linux-kernel - Re: [PATCH v2 2/2] tty: Fix race against tty_open() in tty_register_device

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Message-ID: <202506031638.a5c78088-lkp@intel.com>
Date: Tue, 3 Jun 2025 16:49:31 +0800
From: kernel test robot <oliver.sang@...el.com>
To: Max Staudt <max@...as.org>
CC: <oe-lkp@...ts.linux.dev>, <lkp@...el.com>, <linux-kernel@...r.kernel.org>,
	<linux-serial@...r.kernel.org>, Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>, Johan Hovold
	<johan@...nel.org>, Max Staudt <max@...as.org>, <stable@...r.kernel.org>,
	<oliver.sang@...el.com>
Subject: Re: [PATCH v2 2/2] tty: Fix race against tty_open() in
 tty_register_device_attr()



Hello,

kernel test robot noticed "WARNING:possible_circular_locking_dependency_detected" on:

commit: c3184e841ee2a1585b89e4bbd90cacb41063871f ("[PATCH v2 2/2] tty: Fix race against tty_open() in tty_register_device_attr()")
url: https://github.com/intel-lab-lkp/linux/commits/Max-Staudt/tty-Fix-race-against-tty_open-in-tty_register_device_attr/20250528-213024
base: https://git.kernel.org/cgit/linux/kernel/git/gregkh/tty.git tty-testing
patch link: https://lore.kernel.org/all/20250528132816.11433-2-max@enpas.org/
patch subject: [PATCH v2 2/2] tty: Fix race against tty_open() in tty_register_device_attr()

in testcase: boot

config: x86_64-randconfig-001-20250530
compiler: gcc-12
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G

(please refer to attached dmesg/kmsg for entire log/backtrace)


+-------------------------------------------------------------------------------------------------------------------------------------------------------+------------+------------+
|                                                                                                                                                       | 44db64e370 | c3184e841e |
+-------------------------------------------------------------------------------------------------------------------------------------------------------+------------+------------+
| WARNING:possible_circular_locking_dependency_detected                                                                                                 | 0          | 6          |
| WARNING:possible_circular_locking_dependency_detected_swapper_is_trying_to_acquire_lock:at:tty_port_open_but_task_is_already_holding_lock:at:tty_lock | 0          | 6          |
+-------------------------------------------------------------------------------------------------------------------------------------------------------+------------+------------+


If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@...el.com>
| Closes: https://lore.kernel.org/oe-lkp/202506031638.a5c78088-lkp@intel.com


