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References: <20210315234100.64307-1-hannes@cmpxchg.org>
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From:   Shakeel Butt <shakeelb@google.com>
Date:   Mon, 15 Mar 2021 16:58:49 -0700
Message-ID: <CALvZod7VzxYc4Kz0WPHWt74YMopi9XrCu4CKtEGTRKxXPSP=8w@mail.gmail.com>
Subject: Re: [PATCH] mm: memcontrol: switch to rstat fix
To:     Johannes Weiner <hannes@cmpxchg.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>, Roman Gushchin <guro@fb.com>,
        Tejun Heo <tj@kernel.org>,
        =?UTF-8?Q?Michal_Koutn=C3=BD?= <mkoutny@suse.com>,
        Cgroups <cgroups@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Kernel Team <kernel-team@fb.com>
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On Mon, Mar 15, 2021 at 4:41 PM Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> Fix a sleep in atomic section problem: wb_writeback() takes a spinlock
> and calls wb_over_bg_thresh() -> mem_cgroup_wb_stats, but the regular
> rstat flushing function called from in there does lockbreaking and may
> sleep. Switch to the atomic variant, cgroup_rstat_irqsafe().
>
> To be consistent with other memcg flush calls, but without adding
> another memcg wrapper, inline and drop memcg_flush_vmstats() instead.
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Reviewed-by: Shakeel Butt <shakeelb@google.com>