WARNING: refcount bug in io_worker

WARNING: refcount bug in io_worker_exit
Status: upstream: reported on 2020/09/14 09:34
Reported-by: syzbot+c4934d8fed67bdb3b763@syzkaller.appspotmail.com
First crash: 16d, last: 9d01h

Sample crash report:

WARNING: CPU: 1 PID: 8876 at lib/refcount.c:28 refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 8876 Comm: io_wqe_worker-1 Not tainted 5.9.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d6/0x29e lib/dump_stack.c:118
 panic+0x2c0/0x800 kernel/panic.c:231
 __warn+0x227/0x250 kernel/panic.c:600
 report_bug+0x1b1/0x2e0 lib/bug.c:198
 handle_bug+0x42/0x80 arch/x86/kernel/traps.c:234
 exc_invalid_op+0x16/0x40 arch/x86/kernel/traps.c:254
 asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536
RIP: 0010:refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28
Code: c7 9a 9e 15 89 31 c0 e8 e3 1d a6 fd 0f 0b eb 85 e8 4a 7f d4 fd c6 05 76 73 ea 05 01 48 c7 c7 c6 9e 15 89 31 c0 e8 c5 1d a6 fd <0f> 0b e9 64 ff ff ff e8 29 7f d4 fd c6 05 56 73 ea 05 01 48 c7 c7
RSP: 0018:ffffc900073bfdb8 EFLAGS: 00010246
RAX: 84a3820803048f00 RBX: 0000000000000003 RCX: ffff888094092200
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000003 R08: ffffffff815e3810 R09: ffffed1015d262c0
R10: ffffed1015d262c0 R11: 0000000000000000 R12: ffff888095c3d0b8
R13: dffffc0000000000 R14: ffff88809ff16f00 R15: ffff8880a9550230
 refcount_sub_and_test include/linux/refcount.h:274 [inline]
 refcount_dec_and_test include/linux/refcount.h:294 [inline]
 io_worker_exit+0x63f/0x750 fs/io-wq.c:236
 io_wqe_worker+0x799/0x810 fs/io-wq.c:596
 kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (4):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci-upstream-kasan-gce-smack-root	2020/09/20 04:04	upstream	eb5f95f1	53ce8104	.config	log	report	info	axboe@kernel.dk, io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/09/14 09:04	upstream	e4c26faa	2d3cdd63	.config	log	report		axboe@kernel.dk, io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/09/13 23:12	upstream	e4c26faa	2d3cdd63	.config	log	report		axboe@kernel.dk, io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci-upstream-kasan-gce-smack-root	2020/09/12 23:46	upstream	729e3d09	ce441f06	.config	log	report		axboe@kernel.dk, io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk