Re: [linuxwifi] x86/thermal: AB-BA dependency between mvm->mutex and tz->lock

From: Kalle Valo
Date: Thu Aug 03 2017 - 06:02:36 EST

"Coelho, Luciano" <luciano.coelho@xxxxxxxxx> writes:

> On Thu, 2017-08-03 at 11:10 +0200, Jiri Kosina wrote:
>> On Mon, 31 Jul 2017, Jiri Kosina wrote:
>>
>> > Hi,
>> >
>> > booting current Linus' tree, I'm seeing lockdep splat (see the end of this
>> > mail).
>> >
>> > Apparently, there is AB-BA between tz->lock and mvm->mutex through the CPU
>> > hotplug lock.
>> >
>> > The obivous depency is: thermal_zone_get_temp() acquires tz->lock, and
>> > then calls iwl_mvm_tzone_get_temp() (through tz->ops->get_temp()
>> > callback), which acquires mvm->mutex
>> >
>> > The less obvious dependency is primarily caused by iwl_op_mode_mvm_start()
>> > allocating workqueue (#2 stacktrace) while holding mvm->mutex (which is
>> > broken, because that mutex is being taken also from CPU hotplug callback
>> > path, hence the AB-BA).
>>
>> As the "central" part of the dependency is being added by iwlwifi driver
>> (_iwl_pcie_rx_init() allocating workqueue while holding
>> trans_pcie->mutex), I'm adding iwlwifi folks as well to CC.
>>
>> >
>> > ======================================================
>> > WARNING: possible circular locking dependency detected
>> > 4.13.0-rc2-00110-g0b5477d #347 Not tainted
>> > ------------------------------------------------------
>> > modprobe/881 is trying to acquire lock:
>> > (&mvm->mutex){+.+.+.}, at: [<ffffffffc0c504d2>] iwl_mvm_tzone_get_temp+0x32/0x80 [iwlmvm]
>> >
>> > but task is already holding lock:
>> > (&tz->lock){+.+.+.}, at: [<ffffffff926a9351>] thermal_zone_get_temp+0x41/0x70
>> >
>> > which lock already depends on the new lock.
>> >
>> >
>> > the existing dependency chain (in reverse order) is:
>> >
>> > -> #5 (&tz->lock){+.+.+.}:
>> > lock_acquire+0xbd/0x220
>> > __mutex_lock+0x6e/0x900
>> > mutex_lock_nested+0x1b/0x20
>> > thermal_zone_get_temp+0x41/0x70
>> > thermal_zone_device_update+0x3c/0x280
>> > thermal_zone_device_register+0x3b8/0x610
>> > pkg_thermal_cpu_online+0x20b/0x284 [x86_pkg_temp_thermal]
>> > cpuhp_invoke_callback+0xac/0x900
>> > cpuhp_thread_fun+0x79/0x160
>> > smpboot_thread_fn+0x156/0x220
>> > kthread+0x114/0x150
>> > ret_from_fork+0x2a/0x40
>> >
>> > -> #4 (cpuhp_state){+.+.+.}:
>> > lock_acquire+0xbd/0x220
>> > cpuhp_issue_call+0xea/0x170
>> > __cpuhp_setup_state_cpuslocked+0x12a/0x190
>> > __cpuhp_setup_state+0x46/0xc0
>> > page_writeback_init+0x43/0x67
>> > pagecache_init+0x39/0x3c
>> > start_kernel+0x45a/0x4ae
>> > x86_64_start_reservations+0x24/0x26
>> > x86_64_start_kernel+0x13d/0x14c
>> > verify_cpu+0x0/0xf1
>> >
