From: Alasdair G Kergon <agk@redhat.com>
To: Vasily Averin <vvs@sw.ru>
Cc: Andrew Morton <akpm@linux-foundation.org>,
dm-devel@redhat.com, linux-kernel@vger.kernel.org,
devel@openvz.org, stable@kernel.org,
Jens Axboe <jens.axboe@oracle.com>, Milan Broz <mbroz@redhat.com>
Subject: Re: [dm-devel] Re: dm: bounce_pfn limit added
Date: Tue, 30 Oct 2007 23:26:17 +0000 [thread overview]
Message-ID: <20071030232617.GJ10006@agk.fab.redhat.com> (raw)
In-Reply-To: <20071030131138.3ba59731.akpm@linux-foundation.org>
On Tue, Oct 30, 2007 at 01:11:38PM -0700, Andrew Morton wrote:
> On Mon, 29 Oct 2007 09:31:39 +0300
> Vasily Averin <vvs@sw.ru> wrote:
> > Device mapper uses its own bounce_pfn that may differ from one on underlying
> > device. In that way dm can build incorrect requests that contain sg elements
> > greater than underlying device is able to handle.
> > This is the cause of slab corruption in i2o layer, occurred on i386 arch when
> > very long direct IO requests are addressed to dm-over-i2o device.
Interesting. When this patch was originally proposed a couple of years ago, we
did this instead:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=daef265f1590cf3e6de989d074041a280c82d58b;hp=00d6da9b4d6707b808481372537adb0fb38f99b3
) DM doesn't need to bounce bio's on its own, but the block layer defaults
) to that in blk_queue_make_request(). The lower level drivers should
) bounce ios themselves, that is what they need to do if not layered below
) dm anyways.
Alasdair
--
agk@redhat.com
next prev parent reply other threads:[~2007-10-30 23:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-29 6:31 Vasily Averin
2007-10-30 20:11 ` Andrew Morton
2007-10-30 23:26 ` Alasdair G Kergon [this message]
2007-10-31 2:01 ` [dm-devel] " Alasdair G Kergon
2007-10-31 2:11 ` Alasdair G Kergon
2007-10-31 7:13 ` Vasily Averin
2007-10-31 7:36 ` Hannes Reinecke
2007-10-31 22:00 ` Kiyoshi Ueda
2007-11-01 0:00 ` Alasdair G Kergon
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