From: Don Zickus <dzickus@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
tony.luck@intel.com, seiji.aguchi@hds.com, ak@linux.intel.com,
mjg@redhat.com, levinsasha928@gmail.com
Subject: Re: [PATCH 2/2] x86, reschedule: check to see if system is shutting down
Date: Wed, 15 Feb 2012 10:57:08 -0500 [thread overview]
Message-ID: <20120215155708.GK9751@redhat.com> (raw)
In-Reply-To: <1329317835.2293.133.camel@twins>
On Wed, Feb 15, 2012 at 03:57:15PM +0100, Peter Zijlstra wrote:
> On Wed, 2012-02-15 at 09:54 -0500, Don Zickus wrote:
> > On Wed, Feb 15, 2012 at 12:26:37PM +0100, Peter Zijlstra wrote:
> > >
> > > Right, so this fixes this one particular case, I imagine there's tons of
> > > places that could go splat due to this (but don't quite yet for some
> > > reason).
> > >
> > > We can't go around annotating everything, nor would we want to simply
> > > shut up all warnings for fear of missing an actual error.
> > >
> > > Why can't the normal shut-down path use a less crazy approach to going
> > > down?
> >
> > Well maybe it can, it's been like that way for over three years now. I'm
> > surprised no one ran into issues before now.
> >
> > The only thing I can think that would work is stop_machine(). Pass in a
> > halt function and a cpumask of everyone but smp_processor_id(). That
> > would solve the problem, no?
>
> nope.. same problem, you're not telling anybody you're shooting CPUs
> down -- this telling is usually done through cpu hotplug notifiers that
> fix up state.
Why? If you have successfully sync'd up the cpus, stopped them and then
run a 'stop_cpu' function, you stop all those WARN_ONs I would think. And
how much do we care that we fix up the state on a shutdown? We have
already shutdown all the processes and unmounted the disks? Most of the
drivers have probably been shutdown cleanly. What is left that we have to
be polite?
>
> The only way is to unplug all cpus except the one. Problem with that is
> that we cannot (as of yet) unplug the boot cpu.
Yeah, well we can migrate to the boot cpu. I think powerpc does that for
kdump.
Cheers,
Don
next prev parent reply other threads:[~2012-02-15 15:57 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-13 20:27 [PATCH 0/2 v2] x86, reboot: cleanup NMI and REBOOT_IRQ Don Zickus
2012-02-13 20:27 ` [PATCH 1/2] x86, reboot: revert stop_other_cpus to using IRQ with NMI fallback Don Zickus
2012-03-02 20:41 ` Seiji Aguchi
2012-03-02 21:11 ` Don Zickus
2012-03-02 21:55 ` Seiji Aguchi
2012-02-13 20:27 ` [PATCH 2/2] x86, reschedule: check to see if system is shutting down Don Zickus
2012-02-13 21:22 ` Seiji Aguchi
2012-02-13 22:43 ` Don Zickus
2012-02-15 11:26 ` Peter Zijlstra
2012-02-15 14:54 ` Don Zickus
2012-02-15 14:57 ` Peter Zijlstra
2012-02-15 15:57 ` Don Zickus [this message]
2012-02-15 17:59 ` Peter Zijlstra
2012-02-16 3:14 ` Don Zickus
-- strict thread matches above, loose matches on Subject: below --
2012-02-10 21:02 [PATCH 0/2] x86, reboot: cleanup NMI and REBOOT_IRQ Don Zickus
2012-02-10 21:02 ` [PATCH 2/2] x86, reschedule: check to see if system is shutting down Don Zickus
2012-02-10 22:42 ` Luck, Tony
2012-02-10 22:53 ` Don Zickus
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120215155708.GK9751@redhat.com \
--to=dzickus@redhat.com \
--cc=ak@linux.intel.com \
--cc=levinsasha928@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mjg@redhat.com \
--cc=peterz@infradead.org \
--cc=seiji.aguchi@hds.com \
--cc=tony.luck@intel.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).