On Friday, June 21, 2013 10:37:47 AM Alexander E. Patrakov wrote:
> 2013/6/21 Alexander E. Patrakov <patrakov@xxxxxxxxx>:
> > The initial dock went OK. The subsequent undock resulted in the blue
> > led on the dock cable turning off quickly, but in PCI devices slowly,
> > one-by-one, disappearing from the bus. Also, there were "acpi_handle
> > corrupt" messages in dmesg. The subsequent dock resulted in no devices
> > added to the bus. So - your patch is not a good replacement for
> > patches 2 and 3 in the original series.
>
> In this state, echo 1 > /sys/bus/pci/rescan resulted in a kernel BUG,
> see the attached dmesg.
This one is much more interesting than the previous one.
So first of all we have a deadlock related to the
flush_workqueue(kacpi_notify_wq) in acpi_os_wait_events_complete(). I beleve
it is related to the removal of a notify handler in cleanup_bridge().
[ 242.063120] INFO: task kworker/0:0:4 blocked for more than 120 seconds.
[ 242.063124] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 242.063126] kworker/0:0 D ffff8802540adf40 0 4 2 0x00000000
[ 242.063134] Workqueue: kacpi_hotplug _handle_hotplug_event_func
[ 242.063136] ffff8802540d3828 0000000000000046 ffff8802540ae6d8 4ba25e032c97a1cb
[ 242.063139] ffff8802540d3738 ffff8802540d3fd8 ffff8802540d3fd8 0000000000004000
[ 242.063142] ffffffff81c11440 ffff8802540adf40 ffff8802540d3758 ffffffff8109cadb
[ 242.063145] Call Trace:
[ 242.063150] [<ffffffff8109cadb>] ? add_lock_to_list.isra.20.constprop.37+0x7b/0xc0
[ 242.063152] [<ffffffff8109fcc5>] ? __lock_acquire+0x1265/0x1ee0
[ 242.063156] [<ffffffff8101020a>] ? save_stack_trace+0x2a/0x50
[ 242.063159] [<ffffffff8165f764>] schedule+0x24/0x70
[ 242.063163] [<ffffffff8165cab5>] schedule_timeout+0x205/0x260
[ 242.063165] [<ffffffff810a1841>] ? mark_held_locks+0x61/0x150
[ 242.063169] [<ffffffff81059deb>] ? flush_workqueue_prep_pwqs+0x6b/0x1b0
[ 242.063171] [<ffffffff816611ab>] ? _raw_spin_unlock_irq+0x2b/0x60
[ 242.063174] [<ffffffff810a1a35>] ? trace_hardirqs_on_caller+0x105/0x1d0
[ 242.063176] [<ffffffff8165ea74>] wait_for_common+0x114/0x170
[ 242.063179] [<ffffffff8165e195>] ? __mutex_unlock_slowpath+0xf5/0x1a0
[ 242.063182] [<ffffffff810742a0>] ? try_to_wake_up+0x310/0x310
[ 242.063185] [<ffffffff8165eae8>] wait_for_completion+0x18/0x20
[ 242.063187] [<ffffffff8105abca>] flush_workqueue+0x1ca/0x6c0
[ 242.063190] [<ffffffff8105aa00>] ? wq_cpumask_show+0x80/0x80
[ 242.063193] [<ffffffff814380a5>] ? dev_vprintk_emit+0x55/0x70
[ 242.063196] [<ffffffff813a0260>] ? handle_hotplug_event_func+0x80/0x80
[ 242.063199] [<ffffffff813bfd67>] acpi_os_wait_events_complete+0x1c/0x1e
[ 242.063202] [<ffffffff813d31e2>] acpi_remove_notify_handler+0x40/0x178
[ 242.063204] [<ffffffff813a0ef8>] acpiphp_remove_slots+0x88/0x200
[ 242.063207] [<ffffffff813a5c15>] acpi_pci_remove_bus+0x15/0x20
[ 242.063210] [<ffffffff815335d9>] pcibios_remove_bus+0x9/0x10
[ 242.063215] [<ffffffff81380881>] pci_remove_bus+0x41/0x60
[ 242.063217] [<ffffffff813808eb>] pci_remove_bus_device+0x4b/0xe0
[ 242.063219] [<ffffffff813808db>] pci_remove_bus_device+0x3b/0xe0
[ 242.063222] [<ffffffff813808db>] pci_remove_bus_device+0x3b/0xe0
[ 242.063224] [<ffffffff813808db>] pci_remove_bus_device+0x3b/0xe0
[ 242.063226] [<ffffffff81380999>] pci_stop_and_remove_bus_device+0x19/0x20
[ 242.063229] [<ffffffff813a1236>] acpiphp_disable_slot+0x86/0x140
[ 242.063231] [<ffffffff813a1622>] _handle_hotplug_event_func+0x102/0x1e0
[ 242.063234] [<ffffffff8105c2c2>] process_one_work+0x1c2/0x560
[ 242.063236] [<ffffffff8105c257>] ? process_one_work+0x157/0x560
[ 242.063238] [<ffffffff8105d1d6>] worker_thread+0x116/0x370
[ 242.063241] [<ffffffff8105d0c0>] ? manage_workers.isra.20+0x2d0/0x2d0
[ 242.063243] [<ffffffff81063a36>] kthread+0xd6/0xe0
[ 242.063245] [<ffffffff816611ab>] ? _raw_spin_unlock_irq+0x2b/0x60
[ 242.063248] [<ffffffff81063960>] ? __init_kthread_worker+0x70/0x70
[ 242.063251] [<ffffffff8166856c>] ret_from_fork+0x7c/0xb0
[ 242.063253] [<ffffffff81063960>] ? __init_kthread_worker+0x70/0x70
[ 242.063255] 4 locks held by kworker/0:0/4:
[ 242.063256] #0: (kacpi_hotplug){.+.+.+}, at: [<ffffffff8105c257>] process_one_work+0x157/0x560
[ 242.063262] #1: ((&hp_work->work)){+.+.+.}, at: [<ffffffff8105c257>] process_one_work+0x157/0x560
[ 242.063266] #2: (acpi_scan_lock){+.+.+.}, at: [<ffffffff813c3ac6>] acpi_scan_lock_acquire+0x12/0x14
[ 242.063272] #3: (&slot->crit_sect){+.+.+.}, at: [<ffffffff813a11d0>] acpiphp_disable_slot+0x20/0x140
And that is the source of the subsequent re-dock failure (the event cannot be
processed due to the workqueue being stuck). I don't know why this happens at
the moment, but I'm going to figure out.
And the BUG is because we pass a NULL pointer to sysfs_create_bin_file()
somewhere in pci_create_sysfs_dev_files(), but again I don't know why exactly
at the moment.
Let's communicate further in bug #59501.
Thanks,
Rafael
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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