From: Eric Blake <eblake@redhat.com>
To: Sergio Lopez <slp@redhat.com>, qemu-block@nongnu.org
Cc: kwolf@redhat.com, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] nbd/server: attach client channel to the export's AioContext
Date: Wed, 11 Sep 2019 17:03:52 -0500 [thread overview]
Message-ID: <5c1488f6-00ed-9d28-f544-a198f2fada94@redhat.com> (raw)
In-Reply-To: <6755b34b-b412-9e63-8d25-b7662d0d3860@redhat.com>
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On 9/11/19 4:33 PM, Eric Blake wrote:
> I tried to test this patch, but even with it applied, I still got an
> aio-context crasher by attempting an nbd-server-start, nbd-server-add,
> nbd-server-stop (intentionally skipping the nbd-server-remove step) on a
> domain using iothreads, with a backtrace of:
The crash also reproduces with nbd-server-remove instead of
nbd-server-stop. Both QMP commands eventually call into the
blk_remove_bs() that calls the fatal blk_drain(). So libvirt can't work
around the bug merely by adding an nbd-server-remove step.
>
> #0 0x00007ff09d070e35 in raise () from target:/lib64/libc.so.6
> #1 0x00007ff09d05b895 in abort () from target:/lib64/libc.so.6
> #2 0x000055dd03b9ab86 in error_exit (err=1, msg=0x55dd03d59fb0
> <__func__.15769> "qemu_mutex_unlock_impl")
> at util/qemu-thread-posix.c:36
> #3 0x000055dd03b9adcf in qemu_mutex_unlock_impl (mutex=0x55dd062d5090,
> file=0x55dd03d59041 "util/async.c",
> line=523) at util/qemu-thread-posix.c:96
> #4 0x000055dd03b93433 in aio_context_release (ctx=0x55dd062d5030) at
> util/async.c:523
> #5 0x000055dd03ac421b in bdrv_do_drained_begin (bs=0x55dd0673a2d0,
> recursive=false, parent=0x0,
> ignore_bds_parents=false, poll=true) at block/io.c:428
> #6 0x000055dd03ac4299 in bdrv_drained_begin (bs=0x55dd0673a2d0) at
> block/io.c:434
> #7 0x000055dd03aafb54 in blk_drain (blk=0x55dd06a3ec40) at
> block/block-backend.c:1605
> #8 0x000055dd03aae054 in blk_remove_bs (blk=0x55dd06a3ec40) at
> block/block-backend.c:800
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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next prev parent reply other threads:[~2019-09-11 22:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 16:15 [Qemu-devel] [PATCH] nbd/server: attach client channel to the export's AioContext Sergio Lopez
2019-09-11 17:21 ` Eric Blake
2019-09-11 21:33 ` Eric Blake
2019-09-11 22:03 ` Eric Blake [this message]
2019-09-12 6:37 ` Sergio Lopez
2019-09-16 21:11 ` Eric Blake
2019-09-12 8:14 ` Kevin Wolf
2019-09-12 10:30 ` Sergio Lopez
2019-09-12 11:31 ` Kevin Wolf
2019-09-16 22:30 ` Eric Blake
2019-09-12 8:23 ` Kevin Wolf
2019-09-12 10:13 ` Sergio Lopez
2019-09-12 10:25 ` Kevin Wolf
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