Hello all,
When enabling BT discovery I have this WARNING.
Linux 6.0.16, ARM, i.MX6ULL, with a Marvell BT device.
This looks like a regression on Linux 6.0, however I had no way to try
to bisect this yet. Any suggestion?
[ 493.824758] ======================================================
[ 493.831012] WARNING: possible circular locking dependency detected
[ 493.837261] 6.0.16-6.1.0-devel+git.29e1bc6a55de #1 Not tainted
[ 493.843171] ------------------------------------------------------
[ 493.849416] kworker/u3:0/39 is trying to acquire lock:
[ 493.854627] c2adcb18 (&hdev->req_lock){+.+.}-{3:3}, at: le_scan_disable_work+0x68/0x200
[ 493.862877]
[ 493.862877] but task is already holding lock:
[ 493.868773] e0abdf28 ((work_completion)(&(&hdev->le_scan_disable)->work)){+.+.}-{0:0}, at: process_one_work+0x1e4/0x6f4
[ 493.879775]
[ 493.879775] which lock already depends on the new lock.
[ 493.879775]
[ 493.888017]
[ 493.888017] the existing dependency chain (in reverse order) is:
[ 493.895564]
[ 493.895564] -> #1 ((work_completion)(&(&hdev->le_scan_disable)->work)){+.+.}-{0:0}:
[ 493.904868] __cancel_work_timer+0x198/0x224
[ 493.909762] hci_request_cancel_all+0x1c/0xb0
[ 493.914746] hci_dev_close_sync+0x38/0x5ac
[ 493.919456] hci_dev_do_close+0x30/0x64
[ 493.923904] process_one_work+0x280/0x6f4
[ 493.928526] worker_thread+0x40/0x4f8
[ 493.932801] kthread+0xe0/0x100
[ 493.936550] ret_from_fork+0x14/0x2c
[ 493.940738]
[ 493.940738] -> #0 (&hdev->req_lock){+.+.}-{3:3}:
[ 493.947001] lock_acquire+0xf4/0x364
[ 493.951190] __mutex_lock+0x80/0x8a0
[ 493.955378] mutex_lock_nested+0x1c/0x24
[ 493.959912] le_scan_disable_work+0x68/0x200
[ 493.964800] process_one_work+0x280/0x6f4
[ 493.969424] worker_thread+0x40/0x4f8
[ 493.973698] kthread+0xe0/0x100
[ 493.977447] ret_from_fork+0x14/0x2c
[ 493.981632]
[ 493.981632] other info that might help us debug this:
[ 493.981632]
[ 493.989702] Possible unsafe locking scenario:
[ 493.989702]
[ 493.995682] CPU0 CPU1
[ 494.000270] ---- ----
[ 494.004857] lock((work_completion)(&(&hdev->le_scan_disable)->work));
[ 494.011583] lock(&hdev->req_lock);
[ 494.017783] lock((work_completion)(&(&hdev->le_scan_disable)->work));
[ 494.027025] lock(&hdev->req_lock);
[ 494.030704]
[ 494.030704] *** DEADLOCK ***
[ 494.030704]
[ 494.036685] 2 locks held by kworker/u3:0/39:
[ 494.041026] #0: c2bb6ca8 ((wq_completion)hci0){+.+.}-{0:0}, at: process_one_work+0x1e4/0x6f4
[ 494.049786] #1: e0abdf28 ((work_completion)(&(&hdev->le_scan_disable)->work)){+.+.}-{0:0}, at: process_one_work+0x1e4/0x6f4
[ 494.061236]
[ 494.061236] stack backtrace:
[ 494.065659] CPU: 0 PID: 39 Comm: kworker/u3:0 Not tainted 6.0.16-6.1.0-devel+git.29e1bc6a55de #1
[ 494.074540] Hardware name: Freescale i.MX6 Ultralite (Device Tree)
[ 494.080797] Workqueue: hci0 le_scan_disable_work
[ 494.085547] unwind_backtrace from show_stack+0x10/0x14
[ 494.090902] show_stack from dump_stack_lvl+0x58/0x70
[ 494.096089] dump_stack_lvl from check_noncircular+0xe8/0x158
[ 494.101985] check_noncircular from __lock_acquire+0x1510/0x288c
[ 494.108120] __lock_acquire from lock_acquire+0xf4/0x364
[ 494.113541] lock_acquire from __mutex_lock+0x80/0x8a0
[ 494.118789] __mutex_lock from mutex_lock_nested+0x1c/0x24
[ 494.124384] mutex_lock_nested from le_scan_disable_work+0x68/0x200
[ 494.130770] le_scan_disable_work from process_one_work+0x280/0x6f4
[ 494.137160] process_one_work from worker_thread+0x40/0x4f8
[ 494.142852] worker_thread from kthread+0xe0/0x100
[ 494.147756] kthread from ret_from_fork+0x14/0x2c
[ 494.152565] Exception stack(0xe0abdfb0 to 0xe0abdff8)
[ 494.157708] dfa0: 00000000 00000000 00000000 00000000
[ 494.165982] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 494.174248] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
Francesco
On Tue, Jan 03, 2023 at 09:31:24PM +0100, Francesco Dolcini wrote:
> Hello all,
> When enabling BT discovery I have this WARNING.
>
> Linux 6.0.16, ARM, i.MX6ULL, with a Marvell BT device.
Linux 6.1.4 is fine.
I'm not planning to bisect it since I can just move to the new kernel.
> This looks like a regression on Linux 6.0, however I had no way to try
> to bisect this yet. Any suggestion?
>
> [ 493.824758] ======================================================
> [ 493.831012] WARNING: possible circular locking dependency detected
> [ 493.837261] 6.0.16-6.1.0-devel+git.29e1bc6a55de #1 Not tainted
Francesco