18, Vasily Averin wrote:
[...]
> With my patch ("memcg: prohibit unconditional exceeding the limit of dying tasks") try_charge_memcg() can fail:
> a) due to fatal signal
> b) when mem_cgroup_oom -> mem_cgroup_out_of_memory -> out_of_memory() returns false (when select_bad_process() found nothing)
> 
> To handle a) we can follow to your suggestion and skip excution of out_of_memory() in pagefault_out_of memory()
> To handle b) we can go to retry: if mem_cgroup_oom() return OOM_FAILED.

How is b) possible without current being killed? Do we allow remote
charging?

> However all these cases can be successfully handled by my new patch
> "memcg: prevent false global OOM triggered by memcg limited task"
> and I think it is better solution.

I have already replied to your approach in other email. Sorry our
replies have crossed.
-- 
Michal Hocko
SUSE Labs