Subject: [syzbot] WARNING: refcount bug in __linkwatch_run_queue

From: syzbot <[email-masked]>
Date: Tue, 16 Nov 2021 01:23:19 -0800

Hello,

syzbot found the following issue on:

HEAD commit:    fa55b7dcdc43 Linux 5.16-rc1
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=109339e1b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6c3ab72998e7f1a4
dashboard link: https://syzkaller.appspot.com/bug?extid=6f8ddb9f2ff4adf065cb
compiler:       Debian clang version 11.0.1-2, 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: [email-masked]

------------[ cut here ]------------
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 1 PID: 26140 at lib/refcount.c:31 refcount_warn_saturate+0x17c/0x1a0 lib/refcount.c:31
Modules linked in:
CPU: 1 PID: 26140 Comm: kworker/1:26 Not tainted 5.16.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events linkwatch_event
RIP: 0010:refcount_warn_saturate+0x17c/0x1a0 lib/refcount.c:31
Code: f4 8a 31 c0 e8 f5 45 38 fd 0f 0b e9 64 ff ff ff e8 49 6a 6e fd c6 05 06 40 f5 09 01 48 c7 c7 80 fe f4 8a 31 c0 e8 d4 45 38 fd <0f> 0b e9 43 ff ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c a2 fe ff
RSP: 0018:ffffc90003537b68 EFLAGS: 00010246
RAX: 26aa35cdf4075e00 RBX: 0000000000000004 RCX: ffff88803baaba00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000004 R08: ffffffff8169fb82 R09: ffffed10173667b1
R10: ffffed10173667b1 R11: 0000000000000000 R12: ffff88807ccac000
R13: 1ffff1100f9958b7 R14: 1ffff1100f9958b8 R15: ffff88807ccac5b8
FS:  0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f217b0e6740 CR3: 0000000019e96000 CR4: 00000000003526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 000000000000ff46
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __linkwatch_run_queue+0x4f5/0x800 net/core/link_watch.c:213
 linkwatch_event+0x48/0x50 net/core/link_watch.c:252
 process_one_work+0x853/0x1140 kernel/workqueue.c:2298
 worker_thread+0xac1/0x1320 kernel/workqueue.c:2445
 kthread+0x468/0x490 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30
 </TASK>

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