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Message-ID: <20080307025451.GA201@tv-sign.ru>
Date: Fri, 7 Mar 2008 05:54:51 +0300
From: Oleg Nesterov <oleg@...sign.ru>
To: Gautham R Shenoy <ego@...ibm.com>
Cc: Yi Yang <yi.y.yang@...el.com>, Ingo Molnar <mingo@...e.hu>,
akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
"Rafael J. Wysocki" <rjw@...k.pl>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [BUG 2.6.25-rc3] scheduler/hotplug: some processes are dealocked when cpu is set to offline
On 03/06, Gautham R Shenoy wrote:
>
> On Tue, Mar 04, 2008 at 06:01:07PM +0300, Oleg Nesterov wrote:
> > +static void check_running_task(struct task_struct *t, unsigned long now)
> > +{
> > + if (!sysctl_hung_task_timeout_secs)
> > + return;
> > +
>
> This function gets called only when t->xxx == 0,
> so the if below doesn't mean much, does it? :)
>
> > + if (time_before(now, t->xxx + HZ * sysctl_hung_task_timeout_secs)
> > + return;
> .......
>
> > @@ -192,15 +214,17 @@ static void check_hung_uninterruptible_t
> > if ((tainted & TAINT_DIE) || did_panic)
> > return;
> >
> > - read_lock(&tasklist_lock);
> > + rcu_read_lock();
> > do_each_thread(g, t) {
> > if (!--max_count)
> > goto unlock;
> > if (t->state & TASK_UNINTERRUPTIBLE)
> > check_hung_task(t, now);
> > + if (!t->xxx)
> > + check_running_task(t, jiff);
Of course, the check above should be
if (1t->xxx)
check_running_task(t, jiff);
Thanks!
>From another message,
>
> Me too. With your patch applied there were quite a few tasks in the
> running state which didn't get the cpu for more than 120 seconds.
(I assume you fixed the patch before using it ;)
Just to be sure, there were no "bad ->cpu..." messages, yes?
Oleg.
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