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Date: Thu, 3 Aug 2017 09:43:26 +0000
From: "Coelho, Luciano" <luciano.coelho@...el.com>
To: "jikos@...nel.org" <jikos@...nel.org>,
"Zhang, Rui" <rui.zhang@...el.com>,
"kvalo@...eaurora.org" <kvalo@...eaurora.org>,
"edubezval@...il.com" <edubezval@...il.com>,
"Sharon, Sara" <sara.sharon@...el.com>,
"Berg, Johannes" <johannes.berg@...el.com>,
"Grumbach, Emmanuel" <emmanuel.grumbach@...el.com>
CC: linuxwifi <linuxwifi@...el.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
"Weinehall, David" <david.weinehall@...el.com>
Subject: Re: [linuxwifi] x86/thermal: AB-BA dependency between mvm->mutex
and tz->lock
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:
> >
> > CPU0 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!
--
Luca.
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