From: Theodore Ts'o <tytso@mit.edu>
Subject: Re: page eviction from the buddy cache
Date: Sat, 20 Apr 2013 19:57:18 -0400
Message-ID: <20130420235718.GA28789@thunk.org>
References: <51504A40.6020604@ya.ru>
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 <51730619.3030204@fastmail.fm>
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Cc: Alexey Lyahkov <alexey.lyashkov@gmail.com>,
	Will Huck <will.huckk@gmail.com>, Hugh Dickins <hughd@google.com>,
	Andrew Perepechko <anserper@ya.ru>, linux-ext4@vger.kernel.org,
	akpm@linux-foundation.org, linux-mm@kvack.org, mgorman@suse.de
To: Bernd Schubert <bernd.schubert@fastmail.fm>
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On Sat, Apr 20, 2013 at 11:18:17PM +0200, Bernd Schubert wrote:
> Alex, Andrew,
> 
> did you notice the patch Ted just sent?
> ("ext4: mark all metadata I/O with REQ_META")

This patch was sent to fix another issue that was brought up at Linux
Storage, Filesystem, and MM workshop.  I did bring up this issue with
Mel Gorman while at LSF/MM, and as a result, tThe mm folks are going
to look into making mark_page_accessed() do the right thing, or
perhaps provide us with new interface.  The problem with forcing the
page to be marked as activated is this would cause a TLB flush, which
would be pointless since this these buddy bitmap pages aren't actually
mapped in anywhere.

						- Ted

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