Date: Thu, 17 Apr 2014 12:09:44 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: 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, bp@alien8.de,
        jwboyer@fedoraproject.org, qmewlo@gmail.com, tglx@linutronix.de
Cc: linux-tip-commits@vger.kernel.org
Subject: Re: [tip:x86/urgent] x86/mce: Fix CMCI preemption bugs
Message-ID: <20140417100944.GG11096@twins.programming.kicks-ass.net>
References: <tip-ea431643d6c38728195e2c456801c3ef66bb9991@git.kernel.org>
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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.
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