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Date: Wed, 11 Feb 2015 17:30:30 -0500
From: Tejun Heo <tj@kernel.org>
Subject: Re: [RFC] Making memcg track ownership per address_space or anon_vma
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To: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Greg Thelen <gthelen@google.com>, Konstantin Khlebnikov <khlebnikov@yandex-team.ru>, Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.cz>, Cgroups <cgroups@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Jan Kara <jack@suse.cz>, Dave Chinner <david@fromorbit.com>, Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@infradead.org>, Li Zefan <lizefan@huawei.com>, Hugh Dickins <hughd@google.com>

Hello,

On Thu, Feb 12, 2015 at 02:15:29AM +0400, Konstantin Khlebnikov wrote:
> Well, ok. Even if shared writes are rare whey should be handled somehow
> without relying on kupdate-like writeback. If memcg has a lot of dirty pages

This only works iff we consider those cases to be marginal enough to
be handle them in a pretty ghetto way.

> but their inodes are accidentially belong to wrong wb queues when tasks in
> that memcg shouldn't stuck in balance-dirty-pages until somebody outside
> acidentially writes this data. That's all what I wanted to say.

But, right, yeah, corner cases around this could be nasty if writeout
interval is set really high.  I don't think it matters for the default
5s interval at all.  Maybe what we need is queueing a delayed per-wb
work w/ the default writeout interval when dirtying a foreign inode.
I'll think more about it.

Thanks.

-- 
tejun

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