Kernel Bug Tracker – Bug 51661
Computer stops working after power supply introduced
Last modified: 2013-01-28 23:20:02 UTC
After upgrading from 3.7-rc8 to 3.7, I can no longer plug in the power supply to my laptop and not freeze everything. Downgrading to 3.7-rc8 fixes the problem.
Steps to reproduce:
1) Install linux 3.7
2) Unplug power supply if connected
3) Plug power supply back in
Computer becomes wholly unresponsive.
Computer should continue working fine.
Build date and platform:
Build Date : Tue 11 Dec 2012 12:30:56 AM CST
Platform : Arch Linux
I ran a git bisect from 3.7-rc8 to 3.7, and this seems to be the offending commit:
8d4516904b39507458bee8115793528e12b1d8dd is the first bad commit
Author: Thomas Gleixner <email@example.com>
Date: Tue Dec 4 18:59:34 2012 +0100
watchdog: Fix CPU hotplug regression
"3.7-rc6 booted with nmi_watchdog=0 fails to suspend to RAM or
offline CPUs. It's reproducable with a KVM guest and physical
The reason is that commit bcd951cf(watchdog: Use hotplug thread
infrastructure) missed to take this into account. So the cpu offline
code gets stuck in the teardown function because it accesses non
initialized data structures.
Add a check for watchdog_enabled into that path to cure the issue.
Reported-and-tested-by: Norbert Warmuth <firstname.lastname@example.org>
Tested-by: Joseph Salisbury <email@example.com>
Signed-off-by: Thomas Gleixner <firstname.lastname@example.org>
:040000 040000 32962c88d16bc0cf841e114b181163c9450dabde dc9ba81b3cf7a8b40f739855dd9c1a08aaa2fbc5 M kernel
I see this too on my Lenovo X220. Probably bug #51721 is a duplicate of this bug.
*** Bug 51721 has been marked as a duplicate of this bug. ***
There seems to be someone else that found the same commit as I did.
Makes sense - I'm running laptop mode.
echo 0 > /proc/sys/kernel/nmi_watchdog
echo 1 > /proc/sys/kernel/nmi_watchdog
results in a kernel panic and disabling laptop-mode-tools works for now.
So if it understand it correctly, this is not yet fixed in Linus' master tree - which means that it is not yet in the upcoming release Linux 3.7.1.
I think the patch posted by Bjørn Mork looks reasonable, thought:
Confirm the same problem on my machine
Seems to have been reverted.
I can conform this bug on two Lenovo machines (U160 + e330) trying the latest kernel v3.7.1. The machines freeze also when they are in standby mode I plug in the power supply and wake them up.
confirmed on my laptop (Dell Latitude E6420), running kernel 3.7.0-7-generic
Created attachment 90661 [details]
3.8-rc1 patch backported to 3.7
try this 3.8-rc1 pach in your 3.7.* kernel
it is marked for .stable, but doesn't appear in 3.7-stable yet.
Bug still exists in 3.7.2.
3.7.3 is now released with the fix for this bug, and everybody should be happy. Enjoy!
Author: Bjørn Mork <email@example.com>
Date: Wed Dec 19 20:51:31 2012 +0100
watchdog: Fix disable/enable regression
commit 3935e89505a1c3ab3f3b0c7ef0eae54124f48905 upstream.
Commit 8d4516904b39 ("watchdog: Fix CPU hotplug regression") causes an
oops or hard lockup when doing