linux-kernel - Re: [PATCH 4/6] x86-mce: Add spinlocks to prevent duplicated MCP and CMCI reports.

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Message-ID: <87a98inucv.fsf@tassilo.jf.intel.com>
Date:	Wed, 09 Jul 2014 13:35:28 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	Havard Skinnemoen <hskinnemoen@...gle.com>
Cc:	Tony Luck <tony.luck@...el.com>, Borislav Petkov <bp@...en8.de>,
	linux-kernel@...r.kernel.org, Ewout van Bekkum <ewout@...gle.com>
Subject: Re: [PATCH 4/6] x86-mce: Add spinlocks to prevent duplicated MCP and CMCI reports.

Havard Skinnemoen <hskinnemoen@...gle.com> writes:

> machine_check_poll() was modified to use spin_lock_irqsave independently
> per bank when a valid MCE is found to prevent duplicated MCE reports by
> the CMCI and polling methods. In the common case no MCE will be found,
> so the lock is not acquired until a valid MCE is found. The status is
> reread after the lock is acquired in case the MCE was already handled by
> a different thread. A unique spinlock is used per bank number, so
> contention should be mostly limited to non-shared banks.

This doesn't make sense. Banks are either owned by CMCI or by poll,
not by both. If you have true duplicates the bug must be somewhere else.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only
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