>> > -> #3 (cpuhp_state_mutex){+.+.+.}:
>> > lock_acquire+0xbd/0x220
>> > __mutex_lock+0x6e/0x900
>> > mutex_lock_nested+0x1b/0x20
>> > __cpuhp_setup_state_cpuslocked+0x4f/0x190
>> > __cpuhp_setup_state+0x46/0xc0
>> > page_alloc_init+0x28/0x30
>> > start_kernel+0x186/0x4ae
>> > x86_64_start_reservations+0x24/0x26
>> > x86_64_start_kernel+0x13d/0x14c
>> > verify_cpu+0x0/0xf1
>> >
>> > -> #2 (cpu_hotplug_lock.rw_sem){++++++}:
>> > lock_acquire+0xbd/0x220
>> > cpus_read_lock+0x46/0x90
>> > apply_workqueue_attrs+0x17/0x50
>> > __alloc_workqueue_key+0x195/0x4d0
>> > _iwl_pcie_rx_init+0x384/0x390 [iwlwifi]
>> > iwl_pcie_rx_init+0x1e/0x380 [iwlwifi]
>> > iwl_trans_pcie_start_fw+0x295/0x6f0 [iwlwifi]
>> > iwl_mvm_load_ucode_wait_alive+0xe7/0x390 [iwlmvm]
>> > iwl_run_init_mvm_ucode+0x84/0x320 [iwlmvm]
>> > iwl_op_mode_mvm_start+0x964/0xd30 [iwlmvm]
>> > _iwl_op_mode_start.isra.9+0x47/0xa0 [iwlwifi]
>> > iwl_opmode_register+0xaa/0xd0 [iwlwifi]
>> > iwl_mvm_init+0x37/0x1000 [iwlmvm]
>> > do_one_initcall+0x51/0x1a9
>> > do_init_module+0x60/0x20e
>> > load_module+0x203f/0x2b50
>> > SYSC_finit_module+0x96/0xd0
>> > SyS_finit_module+0xe/0x10
>> > entry_SYSCALL_64_fastpath+0x23/0xc2
>> >
>> > -> #1 (&trans_pcie->mutex){+.+.+.}:
>> > lock_acquire+0xbd/0x220
>> > __mutex_lock+0x6e/0x900
>> > mutex_lock_nested+0x1b/0x20
>> > iwl_trans_pcie_start_fw+0x130/0x6f0 [iwlwifi]
>> > iwl_mvm_load_ucode_wait_alive+0xe7/0x390 [iwlmvm]
>> > iwl_run_init_mvm_ucode+0x84/0x320 [iwlmvm]
>> > iwl_op_mode_mvm_start+0x964/0xd30 [iwlmvm]
>> > _iwl_op_mode_start.isra.9+0x47/0xa0 [iwlwifi]
>> > iwl_opmode_register+0xaa/0xd0 [iwlwifi]
>> > iwl_mvm_init+0x37/0x1000 [iwlmvm]
>> > do_one_initcall+0x51/0x1a9
>> > do_init_module+0x60/0x20e
>> > load_module+0x203f/0x2b50
>> > SYSC_finit_module+0x96/0xd0
>> > SyS_finit_module+0xe/0x10
>> > entry_SYSCALL_64_fastpath+0x23/0xc2
>> >
>> > -> #0 (&mvm->mutex){+.+.+.}:
>> > __lock_acquire+0x13e1/0x1400
>> > lock_acquire+0xbd/0x220
>> > __mutex_lock+0x6e/0x900
>> > mutex_lock_nested+0x1b/0x20
>> > iwl_mvm_tzone_get_temp+0x32/0x80 [iwlmvm]
>> > thermal_zone_get_temp+0x51/0x70
>> > thermal_zone_device_update+0x3c/0x280
>> > thermal_zone_device_register+0x3b8/0x610
>> > iwl_mvm_thermal_initialize+0x1d1/0x3a0 [iwlmvm]
>> > iwl_op_mode_mvm_start+0xa1d/0xd30 [iwlmvm]
>> > _iwl_op_mode_start.isra.9+0x47/0xa0 [iwlwifi]
>> > iwl_opmode_register+0xaa/0xd0 [iwlwifi]
>> > iwl_mvm_init+0x37/0x1000 [iwlmvm]
>> > do_one_initcall+0x51/0x1a9
>> > do_init_module+0x60/0x20e
>> > load_module+0x203f/0x2b50
>> > SYSC_finit_module+0x96/0xd0
>> > SyS_finit_module+0xe/0x10
>> > entry_SYSCALL_64_fastpath+0x23/0xc2
>> >
>> > other info that might help us debug this:
