Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754185Ab3EMObI (ORCPT ); Mon, 13 May 2013 10:31:08 -0400 Received: from relay1.sgi.com ([192.48.179.29]:50854 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752402Ab3EMObG (ORCPT ); Mon, 13 May 2013 10:31:06 -0400 Date: Mon, 13 May 2013 09:31:04 -0500 From: Robin Holt To: Thomas Gleixner Cc: Robin Holt , Frederic Weisbecker , linux-kernel@vger.kernel.org, Ingo Molnar Subject: Re: Full dynticks needs evtdesc set before marking cpu online. Message-ID: <20130513143104.GG3658@sgi.com> References: <20130508235736.GT3658@sgi.com> <20130513125514.GE3658@sgi.com> <20130513135948.GF3658@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1972 Lines: 45 On Mon, May 13, 2013 at 04:04:45PM +0200, Thomas Gleixner wrote: > On Mon, 13 May 2013, Robin Holt wrote: > > On Mon, May 13, 2013 at 03:03:55PM +0200, Thomas Gleixner wrote: > > > On Mon, 13 May 2013, Robin Holt wrote: > > > > > > > On Mon, May 13, 2013 at 11:21:00AM +0200, Thomas Gleixner wrote: > > > > > On Wed, 8 May 2013, Robin Holt wrote: > > > > > > > > > > > Thomas, > > > > > > > > > > > > We are seeing failures booting medium sized machines which I think is > > > > > > a change in expectations that dyntick put on x86's start_secondary. > > > > > > > > > > > > During boot of cpus, we see an occassional panic in tick_do_broadcast at > > > > > > > > > > http://lkml.indiana.edu/hypermail/linux/kernel/1305.0/01818.html > > > > > > > > > > Will hit Linus tree soon. > > > > > > > > I think this is really due to a sequence in start_secondary. The cpu > > > > has been marked as online, but its evtdesc has not been initialized. > > > > I sent a followup to this with a hack/patch. > > > > > > No, the real issue is that I messed up the cpumask conversion in the > > > broadcast code, i.e. using alloc instead of zalloc, which allocated > > > nonzeroed memory for the cpumasks, so any random bit set will crash > > > the machine. Your patch is just papering over the issue. > > > > I believe I understand now. What would be the downside of moving > > the initialization to before marking the cpu online? It seems like a > > reasonable this to expect as well in spite of it not being the right > > fix to the other bug. > > Yes, we can move it, but its not a required thing that the tick device > is setup befor onlining. I tested with your patch and it does fix my problem as well. Thank your, Robin -- 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/