[syzbot] WARNING: refcount bug in default_device_exit_batch

[syzbot] WARNING: refcount bug in default_device_exit_batch

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    08fcdfa6e3ae nfc: port100: lower verbosity of cancelled UR..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=10325fb6b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a5d447cdc3ae81d9
dashboard link: https://syzkaller.appspot.com/bug?extid=5971b9b300c59af94177
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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+5971b9b300c59af94177@syzkaller.appspotmail.com

bond0 (unregistering): (slave bond_slave_1): Releasing backup interface
bond0 (unregistering): (slave bond_slave_0): Releasing backup interface
bond0 (unregistering): Released all slaves
------------[ cut here ]------------
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 0 PID: 15049 at lib/refcount.c:31 refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31
Modules linked in:
CPU: 0 PID: 15049 Comm: kworker/u4:8 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
RIP: 0010:refcount_warn_saturate+0xbf/0x1e0 lib/refcount.c:31
Code: 1d a9 13 82 09 31 ff 89 de e8 ad ae 9e fd 84 db 75 e0 e8 64 a8 9e fd 48 c7 c7 20 2a e4 89 c6 05 89 13 82 09 01 e8 c1 55 1b 05 <0f> 0b eb c4 e8 48 a8 9e fd 0f b6 1d 78 13 82 09 31 ff 89 de e8 78
RSP: 0018:ffffc900045dfa10 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888078fcba00 RSI: ffffffff815ef908 RDI: fffff520008bbf34
RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815e96ee R11: 0000000000000000 R12: 0000000000000001
R13: ffffc900045dfb68 R14: ffff8880784105b0 R15: ffff88802a8bc5a0
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcf4f55b000 CR3: 000000001b5cc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __refcount_dec include/linux/refcount.h:344 [inline]
 refcount_dec include/linux/refcount.h:359 [inline]
 dev_put include/linux/netdevice.h:4166 [inline]
 unregister_netdevice_many+0x12c9/0x1790 net/core/dev.c:11111
 default_device_exit_batch+0x2fa/0x3c0 net/core/dev.c:11604
 ops_exit_list+0x10d/0x160 net/core/net_namespace.c:171
 cleanup_net+0x4ea/0xb00 net/core/net_namespace.c:593
 process_one_work+0x9b2/0x1690 kernel/workqueue.c:2297
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2444
 kthread+0x405/0x4f0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>


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