On 04/26, Gautham R Shenoy wrote: > > On Wed, Apr 25, 2007 at 04:54:10PM -0700, Andrew Morton wrote: > > On Thu, 26 Apr 2007 01:10:21 +0200 "Rafael J. Wysocki" <[EMAIL PROTECTED]> > > wrote: > > > > > Hi, > > > > > > The BUG_ON in khthread_bind (line 165 in kthread.c) triggers for me during > > > attempted suspend to disk, when disable_nonboot_cpus() calls _cpu_down() > > > (on x86_64). > > > Caused due to Oleg's patch http://lkml.org/lkml/2007/4/13/93. > > Agreed that most of the time a kthread_create(p) is followed by a > kthread_bind(p), in which case the assertion > WARN_ON(p->state != TASK_UNINTERRUPTIBLE) makes sense. > > But, in cpu hotplug case, we need to rebind the stop_machine_run thread > from the cpu which has just been offlined to any online cpu. > (kernel/cpu.c line 180)
I can't understand why do we need to re-bind this thread. We are doing kthread_stop()->wake_up() below, at this point move_task_off_dead_cpu() has already cared about this task, no? > We only need to ensure in kthread_bind that the task which is being > bound is not running or exiting. Doesn't matter if it's sleeping in > TASK_INTERRUPTIBLE or TASK_UNINTERRUPTIBLE state. We need to ensure that this task can't be woken after return from wait_task_inactive(k), otherwise set_task_cpu() after that is not safe. TASK_INTERRUPTIBLE doesn't protect us from freezing. Couldn't we just remove this kthread_bind() ? Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
