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From: tu bo <tubo@linux.vnet.ibm.com>
To: Fam Zheng <famz@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>,
	qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
	qemu-devel@nongnu.org,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	cornelia.huck@de.ibm.com
Subject: Re: [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop
Date: Thu, 17 Mar 2016 19:03:10 +0800	[thread overview]
Message-ID: <56EA8EEE.2020801@linux.vnet.ibm.com> (raw)
In-Reply-To: <20160317003906.GA23821@ad.usersys.redhat.com>


On 03/17/2016 08:39 AM, Fam Zheng wrote:
> On Wed, 03/16 14:45, Paolo Bonzini wrote:
>>
>>
>> On 16/03/2016 14:38, Christian Borntraeger wrote:
>>>> If you just remove the calls to virtio_queue_host_notifier_read, here
>>>> and in virtio_queue_aio_set_host_notifier_fd_handler, does it work
>>>> (keeping patches 2-4 in)?
>>>
>>> With these changes and patch 2-4 it does no longer locks up.
>>> I keep it running some hour to check if a crash happens.
>>>
>>> Tu Bo, your setup is currently better suited for reproducing. Can you also check?
>>
>> Great, I'll prepare a patch to virtio then sketching the solution that
>> Conny agreed with.
>>
>> While Fam and I agreed that patch 1 is not required, I'm not sure if the
>> mutex is necessary in the end.
>
> If we can fix this from the virtio_queue_host_notifier_read side, the mutex/BH
> are not necessary; but OTOH the mutex does catch such bugs, so maybe it's good
> to have it. I'm not sure about the BH.
>
> And on a hindsight I realize we don't want patches 2-3 too. Actually the
> begin/end pair won't work as expected because of the blk_set_aio_context.
>
> Let's hold on this series.
>
>>
>> So if Tu Bo can check without the virtio_queue_host_notifier_read calls,
>> and both with/without Fam's patches, it would be great.
>
> Tu Bo, only with/withoug patch 4, if you want to check. Sorry for the noise.
>
1. without the virtio_queue_host_notifier_read calls,  without patch 4

crash happens very often,

(gdb) bt
#0  bdrv_co_do_rw (opaque=0x0) at block/io.c:2172
#1  0x000002aa165da37e in coroutine_trampoline (i0=<optimized out>, 
i1=1812051552) at util/coroutine-ucontext.c:79
#2  0x000003ff7dd5150a in __makecontext_ret () from /lib64/libc.so.6


2. without the virtio_queue_host_notifier_read calls, with patch 4

crash happens very often,

(gdb) bt
#0  bdrv_co_do_rw (opaque=0x0) at block/io.c:2172
#1  0x000002aa39dda43e in coroutine_trampoline (i0=<optimized out>, 
i1=-1677715600) at util/coroutine-ucontext.c:79
#2  0x000003ffab6d150a in __makecontext_ret () from /lib64/libc.so.6


> Thanks,
> Fam
>

  reply	other threads:[~2016-03-17 11:06 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-16 10:10 [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop Fam Zheng
2016-03-16 10:10 ` [Qemu-devel] [PATCH 1/4] block: Use drained section in bdrv_set_aio_context Fam Zheng
2016-03-16 10:27   ` Paolo Bonzini
2016-03-16 10:51     ` Fam Zheng
2016-03-16 10:10 ` [Qemu-devel] [PATCH 2/4] block-backend: Introduce blk_drained_begin/end Fam Zheng
2016-03-16 10:10 ` [Qemu-devel] [PATCH 3/4] virtio-blk: Use blk_drained_begin/end around dataplane stop Fam Zheng
2016-03-16 10:10 ` [Qemu-devel] [PATCH 4/4] virtio-blk: Clean up start/stop with mutex and BH Fam Zheng
2016-03-17 15:00   ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2016-03-17 15:07     ` Paolo Bonzini
2016-03-22 12:52       ` Fam Zheng
2016-03-22 18:05         ` Paolo Bonzini
2016-03-23  8:10           ` Cornelia Huck
2016-03-23  9:08             ` Paolo Bonzini
2016-03-23  9:12               ` Christian Borntraeger
2016-03-24  8:19                 ` tu bo
2016-03-24  8:32                   ` Cornelia Huck
2016-03-24  8:47                     ` Cornelia Huck
2016-03-24  9:31                       ` Cornelia Huck
2016-03-16 10:28 ` [Qemu-devel] [PATCH 0/4] Tweaks around virtio-blk start/stop Paolo Bonzini
2016-03-16 10:49   ` Christian Borntraeger
2016-03-16 11:09     ` Paolo Bonzini
2016-03-16 11:24       ` Christian Borntraeger
2016-03-16 12:55         ` Paolo Bonzini
2016-03-16 13:38           ` Christian Borntraeger
2016-03-16 13:45             ` Paolo Bonzini
2016-03-17  0:39               ` Fam Zheng
2016-03-17 11:03                 ` tu bo [this message]
2016-03-21 10:57                   ` Fam Zheng
2016-03-21 11:15                     ` Cornelia Huck
2016-03-21 12:45                       ` Fam Zheng
2016-03-21 13:02                         ` Cornelia Huck
2016-03-21 23:45                           ` Fam Zheng
2016-03-22  8:06                             ` Cornelia Huck
2016-03-22  7:10                     ` tu bo
2016-03-22  7:18                       ` Fam Zheng
2016-03-22  9:07                         ` Cornelia Huck
2016-03-22  9:46                           ` Paolo Bonzini
2016-03-22 11:59                             ` Cornelia Huck
2016-03-22 12:11                               ` Paolo Bonzini
2016-03-22 12:54                                 ` Cornelia Huck
2016-03-17 12:22             ` tu bo
2016-03-17 12:39               ` Christian Borntraeger
2016-03-17 13:02                 ` Cornelia Huck
2016-03-17 15:02                 ` Paolo Bonzini
2016-03-17 15:07                   ` Christian Borntraeger
2016-03-17 15:15                   ` Christian Borntraeger
2016-03-17 15:16                     ` Christian Borntraeger
2016-03-17 16:08                       ` Christian Borntraeger
2016-03-18 15:03                         ` Paolo Bonzini
2016-03-21  9:42                           ` Fam Zheng
2016-03-21 11:10                             ` Christian Borntraeger
2016-03-21 12:17                             ` Cornelia Huck
2016-03-21 13:47                           ` TU BO
2016-03-21 13:54                             ` Paolo Bonzini
2016-03-21 14:19                               ` Cornelia Huck
2016-03-22  0:31                                 ` Fam Zheng
2016-03-16 11:32       ` Cornelia Huck
2016-03-16 11:48         ` Paolo Bonzini
2016-03-16 11:56           ` Cornelia Huck
2016-03-16 11:59             ` Paolo Bonzini
2016-03-16 12:22               ` Cornelia Huck
2016-03-16 12:32                 ` Paolo Bonzini
2016-03-16 12:42                   ` Cornelia Huck
2016-03-16 12:49                     ` Paolo Bonzini
2016-03-16 13:04                       ` Cornelia Huck
2016-03-16 13:10                         ` Paolo Bonzini
2016-03-16 13:14                           ` Cornelia Huck
2016-03-16 13:15                             ` Paolo Bonzini
2016-03-16 11:52         ` Cornelia Huck
2016-03-16 11:54           ` Paolo Bonzini

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