linux-kernel - Re: [syzbot] [kvm?] [net?] [virt?] INFO: task hung in __vhost_worker

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Message-ID: <fd77ljndgwznty4e45t7o55sbyfdlxfl7otly5ib7mjlnsxcwb@ve45z34reswm>
Date: Thu, 27 Mar 2025 12:21:02 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Mike Christie <michael.christie@...cle.com>
Cc: "Michael S. Tsirkin" <mst@...hat.com>, 
	Sean Christopherson <seanjc@...gle.com>, syzbot <syzbot+7f3bbe59e8dd2328a990@...kaller.appspotmail.com>, 
	eperezma@...hat.com, jasowang@...hat.com, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, syzkaller-bugs@...glegroups.com, 
	virtualization@...ts.linux.dev, oleg@...hat.com, ebiederm@...ssion.com, stefanha@...hat.com, 
	brauner@...nel.org
Subject: Re: [syzbot] [kvm?] [net?] [virt?] INFO: task hung in
 __vhost_worker_flush

On Mon, Aug 19, 2024 at 10:19:44AM -0500, Mike Christie wrote:
>On 8/16/24 1:17 PM, Michael S. Tsirkin wrote:
>> On Fri, Aug 16, 2024 at 11:10:32AM -0700, Sean Christopherson wrote:
>>> On Fri, Aug 16, 2024, syzbot wrote:
>>>>> On Wed, May 29, 2024, syzbot wrote:
>>>>>> Hello,
>>>>>>
>>>>>> syzbot found the following issue on:
>>>>>>
>>>>>> HEAD commit:    9b62e02e6336 Merge tag 'mm-hotfixes-stable-2024-05-25-09-1..
>>>>>> git tree:       upstream
>>>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=16cb0eec980000
>>>>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=3e73beba72b96506
>>>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=7f3bbe59e8dd2328a990
>>>>>> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
>>>>>>
>>>>>> Unfortunately, I don't have any reproducer for this issue yet.
>>>>>>
>>>>>> Downloadable assets:
>>>>>> disk image: https://storage.googleapis.com/syzbot-assets/61b507f6e56c/disk-9b62e02e.raw.xz
>>>>>> vmlinux: https://storage.googleapis.com/syzbot-assets/6991f1313243/vmlinux-9b62e02e.xz
>>>>>> kernel image: https://storage.googleapis.com/syzbot-assets/65f88b96d046/bzImage-9b62e02e.xz
>>>>>>
>>>>>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>>>>>> Reported-by: syzbot+7f3bbe59e8dd2328a990@...kaller.appspotmail.com
>>>>>
>>>>> #syz unset kvm
>>>>
>>>> The following labels did not exist: kvm
>>>
>>> Hrm, looks like there's no unset for a single subsytem, so:
>>>
>>> #syz set subsystems: net,virt
>>
>> Must be this patchset:
>>
>> https://lore.kernel.org/all/20240316004707.45557-1-michael.christie@oracle.com/
>>
>> but I don't see anything obvious there to trigger it, and it's not
>> reproducible yet...
>>
>
>Sorry, I missed the original post from May.
>
>I'm trying to replicate it now, but am not seeing it.
>
>The only time I've seen something similar is when the flush is actually waiting
>for a work item to complete, but I don't think the sysbot tests that for vsock.
>So, I think I'm hitting a race that I'm just not seeing yet. I'm just getting
>back from vacation, and will do some more testing/review this week.

Hi Mike,
looking at the syzbot virt monthly report I saw this issuse still open 
and with crashes:

   https://syzkaller.appspot.com/bug?extid=7f3bbe59e8dd2328a990

Have you had a chance to take a look?

Thanks,
Stefano