linux-kernel - Re: [PATCH] mm, memcg: assign shrinker

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Message-ID: <20190920132114.ofzphp53vqqjb3fs@box>
Date:   Fri, 20 Sep 2019 16:21:14 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Cyrill Gorcunov <gorcunov@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, Linux MM <linux-mm@...ck.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>
Subject: Re: [PATCH] mm, memcg: assign shrinker_map before kvfree

On Fri, Sep 20, 2019 at 03:29:07PM +0300, Cyrill Gorcunov wrote:
> Currently there is a small gap between fetching pointer, calling
> kvfree and assign its value to nil. In current callgraph it is
> not a problem (since memcg_free_shrinker_maps is running from
> memcg_alloc_shrinker_maps and mem_cgroup_css_free only) still
> this looks suspicious and we can easily eliminate the gap at all.

With this logic it will still look suspicious since you don't wait a grace
period before freeing the map.

-- 
 Kirill A. Shutemov