From: Mike Snitzer <snitzer@redhat.com>
To: axboe@kernel.dk
Cc: linux-kernel@vger.kernel.org, martin.petersen@oracle.com,
hch@infradead.org, mst@redhat.com, rusty@rustcorp.com.au,
dm-devel@redhat.com
Subject: Re: virtio_blk: fix defaults for max_hw_sectors and max_segment_size
Date: Thu, 20 Nov 2014 20:59:41 -0500 [thread overview]
Message-ID: <20141121015941.GC2287@redhat.com> (raw)
In-Reply-To: <20141120190058.GA31214@redhat.com>
On Thu, Nov 20 2014 at 2:00pm -0500,
Mike Snitzer <snitzer@redhat.com> wrote:
> virtio_blk incorrectly established -1U as the default for these
> queue_limits. Set these limits to sane default values to avoid crashing
> the kernel. But the virtio-blk protocol should probably be extended to
> allow proper stacking of the disk's limits from the host.
>
> This change fixes a crash that was reported when virtio-blk was used to
> test linux-dm.git commit 604ea90641b4 ("dm thin: adjust max_sectors_kb
> based on thinp blocksize") that will initially set max_sectors to
> max_hw_sectors and then rounddown to the first power-of-2 factor of the
> DM thin-pool's blocksize. Basically that commit assumes drivers don't
> suck when establishing max_hw_sectors so it acted like a canary in the
> coal mine.
I have changed that DM thinp code to not be so fragile with this
follow-on fix:
https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=dm-for-3.19&id=971ab7029b61ec10e0765bfb96331448ce5c3094
> In the case of a DM thin-pool built ontop of virtio-blk data device
> these are the insane limits that were established for the DM thin-pool:
>
> # cat /sys/block/dm-6/queue/max_sectors_kb
> 1073741824
> # cat /sys/block/dm-6/queue/max_hw_sectors_kb
> 2147483647
>
> by stacking the virtio-blk device's limits:
>
> # cat /sys/block/vdb/queue/max_sectors_kb
> 512
> # cat /sys/block/vdb/queue/max_hw_sectors_kb
> 2147483647
>
> Attempting to mkfs.xfs against a thin device from this thin-pool quickly
> resulted in fs/direct-io.c:dio_send_cur_page()'s BUG_ON.
But virtio_blk really must be fixed. I'll post v2 of this patch with a
revised header that skips all the references to DM thinp, etc.
next prev parent reply other threads:[~2014-11-21 2:00 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-20 19:00 [PATCH] virtio_blk: fix defaults for max_hw_sectors and max_segment_size Mike Snitzer
2014-11-20 20:30 ` Michael S. Tsirkin
2014-11-20 21:15 ` Mike Snitzer
2014-11-26 5:58 ` Rusty Russell
2014-11-26 14:10 ` Mike Snitzer
2014-11-21 1:59 ` Mike Snitzer [this message]
2014-11-21 2:11 ` [PATCH v2] " Mike Snitzer
2014-11-21 9:54 ` [PATCH] " Christoph Hellwig
2014-11-21 15:49 ` Mike Snitzer
2014-11-26 19:48 ` Jens Axboe
2014-11-26 20:51 ` Mike Snitzer
2014-11-26 20:54 ` Jens Axboe
2014-11-26 21:51 ` Mike Snitzer
2014-11-26 21:53 ` Jens Axboe
2014-11-26 23:00 ` Mike Snitzer
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20141121015941.GC2287@redhat.com \
--to=snitzer@redhat.com \
--cc=axboe@kernel.dk \
--cc=dm-devel@redhat.com \
--cc=hch@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=martin.petersen@oracle.com \
--cc=mst@redhat.com \
--cc=rusty@rustcorp.com.au \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).