unregister_netdevice: waiting for DEV to become free (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 14b58326 Linux 4.14.193
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1142485e900000
kernel config: https://syzkaller.appspot.com/x/.config?x=68ef0287ccbc3b42
dashboard link: https://syzkaller.appspot.com/bug?extid=2c288da629ec1a28f5e5
compiler: gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2c288d...@syzkaller.appspotmail.com

bond0 (unregistering): Released all slaves
NOHZ: local_softirq_pending 08
Bluetooth: hci3 command 0x0409 tx timeout
Bluetooth: hci3 command 0x041b tx timeout
Bluetooth: hci3 command 0x040f tx timeout
unregister_netdevice: waiting for lo to become free. Usage count = 1
Bluetooth: hci3 command 0x0419 tx timeout
NOHZ: local_softirq_pending 08


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 96afcb20 Linux 4.14.233
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16430553d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=3c01be598d99fad6
dashboard link: https://syzkaller.appspot.com/bug?extid=2c288da629ec1a28f5e5
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=132b0bd7d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2c288d...@syzkaller.appspotmail.com

syz-executor.2 (7997) used greatest stack depth: 24848 bytes left
Bluetooth: hci0 command 0x0409 tx timeout
Bluetooth: hci0 command 0x041b tx timeout
Bluetooth: hci0 command 0x040f tx timeout
unregister_netdevice: waiting for ip6gre0 to become free. Usage count = -1
Bluetooth: hci0 command 0x0419 tx timeout

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 96afcb20 Linux 4.14.233
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11953fb3d00000

kernel config: https://syzkaller.appspot.com/x/.config?x=3c01be598d99fad6
dashboard link: https://syzkaller.appspot.com/bug?extid=2c288da629ec1a28f5e5

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15dabf53d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13997535d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2c288d...@syzkaller.appspotmail.com

syz-executor925[28115]: segfault at 0 ip (null) sp 00007fdff48ec328 error 14 in syz-executor925865502[400000+1000]
unregister_netdevice: waiting for ip6gre0 to become free. Usage count = -1
syz-executor925[29234]: segfault at 0 ip (null) sp 00007fdff48ec328 error 14 in syz-executor925865502[400000+1000]
syz-executor925[29904]: segfault at 0 ip (null) sp 00007fdff48ec328 error 14 in syz-executor925865502[400000+1000]
syz-executor925[30242]: segfault at 0 ip (null) sp 00007fdff48ec328 error 14 in syz-executor925865502[400000+1000]
syz-executor925[30352]: segfault at 0 ip (null) sp 00007fdff48ec328 error 14 in syz-executor925865502[400000+1000]
syz-executor925[30748]: segfault at 0 ip (null) sp 00007fdff48ec328 error 14 in syz-executor925865502[400000+1000]
syz-executor925[30973]: segfault at 0 ip (null) sp 00007fdff48ec328 error 14 in syz-executor925865502[400000+1000]
syz-executor925[31461]: segfault at 0 ip (null) sp 00007fdff48ec328 error 14 in syz-executor925865502[400000+1000]