From: Borislav Petkov <bp@alien8.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, atodorov@redhat.com,
tony.luck@intel.com, gong.chen@linux.intel.com,
jwboyer@fedoraproject.org, qmewlo@gmail.com, tglx@linutronix.de,
linux-tip-commits@vger.kernel.org
Subject: Re: [tip:x86/urgent] x86/mce: Fix CMCI preemption bugs
Date: Thu, 17 Apr 2014 12:24:42 +0200 [thread overview]
Message-ID: <20140417102442.GA8215@pd.tnic> (raw)
In-Reply-To: <20140417100944.GG11096@twins.programming.kicks-ass.net>
On Thu, Apr 17, 2014 at 12:09:44PM +0200, Peter Zijlstra wrote:
> On Thu, Apr 17, 2014 at 02:57:54AM -0700, tip-bot for Ingo Molnar wrote:
> > Commit-ID: ea431643d6c38728195e2c456801c3ef66bb9991
> > Gitweb: http://git.kernel.org/tip/ea431643d6c38728195e2c456801c3ef66bb9991
> > Author: Ingo Molnar <mingo@kernel.org>
> > AuthorDate: Thu, 17 Apr 2014 10:25:53 +0200
> > Committer: Ingo Molnar <mingo@kernel.org>
> > CommitDate: Thu, 17 Apr 2014 10:28:42 +0200
> >
> > x86/mce: Fix CMCI preemption bugs
> >
> > The following commit:
> >
> > 27f6c573e0f7 ("x86, CMCI: Add proper detection of end of CMCI storms")
> >
> > Added two preemption bugs:
> >
> > - machine_check_poll() does a get_cpu_var() without a matching
> > put_cpu_var(), which causes preemption imbalance and crashes upon
> > bootup.
> >
> > - it does percpu ops without disabling preemption. Preemption is not
> > disabled due to the mistaken use of a raw spinlock.
>
> it is arch_spinlock that doesn't disable preemption. raw_spinlock
> disables preemption just fine.
Hohum, __raw_spin_lock_irqsave does preempt_disable(). And
machine_check_poll should be running in irq context so why would the
original issue happen?
> kernel: [ 7.341085] BUG: using __this_cpu_write() in preemptible [00000000] code: modprobe/546
Unfortunately, I have only one line in a mail CCed to me.
Color me confused.
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
next prev parent reply other threads:[~2014-04-17 10:24 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-17 9:57 [tip:x86/urgent] x86/mce: Fix CMCI preemption bugs tip-bot for Ingo Molnar
2014-04-17 10:09 ` Peter Zijlstra
2014-04-17 10:24 ` Borislav Petkov [this message]
2014-04-17 14:03 ` Luck, Tony
2014-04-17 15:26 ` Borislav Petkov
2014-04-17 16:54 ` Josh Boyer
2014-04-17 19:23 ` Borislav Petkov
2014-04-17 19:25 ` Linus Torvalds
2014-04-17 19:42 ` Borislav Petkov
2014-04-17 20:58 ` Borislav Petkov
[not found] ` <CAK7FoDt6tnknX7cioe7=2svVksyAyLUtoZX_oprzJNxoHZEpdw@mail.gmail.com>
2014-04-17 21:30 ` Borislav Petkov
2014-04-17 22:20 ` Borislav Petkov
2014-04-18 8:07 ` Ingo Molnar
2014-04-18 9:22 ` Borislav Petkov
2014-04-25 8:47 ` Chen, Gong
2014-04-25 13:15 ` Ingo Molnar
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