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From:   Shakeel Butt <shakeelb@google.com>
Date:   Sat, 14 Jul 2018 08:38:17 -0700
Message-ID: <CALvZod57QFRVQ7kM4LSNQJACQ+dGC_otJkqK-5+i-0b53Zq5aA@mail.gmail.com>
Subject: Re: [PATCH] mm: avoid bothering interrupted task when charge memcg in softirq
To:     Yafang Shao <laoar.shao@gmail.com>
Cc:     Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        Cgroups <cgroups@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Sat, Jul 14, 2018 at 1:32 AM Yafang Shao <laoar.shao@gmail.com> wrote:
>
> try_charge maybe executed in packet receive path, which is in interrupt
> context.
> In this situation, the 'current' is the interrupted task, which may has
> no relation to the rx softirq, So it is nonsense to use 'current'.
>

Have you actually seen this occurring? I am not very familiar with the
network code but I can think of two ways try_charge() can be called
from network code. Either through kmem charging or through
mem_cgroup_charge_skmem() and both locations correctly handle
interrupt context.

Shakeel