linux-kernel - Re: [PATCH] mm: avoid bothering interrupted task when charge memcg in softirq

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Date:   Sat, 14 Jul 2018 08:38:17 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Yafang Shao <laoar.shao@...il.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Cgroups <cgroups@...r.kernel.org>, Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: avoid bothering interrupted task when charge memcg in softirq

On Sat, Jul 14, 2018 at 1:32 AM Yafang Shao <laoar.shao@...il.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