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Date: Fri, 20 Aug 2010 05:19:04 -0400
From: Christoph Hellwig <hch@infradead.org>
To: Wu Fengguang <fengguang.wu@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>, Jeff Layton <jlayton@redhat.com>,
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        linux-mm@kvack.org, Chris Mason <chris.mason@oracle.com>,
        Jens Axboe <jens.axboe@oracle.com>
Subject: Re: why are WB_SYNC_NONE COMMITs being done with FLUSH_SYNC set ?
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References: <20100819101525.076831ad@barsoom.rdu.redhat.com>
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On Fri, Aug 20, 2010 at 07:55:53AM +0800, Wu Fengguang wrote:
> Since migration and pageout still set nonblocking for ->writepage, we
> may keep them in the near future, until VM does not start IO on itself.

Why does pageout() and memory migration need to be even more
non-blocking than the already non-blockig WB_SYNC_NONE writeout?