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Date: Tue, 26 Jun 2018 14:57:24 -0400
From: Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH 1/2] fs: fsnotify: account fsnotify metadata to kmemcg
Message-ID: <20180626185724.GA3958@cmpxchg.org>
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To: Shakeel Butt <shakeelb@google.com>
Cc: Amir Goldstein <amir73il@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Michal Hocko <mhocko@kernel.org>, Vladimir Davydov <vdavydov.dev@gmail.com>, Jan Kara <jack@suse.com>, Greg Thelen <gthelen@google.com>, Roman Gushchin <guro@fb.com>, Alexander Viro <viro@zeniv.linux.org.uk>, LKML <linux-kernel@vger.kernel.org>, Cgroups <cgroups@vger.kernel.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Linux MM <linux-mm@kvack.org>, Jan Kara <jack@suse.cz>

On Tue, Jun 26, 2018 at 11:00:53AM -0700, Shakeel Butt wrote:
> On Mon, Jun 25, 2018 at 10:49 PM Amir Goldstein <amir73il@gmail.com> wrote:
> >
> ...
> >
> > The verb 'unuse' takes an argument memcg and 'uses' it - too weird.
> > You can use 'override'/'revert' verbs like override_creds or just call
> > memalloc_use_memcg(old_memcg) since there is no reference taken
> > anyway in use_memcg and no reference released in unuse_memcg.
> >
> > Otherwise looks good to me.
> >
> 
> Thanks for your feedback. Just using memalloc_use_memcg(old_memcg) and
> ignoring the return seems more simple. I will wait for feedback from
> other before changing anything.

We're not nesting calls to memalloc_use_memcg(), right? So we don't
have to return old_memcg and don't have to pass anything to unuse, it
can always set current->active_memcg to NULL.