linux-kernel - Re: [PATCH] x86/mce: Distirbute the clear operation of mces_seen to Per-CPU rather than only monarch CPU

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Message-ID: <20140518163508.GA8003@pd.tnic>
Date:	Sun, 18 May 2014 18:35:08 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Chen Yucong <slaoub@...il.com>
Cc:	tony.luck@...el.com, linux-kernel@...r.kernel.org,
	linux-edac@...r.kernel.org
Subject: Re: [PATCH] x86/mce: Distirbute the clear operation of mces_seen to
 Per-CPU rather than only monarch CPU

On Sun, May 18, 2014 at 11:05:04PM +0800, Chen Yucong wrote:a
> mces_seen is a Per-CPU variable which should only be accessed by
> Per-CPU as possible. So the clear operation of mces_seen should also
> be lcoal to Per-CPU rather than monarch CPU.

No, you need to do the cleaning in mce_reign because the monarch cpu has
to run last after all other cpus have scanned their mce banks.

> Meanwhile, there is also a potential risk that mces_seen will not
> be be cleared if a timeout occors in mce_end for monarch CPU. As a
> reuslt, the stale value of mces_seen will reappear on the next mce.

If that happens, we have a bigger problem.

Is that a real issue you're trying to address?

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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