Messages in this thread | | | Subject | Re: [BUG 2.6.25-rc3] scheduler/hotplug: some processes are dealocked when cpu is set to offline | From | Yi Yang <> | Date | Mon, 03 Mar 2008 22:45:04 +0800 |
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On Mon, 2008-03-03 at 21:01 +0530, Gautham R Shenoy wrote: > > This issue seems such one, but i tried to change it to follow this rule but > > the issue is still there. > > > > Why isn't the kernel thread [watchdog/1] reaped by its parent? its state > > is TASK_RUNNING with high priority (R< means this), why it isn't done? > > > > Anyone ever met such a problem? Your thought? > > Hi Yi, > > This is indeed strange. I am able to reproduce this problem on my 4-way > box. From what I see in the past two runs, we're waiting in the > cpu-hotplug callback path for the watchdog/1 thread to stop. > > During cpu-offline, once the cpu goes offline, in the migration_call(), > we migrate any tasks associated with the offline cpus > to some other cpu. This also mean breaking affinity for tasks which were > affined to the cpu which went down. So watchdog/1 has been migrated to > some other cpu. No, [watchdog/1] is just for CPU #1, if CPU #1 has been offline, it should be killed but not migrated to other CPU because other CPU has such a kthread.
Maybe migration_call was doing such a bad thing. :-) > > However, it remains in R< state and has not executed the > kthread_should_stop() instruction. > > I'm trying to probe further by inserting a few more printk's in there. > > Will post the findings in a couple of hours. > > Thanks for reporting the problem. > > Regards > gautham.
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