Date:	Tue, 08 Jun 2010 16:27:19 +0100
From:	Alan Jenkins <alan-jenkins@...fmail.co.uk>
To:	Kernel Testers List <kernel-testers@...r.kernel.org>
CC:	linux acpi <linux-acpi@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: BUG when battery is removed before resuming from hibernation

Alan Jenkins wrote:
> I found this bug 2.6.34 on my Asus EeePC 701 (x86_32 arch).  It didn't 
> happen to me before, when I was running nearly-2.6.33 or 2.6.32-release.
>
> I used git-bisect, but unfortunately the result isn't very helpful.  
> My next step will be to try to narrowing down the culprits by 
> disabling individual CONFIG options.

Darn, it's not really a regression, or at least not a recent one.  It 
looks like another weird bug that just became more likely for no 
particular reason.

Without recompiling, I simplified the test situation (see below).  I 
then found it reproduced the same BUG on 2.6.32, and also 2.6.31.  
Sometimes I'm getting one of two other BUGs instead, inside 
power_supply_changed_work / kobject_uevent, which cause a hang 
(presumably because these kill "event/0" instead of the ACPI-specific 
workqueue thread).

My old 2.6.30 kernel is immune, but that might be due to config 
differences or somethiing.


1. Boot with init=/bin/bash
2. Remove as many modules as possible (the initramfs loads a few)
3. Load the battery module

4. Run pm-hibernate
 - and insert the battery during hibernation, wait for completion, and 
then remove the battery before resuming again.


Alan

>
> == Steps to reproduce ==
>
> I) Boot off mains power, with battery removed.  Login to KDE4 session, 
> with Konsole as the only running application.
> II) Run "sudo pm-hibernate"
>
> 1. When the system switches to text mode (a.k.a the console), 
> immediately insert the battery.
> 2. Once the system has fully hibernated, remove the battery.
> 3. Press the power button to resume.  The backtrace below is generated 
> during resume.
<snip>

>
> == BUG / Backtrace message ==
>
> The BUG looks a bit like a double-free in the power supply class or 
> the ACPI battery driver.  (6b6b6b6b is apparently the SLAB poison used 
> to mark memory which has been freed).
>
>
> BUG: unable to handle kernel paging request at 6b6b6b6f
> IP: [<c11d8657>] led_trigger_unregister+0x18/0x8a
> *pde = 00000000
> Oops: 0002 [#1] SMP
> last sysfs file: /sys/devices/virtual/vc/vcsa8/uevent
> Modules linked in: i915 drm_kms_helper drm i2c_algo_bit fuse loop 
> joydev arc4 ecb snd_hda_codec_realtek snd_hda_intel snd_hda_codec 
> snd_hwdep snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_midi snd_rawmidi 
> snd_seq_midi_event snd_seq snd_timer ath5k snd_seq_device mac80211 
> uvcvideo eeepc_laptop snd ath videodev v4l1_compat psmouse cfg80211 
> sparse_keymap video intel_agp soundcore i2c_core rfkill serio_raw 
> evdev led_class snd_page_alloc agpgart output battery ac pci_hotplug 
> processor button ext4 mbcache jbd2 crc16 usb_storage sd_mod crc_t10dif 
> uhci_hcd ata_piix ehci_hcd atl2 usbcore thermal thermal_sys [last 
> unloaded: scsi_wait_scan]
>
> Pid: 16, comm: kacpi_notify Not tainted 2.6.34eeepc #109 701/701
> EIP: 0060:[<c11d8657>] EFLAGS: 00010282 CPU: 0
> EIP is at led_trigger_unregister+0x18/0x8a
> EAX: 6b6b6b6b EBX: de70a1e0 ECX: 00000001 EDX: 6b6b6b6b
> ESI: de70a1e0 EDI: 00000001 EBP: df0abe98 ESP: df0abe8c
>  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
> Process kacpi_notify (pid: 16, ti=df0aa000 task=df0a94b0 
> task.ti=df0aa000)
> Stack:
>  de70a1e0 00000000 00000001 df0abea4 c11d86d8 df2ce318 df0abeb0 c11d711c
> <0> df2ce318 df0abebc c11d6b37 df2ce2d8 df0abec8 e0308033 df2ce2d8 
> df0abeec
> <0> e0308369 df02fd00 00000000 df0abef0 c117a8d1 df2ce2d8 df0d4140 
> 00000001
> Call Trace:
>  [<c11d86d8>] ? led_trigger_unregister_simple+0xf/0x19
>  [<c11d711c>] ? power_supply_remove_triggers+0x14/0x4c
>  [<c11d6b37>] ? power_supply_unregister+0x12/0x24
>  [<e0308033>] ? sysfs_remove_battery+0x1f/0x29 [battery]
>  [<e0308369>] ? acpi_battery_update+0x65/0x223 [battery]
>  [<c117a8d1>] ? acpi_get_data+0x51/0x60
>  [<e0308548>] ? acpi_battery_notify+0x21/0x58 [battery]
>  [<c1162eb8>] ? acpi_bus_notify+0xb3/0xba
>  [<c1162e05>] ? acpi_bus_notify+0x0/0xba
>  [<c1170302>] ? acpi_ev_notify_dispatch+0x3b/0x65
>  [<c1160d96>] ? acpi_os_execute_deferred+0x1d/0x28
>  [<c10401f8>] ? worker_thread+0x19a/0x25d
>  [<c10401b6>] ? worker_thread+0x158/0x25d
>  [<c1160d79>] ? acpi_os_execute_deferred+0x0/0x28
>  [<c10438a1>] ? autoremove_wake_function+0x0/0x2f
>  [<c104005e>] ? worker_thread+0x0/0x25d
>  [<c104353e>] ? kthread+0x6a/0x6f
>  [<c10434d4>] ? kthread+0x0/0x6f
>  [<c1002dc2>] ? kernel_thread_helper+0x6/0x1a
> Code: 73 60 8b 56 04 85 d2 74 04 89 d8 ff d2 5a 5b 5e 5f 5d c3 55 89 
> e5 57 56 89 c6 53 b8 44 42 43 c1 e8 95 17 0a 00 8b 56 30 8b 46 34 <89> 
> 42 04 89 10 b8 44 42 43 c1 c7 46 30 00 01 10 00 c7 46 34 00
> EIP: [<c11d8657>] led_trigger_unregister+0x18/0x8a SS:ESP 0068:df0abe8c
> CR2: 000000006b6b6b6f
> ---[ end trace 98ac34cabd457f98 ]---
>

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