Re: [Qemu-devel] [Qemu-block] [BUG] qed_aio_write_alloc: Assertion `s->allocating_acb == NULL' failed.

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Fri, Jun 29, 2018 at 10:35:28PM +0200, Kevin Wolf wrote:
> Am 29.06.2018 um 22:16 hat Eric Blake geschrieben:
> > On 06/29/2018 03:07 PM, John Snow wrote:
> > > CC Qemu Block; looks like QED is a bit busted.
> > > 
> > > On 06/27/2018 10:25 AM, Quytelda Kahja wrote:
> > > > Hello all,
> > > > I wanted to submit a bug report in the tracker, but it seem to require
> > > > an Ubuntu One account, which I'm having trouble with, so I'll just
> > > > give it here and hopefully somebody can make use of it.  The issue
> > > > seems to be in an experimental format, so it's likely not very
> > > > consequential anyway.
> > 
> > Analysis in another thread may be relevant:
> > 
> > https://lists.gnu.org/archive/html/qemu-devel/2018-06/msg08963.html
> 
> The assertion there was:
> 
> qemu-system-x86_64: block.c:3434: bdrv_replace_node: Assertion `!atomic_read(&to->in_flight)' failed.
> 
> Which quite clearly pointed to a drain bug. This one, however, doesn't
> seem to be related to drain, so I think it's probably a different bug.

Maybe there was a CoQueue regression in QEMU 2.10, 2.11, or 2.12.

My own commit c40a2545700e9ad2ef67d5972484bbee4c83b2a6 ("coroutine:
avoid co_queue_wakeup recursion") from QEMU 2.12.0 would be a good place
to start.  I wonder if it fails before this commit.

git-bisect(1) could be used to track down the commit that broken qed,
although bisecting using a BSD installer sounds time-consuming.

Stefan

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