[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <47282B1D.8030501@sw.ru>
Date: Wed, 31 Oct 2007 10:13:33 +0300
From: Vasily Averin <vvs@...ru>
To: agk@...hat.com, Andrew Morton <akpm@...ux-foundation.org>,
dm-devel@...hat.com, linux-kernel@...r.kernel.org,
devel@...nvz.org, stable@...nel.org,
Jens Axboe <jens.axboe@...cle.com>,
Milan Broz <mbroz@...hat.com>
Subject: Re: [dm-devel] Re: dm: bounce_pfn limit added
Alasdair G Kergon wrote:
> So currently we treat bounce_pfn as a property that does not need to be
> propagated through the stack.
>
> But is that the right approach?
> - Is there a blk_queue_bounce() missing either from dm or elsewhere?
> (And BTW can the bio_alloc() that lurks within lead to deadlock?)
>
> Firstly, what's going wrong?
> - What is the dm table you are using? (output of 'dmsetup table')
> - Which dm targets and with how many underlying devices?
> - Which underlying driver?
> - Is this direct I/O to the block device from userspace, or via some
> filesystem or what?
On my testnode I have 6 Gb memory (1Gb normal zone for i386 kernels),
i2o hardware and lvm over i2o.
[root@...0 ~]# dmsetup table
vzvg-vz: 0 10289152 linear 80:5 384
vzvg-vzt: 0 263127040 linear 80:5 10289536
[root@...0 ~]# cat /proc/partitions
major minor #blocks name
80 0 143374336 i2o/hda
80 1 514048 i2o/hda1
80 2 4096575 i2o/hda2
80 3 2040255 i2o/hda3
80 4 1 i2o/hda4
80 5 136721151 i2o/hda5
253 0 5144576 dm-0
253 1 131563520 dm-1
Diotest from LTP test suite with ~1Mb buffer size and files on dm-over-i2o
paritions corrupts i2o_iop0_msg_inpool slab.
I2o on this node is able to handle only requests with up to 38 segments. Device
mapper correctly creates such requests and as you know it uses
max_pfn=BLK_BOUNCE_ANY. When this request translates to underlying device, it
clones bio and cleans BIO_SEG_VALID flag.
In this way underlying device calls blk_recalc_rq_segments() to recount number
of segments. However blk_recalc_rq_segments uses bounce_pfn=BLK_BOUNCE_HIGH
taken from underlying device. As result number of segments become over than
max_hw_segments limit.
Unfortunately there is not any checks and when i2o driver handles this incorrect
request it fills the memory out of i2o_iop0_msg_inpool slab.
Thank you,
Vasily Averin
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists