Re: failing kthread_create_on_node()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


David Miller wrote:
From: Konrad Eisele<konrad@xxxxxxxxxxx>
Date: Tue, 17 Apr 2012 08:37:50 +0200

2. What happens next

    CPU1 will boot up and execute schedule().
    ...
    ->  kernel/core.c:__schedule()

The stop thread doesn't actually run immediately when it is created,
so will need to be woken up to be scheduled and run.

At wakeup time, set_task_cpu() should fix things up and make the
task have a correct ->cpu in it's thread_info.

I wonder if one of the sparc32 global cpu masks isn't being
initialized properly.
--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



I have posted
"[PATCH 1/1] sparc: task_cpu() for stopper thread on sparc32 returns 0"

I traced it further and you where right, the stop thread of CPU1 was
sleeping.
The reason that the stopper thread for cpu-1 gets inserted into runqueue-0
(which causes fatal failure later on) is traced below:

When CPU1 comes online it is woken up. Then I end up in
the following call path:

-> kernel/sched/core.c():try_to_wake_up():
        ...
1628:	cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
1629:	if (task_cpu(p) != cpu) {
        ...
     -> kernel/sched/core.c:select_task_rq():
          ...
1332:	  int cpu = p->sched_class->select_task_rq(p, sd_flags, wake_flags);
          ...
        -> kernel/sched/stop_task.c:select_task_rq_stop():
            ...
16:         return task_cpu(p); /* stop tasks as never migrate */
            ...


however task_cpu(p) is 0.

The patch posted checks weather a different cpu should be returned in
kernel/sched/stop_task.c:select_task_rq_stop().

Hope that makes sense.

-- Konrad





--
To unsubscribe from this list: send the line "unsubscribe sparclinux" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Linux MIPS Home]     [Kernel Development]     [DCCP]     [Linux ARM Development]     [Linux]     [Photo]     [Yosemite News]     [MIPS Architecture]     [Linux ARM Kernel]     [Linux SCSI]     [Linux x86_64]     [Linux Hams]

  Powered by Linux