Re: [syzbot] unregister_netdevice: waiting for DEV to become free (7)

[Dmitry Vyukov]

On Fri, 18 Nov 2022 at 12:39, syzbot
<syzbot+5e70d01ee8985ae62a3b@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    9c8774e629a1 net: eql: Use kzalloc instead of kmalloc/memset
> git tree:       net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=17bf6cc8f00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=9eb259db6b1893cf
> dashboard link: https://syzkaller.appspot.com/bug?extid=5e70d01ee8985ae62a3b
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1136d592f00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1193ae64f00000
>
> Bisection is inconclusive: the issue happens on the oldest tested release.
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=167c33a2f00000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=157c33a2f00000
> console output: https://syzkaller.appspot.com/x/log.txt?x=117c33a2f00000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+5e70d01ee8985ae62a3b@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> iwpm_register_pid: Unable to send a nlmsg (client = 2)
> infiniband syj1: RDMA CMA: cma_listen_on_dev, error -98
> unregister_netdevice: waiting for vlan0 to become free. Usage count = 2

+RDMA maintainers

There are 4 reproducers and all contain:

r0 = socket$nl_rdma(0x10, 0x3, 0x14)
sendmsg$RDMA_NLDEV_CMD_NEWLINK(...)

Also the preceding print looks related (a bug in the error handling
path there?):

infiniband syj1: RDMA CMA: cma_listen_on_dev, error -98

> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches