Date: Wed, 23 Jul 2014 17:19:09 +0200
From: Michal Hocko <mhocko@suse.cz>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>, Tejun Heo <tj@kernel.org>,
        Vladimir Davydov <vdavydov@parallels.com>, linux-mm@kvack.org,
        cgroups@vger.kernel.org,
        Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [patch 13/13] mm: memcontrol: rewrite uncharge API
Message-ID: <20140723151909.GC16721@dhcp22.suse.cz>
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On Wed 23-07-14 11:06:08, Johannes Weiner wrote:
> On Wed, Jul 23, 2014 at 04:38:47PM +0200, Michal Hocko wrote:
[...]
> > OK, thanks for the clarification. I had this feeling but couldn't wrap
> > my head around the indirection of the code.
> > 
> > It seems that checkig PageCgroupUsed(new) and bail out early in
> > mem_cgroup_migrate should just work, no?
> 
> If the new page is already charged as page cache, we could just drop
> the call to mem_cgroup_migrate() altogether.

Yeah, it is just that we do not want to do all the
page->page_cgroup->PageCgroupUsed thing in replace_page_cache_page.

-- 
Michal Hocko
SUSE Labs
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