Date: Mon, 19 Jul 2010 10:20:51 -0400
From: Christoph Hellwig <hch@infradead.org>
To: Mel Gorman <mel@csn.ul.ie>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-mm@kvack.org, Dave Chinner <david@fromorbit.com>,
        Chris Mason <chris.mason@oracle.com>, Nick Piggin <npiggin@suse.de>,
        Rik van Riel <riel@redhat.com>, Johannes Weiner <hannes@cmpxchg.org>,
        Christoph Hellwig <hch@infradead.org>,
        Wu Fengguang <fengguang.wu@intel.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH 6/8] fs,xfs: Allow kswapd to writeback pages
Message-ID: <20100719142051.GC12510@infradead.org>
References: <1279545090-19169-1-git-send-email-mel@csn.ul.ie>
 <1279545090-19169-7-git-send-email-mel@csn.ul.ie>
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On Mon, Jul 19, 2010 at 02:11:28PM +0100, Mel Gorman wrote:
> As only kswapd and memcg are writing back pages, there should be no
> danger of overflowing the stack. Allow the writing back of dirty pages
> in xfs from the VM.

As pointed out during the discussion on one of your previous post memcg
does pose a huge risk of stack overflows.  In the XFS tree we've already
relaxed the check to allow writeback from kswapd, and until the memcg
situation we'll need to keep that check.

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