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From: Rusty Russell <rusty@rustcorp.com.au>
To: Mike Snitzer <snitzer@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>
Cc: axboe@kernel.dk, linux-kernel@vger.kernel.org,
	martin.petersen@oracle.com, hch@infradead.org,
	dm-devel@redhat.com
Subject: Re: virtio_blk: fix defaults for max_hw_sectors and max_segment_size
Date: Wed, 26 Nov 2014 16:28:27 +1030	[thread overview]
Message-ID: <87bnnuy03g.fsf@rustcorp.com.au> (raw)
In-Reply-To: <20141120211521.GA846@redhat.com>

Mike Snitzer <snitzer@redhat.com> writes:
> On Thu, Nov 20 2014 at  3:30pm -0500,
> Michael S. Tsirkin <mst@redhat.com> wrote:
>
>> On Thu, Nov 20, 2014 at 02:00:59PM -0500, Mike Snitzer 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.
> ...
>> > 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.
>> 
>> Why exactly does it BUG_ON?
>> Did some memory allocation fail?
>
> No idea, kernel log doesn't say.. all it has is "kernel BUG" pointing to
> fs/direct-io.c:dio_send_cur_page()'s BUG_ON.
>
> I could dig deeper on _why_ but honestly, there really isn't much point.

There is *always* a point in understanding the code you are modifying.

> virtio-blk doesn't get to live in fantasy-land just because it happens
> to think it is limitless.

Calm down please.

We don't have a sector limit.  We have a segment limit, which is set
above this line.

Cheers,
Rusty.

  reply	other threads:[~2014-11-26  6:22 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 [this message]
2014-11-26 14:10       ` Mike Snitzer
2014-11-21  1:59 ` Mike Snitzer
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

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