Re: [syzbot] [netfs?] INFO: task hung in netfs_unbuffered_write_iter

From: Oleg Nesterov
Date: Fri Mar 28 2025 - 13:01:14 EST


Dear syzbot,

On 03/28, syzbot wrote:
>
> syzbot has tested the proposed patch and the reproducer did not trigger any issue:
>
> Reported-by: syzbot+62262fdc0e01d99573fc@xxxxxxxxxxxxxxxxxxxxxxxxx
> Tested-by: syzbot+62262fdc0e01d99573fc@xxxxxxxxxxxxxxxxxxxxxxxxx

Thanks. so the previous

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
unregister_netdevice: waiting for DEV to become free

unregister_netdevice: waiting for batadv0 to become free. Usage count = 3

report suggests that upstream/master has another/unrelated issue(s).

As for the patches from me or Prateek (thanks again!), I think that
the maintainers should take a look.

But at this point I am mostly confident that the bisected commit aaec5a95d5961
("pipe_read: don't wake up the writer if the pipe is still full") is innocent,
it just reveals yet another problem.

I guess (I hope ;) Prateek agrees.

Oleg.