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From: Jason Gunthorpe <jgg@ziepe.ca>
To: syzbot <syzbot+4088ed905e4ae2b0e13b@syzkaller.appspotmail.com>
Cc: dledford@redhat.com, kamalheib1@gmail.com, leon@kernel.org,
	linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org,
	netdev@vger.kernel.org, parav@mellanox.com,
	syzkaller-bugs@googlegroups.com
Subject: Re: WARNING in ib_unregister_device_queued
Date: Mon, 27 Apr 2020 21:10:34 -0300	[thread overview]
Message-ID: <20200428001034.GQ26002@ziepe.ca> (raw)
In-Reply-To: <000000000000aa012505a431c7d9@google.com>

On Sun, Apr 26, 2020 at 06:43:13AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    b9663b7c net: stmmac: Enable SERDES power up/down sequence
> git tree:       net
> console output: https://syzkaller.appspot.com/x/log.txt?x=166bf717e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5d351a1019ed81a2
> dashboard link: https://syzkaller.appspot.com/bug?extid=4088ed905e4ae2b0e13b
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+4088ed905e4ae2b0e13b@syzkaller.appspotmail.com
> 
> rdma_rxe: ignoring netdev event = 10 for netdevsim0
> infiniband  yz2: set down
> WARNING: CPU: 0 PID: 22753 at drivers/infiniband/core/device.c:1565 ib_unregister_device_queued+0x122/0x160 drivers/infiniband/core/device.c:1565

The only thing I can think of for this is that ib_register_driver()
is racing with __ib_unregister_device() and took the special error
unwind.

I suspect this is not a bug, but over complexity triggering a
pre-condition WARN_ON..

Maybe the solution is to swap the dealloc_driver = NULL for some other flag.

Jason

  reply	other threads:[~2020-04-28  0:10 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-26 13:43 syzbot
2020-04-28  0:10 ` Jason Gunthorpe [this message]
     [not found] ` <20200428041956.5704-1-hdanton@sina.com>
2020-04-28 12:31   ` Jason Gunthorpe

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