Re: [Bugme-new] [Bug 15005] New: Segmentation fault when shuttingdown

From: Xiaotian Feng
Date: Tue Jan 12 2010 - 21:08:55 EST

I'm not sure, but I can't see the start of the seg fault. Is it a kernel NULL pointer deref or trigger the BUG?
Mind to try patch in

On 01/13/2010 06:07 AM, Andrew Morton wrote:

(switched to email. Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Thu, 7 Jan 2010 20:59:20 GMT
bugzilla-daemon@xxxxxxxxxxxxxxxxxxx wrote:

Summary: Segmentation fault when shutting down
Product: ACPI
Version: 2.5
Kernel Version:
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: blocking
Priority: P1
Component: Power-Off
AssignedTo: acpi_power-off@xxxxxxxxxxxxxxxxxxxx
ReportedBy: mrb74@xxxxxx
Regression: Yes

Created an attachment (id=24479)
--> (
Screenshot of segmentation fault

Currently compiled newest kernel for Atom based netbook (datacask
Jupiter 1014a). Compiled the kernel with optimizations for Atom CPUs and also
with optimizations for i586.
When shutting down the system the kernel produces a segmentation fault at the
end of the shutdown process. Powering off fails. Both kernel fail with the same
Last working kernel was

It's a shutdown-time oops in clockevents_notify(). A -> regression. included this prime suspect:

: commit fa3f5a5c1c8e6a2cbc7e21755ea7c215f8cf0577
: Author: Thomas Gleixner<tglx@xxxxxxxxxxxxx>
: Date: Thu Dec 10 15:35:10 2009 +0100
: clockevents: Prevent clockevent_devices list corruption on cpu hotplug
: commit bb6eddf7676e1c1f3e637aa93c5224488d99036f upstream.
: which

So we may well have the same regression in 2.6.33-rcX.

Martin, can you please check whether the below revert fixes things up?


From: Andrew Morton<akpm@xxxxxxxxxxxxxxxxxxxx>


: commit bb6eddf7676e1c1f3e637aa93c5224488d99036f
: Author: Thomas Gleixner<tglx@xxxxxxxxxxxxx>
: AuthorDate: Thu Dec 10 15:35:10 2009 +0100
: Commit: Thomas Gleixner<tglx@xxxxxxxxxxxxx>
: CommitDate: Fri Dec 11 10:28:08 2009 +0100
: clockevents: Prevent clockevent_devices list corruption on cpu hotplug

due to the regression reported in

Cc: Xiaotian Feng<dfeng@xxxxxxxxxx>
Cc: Thomas Gleixner<tglx@xxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki"<rjw@xxxxxxx>
Reported-by: Martin Bammer<mrb74@xxxxxx>
Signed-off-by: Andrew Morton<akpm@xxxxxxxxxxxxxxxxxxxx>

kernel/time/clockevents.c | 18 +++---------------
1 file changed, 3 insertions(+), 15 deletions(-)

diff -puN kernel/time/clockevents.c~revert-clockevents-prevent-clockevent_devices-list-corruption-on-cpu-hotplug kernel/time/clockevents.c
--- a/kernel/time/clockevents.c~revert-clockevents-prevent-clockevent_devices-list-corruption-on-cpu-hotplug
+++ a/kernel/time/clockevents.c
@@ -238,9 +238,8 @@ void clockevents_exchange_device(struct
void clockevents_notify(unsigned long reason, void *arg)
- struct clock_event_device *dev, *tmp;
+ struct list_head *node, *tmp;
unsigned long flags;
- int cpu;

raw_spin_lock_irqsave(&clockevents_lock, flags);
clockevents_do_notify(reason, arg);
@@ -251,19 +250,8 @@ void clockevents_notify(unsigned long re
* Unregister the clock event devices which were
* released from the users in the notify chain.
- list_for_each_entry_safe(dev, tmp,&clockevents_released, list)
- list_del(&dev->list);
- /*
- * Now check whether the CPU has left unused per cpu devices
- */
- cpu = *((int *)arg);
- list_for_each_entry_safe(dev, tmp,&clockevent_devices, list) {
- if (cpumask_test_cpu(cpu, dev->cpumask)&&
- cpumask_weight(dev->cpumask) == 1) {
- list_del(&dev->list);
- }
- }
+ list_for_each_safe(node, tmp,&clockevents_released)
+ list_del(node);

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