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Date: Sat, 17 Jun 2017 00:07:11 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] ahci-test failures with 'Failed to get "write"
 lock'
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: John Snow <jsnow@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>

On Fri, 06/16 10:23, Peter Maydell wrote:
> On 15 June 2017 at 17:16, John Snow <jsnow@redhat.com> wrote:
> > On 06/15/2017 11:28 AM, Dr. David Alan Gilbert wrote:
> >> Hi,
> >>   Peter noticed that there were some hangs in the ahci-test;
> >> I can reproduce them on my laptop as long as the laptop has
> >> some other load on it (a few md5sum /dev/zero's help).
> >>
> >> /x86_64/ahci/flush/migrate: qemu-system-x86_64: Failed to get "write" lock
> >> Is another process using the image?
> >> OK
> >> /x86_64/ahci/migrate/sanity: qemu-system-x86_64: Failed to get "write" lock
> >> Is another process using the image?
> >>
> >> and that hangs in sanity.
> >>
> >> That seems to be the common case, I've also had one:
> >>
> >> /x86_64/ahci/migrate/ncq/halted: qemu-system-x86_64: Failed to get "write" lock
> >> Is another process using the image?
> >> qemu-system-x86_64: /home/dgilbert/git/qemu/block/io.c:1352: bdrv_aligned_pwritev: Assertion `child->perm & BLK_PERM_WRITE' failed.
> >>
> >>
> >> Neither of these always fail.
> 
> > Haven't observed myself and I run the tests pretty frequently. I'll keep
> > an eye out. I see many similar problems in iotests for other areas, too.
> 
> If we can figure out this quickly that would be good -- it's
> causing my build tests to fail often enough that I'm a bit
> reluctant to try to merge more pull requests until we've
> squished this bug...

I have posted a patch:

[PATCH] migration: Fix race of image locking between src and dst

(You are Cc'ed)

Fam