[syzbot] WARNING in dec_ucount

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    3dbdb38e Merge branch 'for-5.14' of git://git.kernel.org/p..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1023db52300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a1fcf15a09815757
dashboard link: https://syzkaller.appspot.com/bug?extid=493df5f976efd79b9b66

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+493df5f976efd79b9b66@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
WARNING: CPU: 1 PID: 22176 at kernel/ucount.c:246 dec_ucount+0x10d/0x130 kernel/ucount.c:246
Modules linked in:
CPU: 1 PID: 22176 Comm: kworker/u4:3 Tainted: G        W         5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
RIP: 0010:dec_ucount+0x10d/0x130 kernel/ucount.c:246
Code: 4d 85 e4 0f 85 52 ff ff ff e8 0f f7 26 00 48 8b 3c 24 48 83 c4 08 5b 5d 41 5c 41 5d 41 5e 41 5f e9 28 f5 ff ff e8 f3 f6 26 00 <0f> 0b eb 99 48 89 ef e8 97 b4 6c 00 e9 48 ff ff ff e8 8d b4 6c 00
RSP: 0018:ffffc90023a1fc38 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff8881626354c0 RSI: ffffffff814e933d RDI: 0000000000000003
RBP: ffff8880192d3240 R08: 0000000000000000 R09: ffff8880192d3247
R10: ffffffff814e92ad R11: 0000000000000000 R12: ffff8880192d3200
R13: dffffc0000000000 R14: 0000000000000040 R15: ffffffffffffffff
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000014a401000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 dec_net_namespaces net/core/net_namespace.c:394 [inline]
 cleanup_net+0x6f3/0xb10 net/core/net_namespace.c:611
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295


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