linux-kernel - Re: [PATCH v2] memcg, fsnotify: no oom-kill for remote memcg charging

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Message-ID: <20190508232042.GA1104@tower.DHCP.thefacebook.com>
Date:   Wed, 8 May 2019 23:20:51 +0000
From:   Roman Gushchin <guro@...com>
To:     Shakeel Butt <shakeelb@...gle.com>
CC:     Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>, Amir Goldstein <amir73il@...il.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "cgroups@...r.kernel.org" <cgroups@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH v2] memcg, fsnotify: no oom-kill for remote memcg charging

On Sat, May 04, 2019 at 07:52:42AM -0700, Shakeel Butt wrote:
> The commit d46eb14b735b ("fs: fsnotify: account fsnotify metadata to
> kmemcg") added remote memcg charging for fanotify and inotify event
> objects. The aim was to charge the memory to the listener who is
> interested in the events but without triggering the OOM killer.
> Otherwise there would be security concerns for the listener. At the
> time, oom-kill trigger was not in the charging path. A parallel work
> added the oom-kill back to charging path i.e. commit 29ef680ae7c2
> ("memcg, oom: move out_of_memory back to the charge path"). So to not
> trigger oom-killer in the remote memcg, explicitly add
> __GFP_RETRY_MAYFAIL to the fanotigy and inotify event allocations.
> 
> Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
> ---
> Changelog since v1:
> - Fixed usage of __GFP_RETRY_MAYFAIL flag.
> 
>  fs/notify/fanotify/fanotify.c        | 5 ++++-
>  fs/notify/inotify/inotify_fsnotify.c | 7 +++++--
>  2 files changed, 9 insertions(+), 3 deletions(-)

Hi Shakeel,

the patch looks good to me!

Reviewed-by: Roman Gushchin <guro@...com>

Thanks!