lkml.org 
[lkml]   [2012]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectIn many cases softlockup can not be reported after disabling IRQ for long time
    From
    Resend with a new subject

    On Wed, Jan 25, 2012 at 4:24 PM, TAO HU <tghk48@motorola.com> wrote:
    > Hi, All
    >
    > While playing kernel 3.0.8 with below test code, it does NOT report
    > any softlockup with 60%~70% chances.
    > NOTE: the softlockup timeout is set to 10 seconds (i.e.
    > watchdog_thresh=5) in my test.
    > ... ...
    > preempt_disable();
    > local_irq_disable();
    > for (i = 0; i < 20; i++)
    >       mdelay(1000);
    > local_irq_enable();
    > preempt_enable();
    > ... ...
    >
    > However, if I remove local_irq_disable()/local_irq_enable() it will
    > report softlockup with no problem.
    > I believe it is due to that after local_irq_enable()
    > touch_softlockup_watchdog() is called prior softlockup timer.
    >
    > touch_softlockup_watchdog() basically resets the lockup detection
    > process which implies that the 20-second lockup will be ignored.
    > I noticed that touch_softlockup_watchdog() is called in dozens of
    > places in kernel.
    >
    > Is that a design limitation or a bug? Any way to improve the situation?
    >
    > kernel/debug/debug_core.c:453:  touch_softlockup_watchdog_sync();
    > kernel/power/hibernate.c:443:   touch_softlockup_watchdog();
    > kernel/panic.c:153:             touch_softlockup_watchdog();
    > kernel/time/timekeeping.c:684:  touch_softlockup_watchdog();
    > kernel/time/tick-sched.c:149:   touch_softlockup_watchdog();
    > kernel/time/tick-sched.c:543:   touch_softlockup_watchdog();
    > kernel/time/tick-sched.c:596:           touch_softlockup_watchdog();
    > kernel/time/tick-sched.c:756:                   touch_softlockup_watchdog();
    > kernel/sched_clock.c:277:       touch_softlockup_watchdog();
    >
    >
    >
    > --
    > Best Regards
    > Hu Tao



    --
    Best Regards
    Hu Tao
    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2012-01-31 08:37    [W:0.025 / U:0.076 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site