From: Frederic Weisbecker <fweisbec@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Suresh Siddha <suresh.b.siddha@intel.com>
Subject: Re: [BUG] kernel freezes with latest tree
Date: Wed, 11 Jan 2012 15:20:14 +0100 [thread overview]
Message-ID: <20120111142011.GA7991@somewhere.redhat.com> (raw)
In-Reply-To: <CA+55aFwYmX7q4MZc-xOStZB2ZQjVt_Jca6qDP+0cPKekz8yL+A@mail.gmail.com>
On Tue, Jan 10, 2012 at 03:44:38PM -0800, Linus Torvalds wrote:
> On Tue, Jan 10, 2012 at 2:23 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> >
> > Maybe a recent change in NMI handling, or perf events ?
>
> Unlikely. And it shouldn't show up in the merge commit anyway, those
> things should be pretty independent.
>
> > No idea why the bisection (I redid it carefully : same result) points to the above commit.
>
> Ok, so the bisect is almost certainly correct. But just to be anal and
> really careful, can you independently check both parents of the merge,
> and then re-check the merge itself, and verify that the two parent
> commits never hang, and that the merged state hangs.
>
> Just to take any bisection issues out of the picture, and just verify
> those three commits by hand.
>
> But in the meantime, we should assume that it's the merge that is the problem.
>
> I added Frederic to the cc, because he did the
> tick_nohz_idle_enter_norcu(), so maybe he can tell if there is
> something in that merge that looks suspicious (Frederic - see the
> history of the thread on lkml. I thought maybe it was the lack of
> irq-disable around set_cpu_sd_state_idle(), but Eric already tested
> that). And Suresh because he worked on the whole nohz/nr_busy_cpus.
> Maybe you guys see some obvious semantic clash..
As the thread evolved I guess we found the issue or at least we
got more clues.
But just in case, I double checked the merge but nothing looked
suspicious to me.
Thanks.
>
> Anybody? Any ideas? Clearly there can be a merge problem that doesn't
> actually show as a real data conflict, just some semantic conflict,
> but I don't see what such issues would be brouht in by the scheduler
> merge anyway.
>
> Linus
next prev parent reply other threads:[~2012-01-11 14:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-10 4:57 [BUG] kernel freezes with latest tree Eric Dumazet
2012-01-10 5:03 ` Eric Dumazet
2012-01-10 8:16 ` Eric Dumazet
2012-01-10 16:13 ` Eric Dumazet
2012-01-10 16:28 ` Linus Torvalds
2012-01-10 16:37 ` Eric Dumazet
2012-01-10 16:49 ` Linus Torvalds
2012-01-10 16:53 ` Eric Dumazet
2012-01-10 17:00 ` Linus Torvalds
2012-01-10 19:32 ` Ingo Molnar
2012-01-10 22:23 ` Eric Dumazet
2012-01-10 23:44 ` Linus Torvalds
2012-01-11 6:35 ` David Ahern
2012-01-11 9:04 ` Peter Zijlstra
2012-01-11 10:28 ` Eric Dumazet
2012-01-11 11:29 ` Eric Dumazet
2012-01-11 12:25 ` Peter Zijlstra
2012-01-11 13:24 ` Eric Dumazet
2012-01-11 15:56 ` Ingo Molnar
2012-01-11 16:05 ` Peter Zijlstra
2012-01-11 16:14 ` Ingo Molnar
2012-01-11 16:31 ` Linus Torvalds
2012-01-11 16:58 ` Peter Zijlstra
2012-01-12 6:17 ` [tip:sched/urgent] sched: Fix lockup by limiting load-balance retries on lock-break tip-bot for Peter Zijlstra
2012-01-11 8:22 ` [BUG] kernel freezes with latest tree Eric Dumazet
2012-01-11 14:20 ` Frederic Weisbecker [this message]
2012-01-10 16:16 ` Linus Torvalds
2012-01-10 16:33 ` Eric Dumazet
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