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Subject: Re: [PATCH memcg] memcg: prohibit unconditional exceeding the limit
 of dying tasks
To:     Vasily Averin <vvs@virtuozzo.com>
Cc:     cgroups@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Michal Hocko <mhocko@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>
References: <5b06a490-55bc-a6a0-6c85-690254f86fad@virtuozzo.com>
From:   Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Message-ID: <099aa0db-045a-e5b8-6df7-b7c3fc4d3caa@i-love.sakura.ne.jp>
Date:   Fri, 10 Sep 2021 22:04:55 +0900
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On 2021/09/10 21:39, Vasily Averin wrote:
> The kernel currently allows dying tasks to exceed the memcg limits.
> The allocation is expected to be the last one and the occupied memory
> will be freed soon.
> This is not always true because it can be part of the huge vmalloc
> allocation. Allowed once, they will repeat over and over again.
> Moreover lifetime of the allocated object can differ from
> In addition the lifetime of the dying task.

Can't we add fatal_signal_pending(current) test to vmalloc() loop?

> Multiple such allocations running concurrently can not only overuse
> the memcg limit, but can lead to a global out of memory and,
> in the worst case, cause the host to panic.
> 
> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>