Bob, Rafael, any comments about this? This seems to solve a real issue with Thunderbolt hotplug on Dell XPS laptops. I do not know ACPICA that well to tell if this is 100% correct fix but many reporters say it fixes the problem they are facing: https://bugzilla.kernel.org/show_bug.cgi?id=115121 On Tue, Mar 29, 2016 at 06:45:40PM -0400, Prarit Bhargava wrote: > The following hung task trace is seen when hotplugging > an ethernet dongle in a Thunderbolt port on Linux. > > INFO: task kworker/0:4:1468 blocked for more than 120 seconds. > Tainted: G W 4.6.0-rc1+ #1 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > kworker/0:4 D ffff8802a265ba38 13344 1468 2 0x00000000 > Workqueue: kacpid acpi_os_execute_deferred > ffff8802a265ba38 ffff8802a265ba00 ffffffff81130200 ffffffff81e0d580 > ffff88029e5eb340 ffff8802a265c000 ffff88029d69d000 ffff88029e5eb340 > ffffffff818c1b8d ffff8802b64e8758 ffff8802a265ba50 ffffffff818bdfcc > Call Trace: > [<ffffffff81130200>] ? test_callback+0x10/0x30 > [<ffffffff818c1b8d>] ? __down_timeout+0x5d/0xd0 > [<ffffffff818bdfcc>] schedule+0x3c/0x90 > [<ffffffff818c2d60>] schedule_timeout+0x210/0x360 > [<ffffffff8103fc89>] ? sched_clock+0x9/0x10 > [<ffffffff810ee51c>] ? local_clock+0x1c/0x20 > [<ffffffff81110c16>] ? mark_held_locks+0x76/0xa0 > [<ffffffff818c3cfc>] ? _raw_spin_unlock_irq+0x2c/0x40 > [<ffffffff818c1b8d>] ? __down_timeout+0x5d/0xd0 > [<ffffffff81110d35>] ? trace_hardirqs_on_caller+0xf5/0x1b0 > [<ffffffff818c1b8d>] ? __down_timeout+0x5d/0xd0 > [<ffffffff818c1bac>] __down_timeout+0x7c/0xd0 > [<ffffffff818c44b2>] ? _raw_spin_lock_irqsave+0x82/0x90 > [<ffffffff8110b87c>] down_timeout+0x4c/0x60 > [<ffffffff814e3a9c>] acpi_os_wait_semaphore+0xaa/0x16a > [<ffffffff81510f37>] acpi_ex_system_wait_mutex+0x81/0xfa > [<ffffffff814f8796>] acpi_ds_begin_method_execution+0x25a/0x373 > [<ffffffff814f8cea>] acpi_ds_call_control_method+0x107/0x2e0 > [<ffffffff8151ed60>] acpi_ps_parse_aml+0x177/0x495 > [<ffffffff8151fa46>] acpi_ps_execute_method+0x1f7/0x2b9 > [<ffffffff81516c9a>] acpi_ns_evaluate+0x2ee/0x435 > [<ffffffff814ff84a>] acpi_ev_asynch_execute_gpe_method+0xbd/0x159 > [<ffffffff814e2a69>] acpi_os_execute_deferred+0x17/0x23 > [<ffffffff810d1fc2>] process_one_work+0x242/0x700 > [<ffffffff810d1f3a>] ? process_one_work+0x1ba/0x700 > [<ffffffff810d24ce>] worker_thread+0x4e/0x490 > [<ffffffff810d2480>] ? process_one_work+0x700/0x700 > [<ffffffff810d2480>] ? process_one_work+0x700/0x700 > [<ffffffff810d98b1>] kthread+0x101/0x120 > [<ffffffff81110d35>] ? trace_hardirqs_on_caller+0xf5/0x1b0 > [<ffffffff818c4832>] ret_from_fork+0x22/0x50 > [<ffffffff810d97b0>] ? kthread_create_on_node+0x250/0x250 > 2 locks held by kworker/0:4/1468: > #0: ("kacpid"){.+.+.+}, at: [<ffffffff810d1f3a>] process_one_work+0x1ba/0x700 > #1: ((&dpc->work)){+.+.+.}, at: [<ffffffff810d1f3a>] process_one_work+0x1ba/0x700 > > The issue appears to be that the kworker thread attempts to acquire the > _E42 method's mutex twice when executing acpi_ps_execute_method() and > recursing through the entry method. > > The current code does take the possiblity of this recursion into account, > however, it is only for the case where the walk_state has been populated. > > This can be fixed by setting the thread id in the !walk_state case to > allow for recursion. > > Cc: Robert Moore <robert.moore@xxxxxxxxx> > Cc: Lv Zheng <lv.zheng@xxxxxxxxx> > Cc: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx> > Cc: Len Brown <lenb@xxxxxxxxxx> > Cc: linux-acpi@xxxxxxxxxxxxxxx > Cc: devel@xxxxxxxxxx > Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx> > --- > drivers/acpi/acpica/dsmethod.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/acpi/acpica/dsmethod.c b/drivers/acpi/acpica/dsmethod.c > index 1982310..93799db 100644 > --- a/drivers/acpi/acpica/dsmethod.c > +++ b/drivers/acpi/acpica/dsmethod.c > @@ -428,6 +428,9 @@ acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node, > obj_desc->method.mutex->mutex. > original_sync_level = > obj_desc->method.mutex->mutex.sync_level; > + > + obj_desc->method.mutex->mutex.thread_id = > + acpi_os_get_thread_id(); > } > } > > -- > 1.7.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
