From: Robin Holt <holt@sgi.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Robin Holt <holt@sgi.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>
Subject: Re: Full dynticks needs evtdesc set before marking cpu online.
Date: Mon, 13 May 2013 08:59:48 -0500 [thread overview]
Message-ID: <20130513135948.GF3658@sgi.com> (raw)
In-Reply-To: <alpine.LFD.2.02.1305131501210.2863@ionos>
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.
Thanks,
Robin
next prev parent reply other threads:[~2013-05-13 13:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-08 23:57 Full dynticks needs evtdesc set before marking cpu online Robin Holt
2013-05-12 20:16 ` Frederic Weisbecker
2013-05-13 9:21 ` Thomas Gleixner
2013-05-13 12:55 ` Robin Holt
2013-05-13 13:03 ` Thomas Gleixner
2013-05-13 13:59 ` Robin Holt [this message]
2013-05-13 14:04 ` Thomas Gleixner
2013-05-13 14:31 ` Robin Holt
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