linux-kernel - Re: [syzbot] [bluetooth?] possible deadlock in touch_wq_lockdep

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Message-ID: <000000000000fb901b061c4e0282@google.com>
Date: Tue, 02 Jul 2024 18:47:23 -0700
From: syzbot <syzbot+91dbdfecdd3287734d8e@...kaller.appspotmail.com>
To: johan.hedberg@...il.com, linux-bluetooth@...r.kernel.org, 
	linux-kernel@...r.kernel.org, luiz.dentz@...il.com, marcel@...tmann.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bluetooth?] possible deadlock in touch_wq_lockdep_map

syzbot has found a reproducer for the following issue on:

HEAD commit:    734610514cb0 Merge tag 'erofs-for-6.10-rc7-fixes' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=151ea512980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=de2d4dc103148cd6
dashboard link: https://syzkaller.appspot.com/bug?extid=91dbdfecdd3287734d8e
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1424d281980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-73461051.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d390d5c7156f/vmlinux-73461051.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b56ef48ffa7e/bzImage-73461051.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+91dbdfecdd3287734d8e@...kaller.appspotmail.com

Bluetooth: hci0: hardware error 0x20
Bluetooth: hci0: Opcode 0x0c03 failed: -110
============================================
WARNING: possible recursive locking detected
6.10.0-rc6-syzkaller-00055-g734610514cb0 #0 Not tainted
--------------------------------------------
kworker/u33:1/4633 is trying to acquire lock:
ffff88802b9cc148 ((wq_completion)hci0){+.+.}-{0:0}, at: touch_wq_lockdep_map+0x6e/0x120 kernel/workqueue.c:3895

but task is already holding lock:
ffff88802b9cc148 ((wq_completion)hci0){+.+.}-{0:0}, at: process_one_work+0x1277/0x1b40 kernel/workqueue.c:3223

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock((wq_completion)hci0);
  lock((wq_completion)hci0);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by kworker/u33:1/4633:
 #0: ffff88802b9cc148 ((wq_completion)hci0){+.+.}-{0:0}, at: process_one_work+0x1277/0x1b40 kernel/workqueue.c:3223
 #1: ffffc90025177d80 ((work_completion)(&hdev->error_reset)){+.+.}-{0:0}, at: process_one_work+0x921/0x1b40 kernel/workqueue.c:3224

stack backtrace:
CPU: 2 PID: 4633 Comm: kworker/u33:1 Not tainted 6.10.0-rc6-syzkaller-00055-g734610514cb0 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: hci0 hci_error_reset
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain kernel/locking/lockdep.c:3856 [inline]
 __lock_acquire+0x20e6/0x3b30 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
 touch_wq_lockdep_map+0x78/0x120 kernel/workqueue.c:3895
 __flush_workqueue+0x129/0x1200 kernel/workqueue.c:3937
 drain_workqueue+0x18f/0x3d0 kernel/workqueue.c:4101
 destroy_workqueue+0xc2/0xaa0 kernel/workqueue.c:5817
 hci_release_dev+0x14e/0x660 net/bluetooth/hci_core.c:2795
 bt_host_release+0x6a/0xb0 net/bluetooth/hci_sysfs.c:94
 device_release+0xa1/0x240 drivers/base/core.c:2581
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1fa/0x5b0 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3787
 process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3248
 process_scheduled_works kernel/workqueue.c:3329 [inline]
 worker_thread+0x6c8/0xf30 kernel/workqueue.c:3409
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.