>> >
>> > Chain exists of:
>> > &mvm->mutex --> cpuhp_state --> &tz->lock
>> >
>> > Possible unsafe locking scenario:
>> >
>> > Â CPU0 Â CPU1
>> > ---- ----
>> > lock(&tz->lock);
>> > lock(cpuhp_state);
>> > lock(&tz->lock);
>> > lock(&mvm->mutex);
>> >
>> > *** DEADLOCK ***
>> >
>> > 2 locks held by modprobe/881:
>> > #0: (&iwlwifi_opmode_table_mtx){+.+.+.}, at: [<ffffffffc0aa2df4>] iwl_opmode_register+0x24/0xd0 [iwlwifi]
>> > #1: (&tz->lock){+.+.+.}, at: [<ffffffff926a9351>] thermal_zone_get_temp+0x41/0x70
>> >
>> > stack backtrace:
>> > CPU: 3 PID: 881 Comm: modprobe Not tainted 4.13.0-rc2-00110-g0b5477d #347
>> > Hardware name: LENOVO 20K5S22R00/20K5S22R00, BIOS R0IET38W (1.16 ) 05/31/2017
>> > Call Trace:
>> > dump_stack+0x85/0xc9
>> > print_circular_bug+0x1f9/0x207
>> > __lock_acquire+0x13e1/0x1400
>> > lock_acquire+0xbd/0x220
>> > ? iwl_mvm_tzone_get_temp+0x32/0x80 [iwlmvm]
>> > ? iwl_mvm_tzone_get_temp+0x32/0x80 [iwlmvm]
>> > __mutex_lock+0x6e/0x900
>> > ? iwl_mvm_tzone_get_temp+0x32/0x80 [iwlmvm]
>> > ? thermal_zone_get_temp+0x41/0x70
>> > ? iwl_mvm_tzone_get_temp+0x32/0x80 [iwlmvm]
>> > ? thermal_zone_get_temp+0x41/0x70
>> > ? find_held_lock+0x39/0xb0
>> > mutex_lock_nested+0x1b/0x20
>> > iwl_mvm_tzone_get_temp+0x32/0x80 [iwlmvm]
>> > thermal_zone_get_temp+0x51/0x70
>> > thermal_zone_device_update+0x3c/0x280
>> > thermal_zone_device_register+0x3b8/0x610
>> > iwl_mvm_thermal_initialize+0x1d1/0x3a0 [iwlmvm]
>> > iwl_op_mode_mvm_start+0xa1d/0xd30 [iwlmvm]
>> > _iwl_op_mode_start.isra.9+0x47/0xa0 [iwlwifi]
>> > iwl_opmode_register+0xaa/0xd0 [iwlwifi]
>> > iwl_mvm_init+0x37/0x1000 [iwlmvm]
>> > ? 0xffffffffc0c87000
>> > do_one_initcall+0x51/0x1a9
>> > ? rcu_read_lock_sched_held+0x98/0xa0
>> > ? kmem_cache_alloc_trace+0x2a5/0x340
>> > do_init_module+0x60/0x20e
>> > load_module+0x203f/0x2b50
>> > ? __symbol_put+0x50/0x50
>> > SYSC_finit_module+0x96/0xd0
>> > SyS_finit_module+0xe/0x10
>> > entry_SYSCALL_64_fastpath+0x23/0xc2
>> > RIP: 0033:0x7f2ef067cc89
>> > RSP: 002b:00007ffea2ea3d78 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
>> > RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f2ef067cc89
>> > RDX: 0000000000000000 RSI: 000000000041af06 RDI: 0000000000000001
>> > RBP: 0000000000000005 R08: 0000000000000000 R09: 000000000096b230
>> > R10: 0000000000000001 R11: 0000000000000246 R12: 00007ffea2ea2d80
>> > R13: 00007ffea2ea2d60 R14: 0000000000000005 R15: 000000000096f3c0
>> > thermal thermal_zone3: failed to read out thermal zone (-5)
>
> CCing David Weinehall who also just reported this to me.
>
> We'll check this ASAP. Thanks for reporting!

Adding linux-wireless also to the loop.

--
Kalle Valo