From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ingo Molnar <mingo@elte.hu>
Date: Thu, 28 Feb 2008 19:12:14 +0000
Subject: Re: 2.6.25-rc2-mm1 - boot hangs on ia64
Message-Id: <20080228191214.GA17872@elte.hu>
List-Id: <linux-ia64.vger.kernel.org>
References: <20080227103831.423F.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20080227071118.GA4638@elte.hu> <20080228192509.BDCF.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20080228115041.GA22082@elte.hu> <20080228101343.1b9548e6.akpm@linux-foundation.org>
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To: Andrew Morton <akpm@linux-foundation.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Steven Rostedt <srostedt@redhat.com>, Lee Schermerhorn <Lee.Schermerhorn@hp.com>, linux-ia64 <linux-ia64@vger.kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, Tony Luck <tony.luck@intel.com>, Ingo Molnar <mingo@redhat.com>, Bob Picco <bob.picco@hp.com>, Eric Whitney <eric.whitney@hp.com>


* Andrew Morton <akpm@linux-foundation.org> wrote:

> On Thu, 28 Feb 2008 12:50:41 +0100 Ingo Molnar <mingo@elte.hu> wrote:
> 
> > @@ -1000,7 +1001,7 @@ void release_console_sem(void)
> >  	 * If we try to wake up klogd while printing with the runqueue lock
> >  	 * held, this will deadlock.
> >  	 */
> > -	if (wake_klogd && !runqueue_is_locked())
> > +	if (wake_klogd)
> >  		wake_up_klogd();
> >  }
> 
> I don't think we shoudl have added that hack in the first place.  It 
> solves a problem which about three developers hit four times in five 
> years but it has made kernel logging less reliable for everyone.

well, the problem was ia64, not a problem on x86 or other platforms. The 
problem here is ia64 not setting up percpu data structures soon enough. 
It has blown up in the past in other areas, and it will likely blow up 
in the future in other areas as well. It's just not robust to have init 
dependencies on such basic data structures like percpu areas like that.

	Ingo