Re: unregister_netdevice: waiting for DEV to become free (2)

[Lukas Bulwahn]

On Thu, Nov 28, 2019 at 10:56 AM Tetsuo Handa
<penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello people involved in commit a3e23f719f5c4a38 ("net-sysfs: call dev_hold if kobject_init_and_add success")
> and commit b8eb718348b8fb30 ("net-sysfs: Fix reference count leak in rx|netdev_queue_add_kobject").
>
> syzbot is reporting that unregister_netdevice() hangs due to underflowing
> device refcount when kobject_init_and_add() failed due to -ENOMEM.
>

Tetsuo, would you happen to have a C reproducer program that creates
the trace you reported?

I could not quickly find one that by the date would fit to when we
included our change on this syzbot page:
https://syzkaller.appspot.com/bug?id=bae9a2236bfede42cf3d219e6bf6740c583568a4

Jouni, can you please follow up on this report.

Thanks.

Lukas