[   22.678060][    T1] WARNING: possible circular locking dependency detected
[   22.678860][    T1] 6.15.0-rc4-00108-gc3184e841ee2 #1 Tainted: G                T
[   22.679596][    T1] ------------------------------------------------------
[   22.680280][    T1] swapper/1 is trying to acquire lock:
[ 22.680750][ T1] ffff888101cf02d0 (&port->mutex){+.+.}-{4:4}, at: tty_port_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/tty_port.c:761) 
[   22.681597][    T1]
[   22.681597][    T1] but task is already holding lock:
[ 22.682232][ T1] ffff8881084f91e0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_lock (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/tty_mutex.c:19) 
[   22.683067][    T1]
[   22.683067][    T1] which lock already depends on the new lock.
[   22.683067][    T1]
[   22.683981][    T1]
[   22.683981][    T1] the existing dependency chain (in reverse order) is:
[   22.684732][    T1]
[   22.684732][    T1] -> #2 (&tty->legacy_mutex){+.+.}-{4:4}:
[ 22.685465][ T1] validate_chain (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:3286 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:3909) 
[ 22.685990][ T1] __lock_acquire (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:5235) 
[ 22.688240][ T1] lock_acquire (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:472 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:5868 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:5823) 
[ 22.688677][ T1] __mutex_lock (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/mutex.c:603 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/mutex.c:746) 
[ 22.689128][ T1] mutex_lock_nested (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/mutex.c:799) 
[ 22.689636][ T1] tty_lock (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/tty_mutex.c:19) 
[ 22.690065][ T1] tty_init_dev (kbuild/obj/consumer/x86_64-randconfig-001-20250530/include/linux/module.h:730) 
[ 22.690553][ T1] tty_init_dev (kbuild/obj/consumer/x86_64-randconfig-001-20250530/include/linux/module.h:730) 
[ 22.691065][ T1] tty_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/tty_io.c:2073 kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/tty_io.c:2120) 
[ 22.691582][ T1] chrdev_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/char_dev.c:414) 
[ 22.692010][ T1] do_dentry_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/open.c:956) 
[ 22.692506][ T1] vfs_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/open.c:1087) 
[ 22.692910][ T1] do_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/namei.c:3881) 
[ 22.693344][ T1] path_openat (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/namei.c:4039) 
[ 22.693796][ T1] do_filp_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/namei.c:4067) 
[ 22.694218][ T1] file_open_name (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/open.c:1374) 
[ 22.694669][ T1] filp_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/open.c:1394) 
[ 22.695063][ T1] console_on_rootfs (kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1528) 
[ 22.695624][ T1] kernel_init_freeable (kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1578) 
[ 22.696135][ T1] kernel_init (kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1459) 
[ 22.696554][ T1] ret_from_fork (kbuild/obj/consumer/x86_64-randconfig-001-20250530/arch/x86/kernel/process.c:159) 
[ 22.697060][ T1] ret_from_fork_asm (kbuild/obj/consumer/x86_64-randconfig-001-20250530/arch/x86/entry/entry_64.S:258) 
[   22.697516][    T1]
[   22.697516][    T1] -> #1 (tty_mutex){+.+.}-{4:4}:
[ 22.698166][ T1] validate_chain (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:3286 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:3909) 
[ 22.698652][ T1] __lock_acquire (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:5235) 
[ 22.699158][ T1] lock_acquire (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:472 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:5868 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:5823) 
[ 22.699577][ T1] __mutex_lock (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/mutex.c:603 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/mutex.c:746) 
[ 22.700113][ T1] mutex_lock_nested (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/mutex.c:799) 
[ 22.700564][ T1] tty_register_device_attr (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/tty_io.c:3250) 
[ 22.701135][ T1] tty_port_register_device_attr_serdev (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/tty_port.c:199) 
[ 22.701722][ T1] serial_core_add_one_port (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/serial/serial_core.c:3184) 
[ 22.702255][ T1] serial_core_register_port (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/serial/serial_core.c:3388) 
[ 22.702868][ T1] serial_ctrl_register_port (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/serial/serial_ctrl.c:42) 
[ 22.703443][ T1] uart_add_one_port (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/serial/serial_port.c:144) 
[ 22.703888][ T1] serial8250_register_8250_port (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/serial/8250/8250_core.c:822) 
[ 22.704473][ T1] serial_pnp_probe (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/serial/8250/8250_pnp.c:480) 
[ 22.704935][ T1] pnp_device_probe (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/pnp/driver.c:113) 
[ 22.705438][ T1] really_probe (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/base/dd.c:579 kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/base/dd.c:657) 
[ 22.705882][ T1] __driver_probe_device (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/base/dd.c:799) 
[ 22.706388][ T1] driver_probe_device (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/base/dd.c:829) 
[ 22.706886][ T1] __driver_attach (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/base/dd.c:1216 kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/base/dd.c:1155) 
[ 22.707345][ T1] bus_for_each_dev (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/base/bus.c:369) 
[ 22.707854][ T1] driver_attach (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/base/dd.c:1234) 
[ 22.708343][ T1] bus_add_driver (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/base/bus.c:678) 
[ 22.708788][ T1] driver_register (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/base/driver.c:249) 
[ 22.709313][ T1] pnp_register_driver (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/pnp/driver.c:281) 
[ 22.709779][ T1] serial8250_pnp_init (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/serial/8250/8250_pnp.c:531) 
[ 22.710314][ T1] serial8250_init (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/serial/8250/8250_platform.c:315) 
[ 22.710850][ T1] do_one_initcall (kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1257) 
[ 22.711331][ T1] do_initcalls (kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1318 kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1335) 
[ 22.711819][ T1] kernel_init_freeable (kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1569) 
[ 22.712320][ T1] kernel_init (kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1459) 
[ 22.712739][ T1] ret_from_fork (kbuild/obj/consumer/x86_64-randconfig-001-20250530/arch/x86/kernel/process.c:159) 
[ 22.713196][ T1] ret_from_fork_asm (kbuild/obj/consumer/x86_64-randconfig-001-20250530/arch/x86/entry/entry_64.S:258) 
[   22.713650][    T1]
[   22.713650][    T1] -> #0 (&port->mutex){+.+.}-{4:4}:
[ 22.714356][ T1] check_noncircular (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:2215) 
[ 22.714826][ T1] check_prev_add (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:3167) 
[ 22.715274][ T1] validate_chain (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:3286 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:3909) 
[ 22.715793][ T1] __lock_acquire (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:5235) 
[ 22.716237][ T1] lock_acquire (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:472 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:5868 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/lockdep.c:5823) 
[ 22.716741][ T1] __mutex_lock (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/mutex.c:603 kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/mutex.c:746) 
[ 22.717172][ T1] mutex_lock_nested (kbuild/obj/consumer/x86_64-randconfig-001-20250530/kernel/locking/mutex.c:799) 
[ 22.717631][ T1] tty_port_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/tty_port.c:761) 
[ 22.718106][ T1] uart_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/serial/serial_core.c:1974) 
[ 22.718642][ T1] tty_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/drivers/tty/tty_io.c:2140) 
[ 22.719094][ T1] chrdev_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/char_dev.c:414) 
[ 22.719514][ T1] do_dentry_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/open.c:956) 
[ 22.719966][ T1] vfs_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/open.c:1087) 
[ 22.720411][ T1] do_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/namei.c:3881) 
[ 22.720873][ T1] path_openat (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/namei.c:4039) 
[ 22.721298][ T1] do_filp_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/namei.c:4067) 
[ 22.721848][ T1] file_open_name (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/open.c:1374) 
[ 22.722280][ T1] filp_open (kbuild/obj/consumer/x86_64-randconfig-001-20250530/fs/open.c:1394) 
[ 22.722739][ T1] console_on_rootfs (kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1528) 
[ 22.723194][ T1] kernel_init_freeable (kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1578) 
[ 22.723695][ T1] kernel_init (kbuild/obj/consumer/x86_64-randconfig-001-20250530/init/main.c:1459) 
[ 22.724200][ T1] ret_from_fork (kbuild/obj/consumer/x86_64-randconfig-001-20250530/arch/x86/kernel/process.c:159) 
[ 22.724709][ T1] ret_from_fork_asm (kbuild/obj/consumer/x86_64-randconfig-001-20250530/arch/x86/entry/entry_64.S:258) 
[   22.725164][    T1]
[   22.725164][    T1] other info that might help us debug this:
[   22.725164][    T1]
[   22.726026][    T1] Chain exists of:
[   22.726026][    T1]   &port->mutex --> tty_mutex --> &tty->legacy_mutex
[   22.726026][    T1]


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20250603/202506031638.a5c78088-lkp@intel.com



-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki