WARNING: refcount bug in p9_tag_lookup

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ff511c1c68a5 Add linux-next specific files for 20220408
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=178ae9a7700000
kernel config: https://syzkaller.appspot.com/x/.config?x=d0168787d544f48e
dashboard link: https://syzkaller.appspot.com/bug?extid=0a99744ed856bf4580fa
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
CC: [asma...@codewreck.org da...@davemloft.net eri...@gmail.com ku...@kernel.org linux-...@vger.kernel.org linu...@crudebyte.com lu...@ionkov.net net...@vger.kernel.org pab...@redhat.com v9fs-de...@lists.sourceforge.net]

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+0a9974...@syzkaller.appspotmail.com

------------[ cut here ]------------
refcount_t: saturated; leaking memory.
WARNING: CPU: 1 PID: 5697 at lib/refcount.c:19 refcount_warn_saturate+0xf4/0x1e0 lib/refcount.c:19
Modules linked in:
CPU: 1 PID: 5697 Comm: kworker/1:19 Not tainted 5.18.0-rc1-next-20220408-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events p9_read_work
RIP: 0010:refcount_warn_saturate+0xf4/0x1e0 lib/refcount.c:19
Code: 1d 41 fb b2 09 31 ff 89 de e8 a8 31 8a fd 84 db 75 ab e8 bf 2d 8a fd 48 c7 c7 e0 a4 26 8a c6 05 21 fb b2 09 01 e8 41 e7 2e 05 <0f> 0b eb 8f e8 a3 2d 8a fd 0f b6 1d 0b fb b2 09 31 ff 89 de e8 73
RSP: 0018:ffffc9000cd87b78 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88801dae1d40 RSI: ffffffff8160a278 RDI: fffff520019b0f61
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff81604c4e R11: 0000000000000000 R12: ffff88823bd66008
R13: dffffc0000000000 R14: 0000000000000000 R15: 00000000a9a8abaa
FS: 0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000200fc000 CR3: 00000000452c5000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__refcount_add_not_zero include/linux/refcount.h:163 [inline]
__refcount_inc_not_zero include/linux/refcount.h:227 [inline]
refcount_inc_not_zero include/linux/refcount.h:245 [inline]
kref_get_unless_zero include/linux/kref.h:111 [inline]
p9_req_try_get include/net/9p/client.h:235 [inline]
p9_tag_lookup+0x2b3/0x570 net/9p/client.c:341
p9_read_work+0x759/0x1020 net/9p/trans_fd.c:334
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
</TASK>


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.