From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frank Rowand <frank.rowand@am.sony.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
users@kernel.org, hch <hch@infradead.org>,
"yong.zhang0" <yong.zhang0@gmail.com>,
scameron@beardog.cce.hp.com, Jens Axboe <jaxboe@fusionio.com>,
Thomas Gleixner <tglx@linutronix.de>,
"James E.J. Bottomley" <jejb@parisc-linux.org>
Subject: Re: [kernel.org users] [KORG] Panics on master backend
Date: Mon, 29 Aug 2011 16:38:55 +0200 [thread overview]
Message-ID: <20110829143855.GA29953@redhat.com> (raw)
In-Reply-To: <1314623216.2816.25.camel@twins>
On 08/29, Peter Zijlstra wrote:
>
> On Thu, 2011-08-25 at 15:54 +0200, Oleg Nesterov wrote:
> > > Isn't us holding ->pi_lock sufficient to stabilize task_cpu()? If its a
> > > running task the initial ->state check would have failed,
> >
> > Of course it is not TASK_RUNNING, but it can be running or not.
> >
> > > and thus its a
> > > proper wakeup when we get here and thus ->pi_lock is serializing things.
> >
> > I am not sure. If ->on_rq is true, we need rq->lock. Say, pull_task() can
> > change its cpu.
>
> If its !TASK_RUNNING but ->on_rq is true, it must be current, and
> pull_task() will never move current around.
You meant task_running() ? But it can be preempted in !TASK_RUNNING
state.
Oleg.
prev parent reply other threads:[~2011-08-29 14:42 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-23 18:09 [KORG] Panics on master backend J.H.
2011-08-23 19:52 ` [kernel.org users] " Peter Zijlstra
2011-08-23 21:32 ` James Bottomley
2011-08-24 9:59 ` Peter Zijlstra
2011-08-24 16:08 ` Oleg Nesterov
2011-08-25 10:24 ` Peter Zijlstra
2011-08-25 13:54 ` Oleg Nesterov
2011-08-26 6:01 ` Yong Zhang
2011-08-26 13:57 ` Oleg Nesterov
2011-08-29 2:29 ` Yong Zhang
2011-08-29 13:06 ` Peter Zijlstra
2011-08-29 14:38 ` Oleg Nesterov [this message]
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