All of lore.kernel.org
 help / color / mirror / Atom feed
From: Frederic Weisbecker <frederic@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH] kernel/isolation: Asset that a housekeeping CPU comes up at boot time
Date: Mon, 17 Jun 2019 21:05:53 +0200	[thread overview]
Message-ID: <20190617190552.GA10264@lerouge> (raw)
In-Reply-To: <20190617155931.GK3436@hirez.programming.kicks-ass.net>

On Mon, Jun 17, 2019 at 05:59:31PM +0200, Peter Zijlstra wrote:
> On Mon, Jun 10, 2019 at 05:24:32PM +1000, Nicholas Piggin wrote:
> > Nicholas Piggin's on June 1, 2019 9:39 pm:
> > > With the change to allow the boot CPU0 to be isolated, it is possible
> > > to specify command line options that result in no housekeeping CPU
> > > online at boot.
> > > 
> > > An 8 CPU system booted with "nohz_full=0-6 maxcpus=4", for example.
> > > 
> > > It is not easily possible at housekeeping init time to know all the
> > > various SMP options that will result in an invalid configuration, so
> > > this patch adds a sanity check after SMP init, to ensure that a
> > > housekeeping CPU has been onlined.
> > > 
> > > The panic is undesirable, but it's better than the alternative of an
> > > obscure non deterministic failure. The panic will reliably happen
> > > when advanced parameters are used incorrectly.
> > 
> > Ping on this one? This should resolve Frederic's remaining objection
> > to the series (at least until he solves it more generally).
> > 
> > As the series has already been merged, should we get this upstream
> > before release?
> 
> I was hoping for feedback from Frederic, lacking that, I've queued it
> now.
> 

Sorry I just came back from vacation. Any chance we can use a WARN() instead?
I prefer to use panic() only when data is really threatened or such.

Thanks.

  reply	other threads:[~2019-06-17 19:05 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-01 11:39 [PATCH] kernel/isolation: Asset that a housekeeping CPU comes up at boot time Nicholas Piggin
2019-06-10  7:24 ` Nicholas Piggin
2019-06-17 15:59   ` Peter Zijlstra
2019-06-17 19:05     ` Frederic Weisbecker [this message]
2019-06-19  2:40       ` Nicholas Piggin
2019-06-24 10:57 ` Qais Yousef
2019-06-25  0:05   ` Nicholas Piggin

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=20190617190552.GA10264@lerouge \
    --to=frederic@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=npiggin@gmail.com \
    --cc=peterz@infradead.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.