linux-kernel - Re: [PATCH v8] x86: mce: kexec: switch MCE handler for kexec/kdump

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Message-ID: <20150409095308.GG25434@pd.tnic>
Date:	Thu, 9 Apr 2015 11:53:08 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc:	Ingo Molnar <mingo@...nel.org>, Tony Luck <tony.luck@...el.com>,
	Prarit Bhargava <prarit@...hat.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Junichi Nomura <j-nomura@...jp.nec.com>,
	Kiyoshi Ueda <k-ueda@...jp.nec.com>
Subject: Re: [PATCH v8] x86: mce: kexec: switch MCE handler for kexec/kdump

On Thu, Apr 09, 2015 at 08:59:44AM +0000, Naoya Horiguchi wrote:
> I replied about testing. That might be tricky a little, but I hope it helps.

Yeah, whatever we do, we need this properly tested before upstreaming.
That's a given.

> Even if we raise tolerant level in running kdump, that doesn't prevent
> idling CPUs from running MCE handlers when MCE arrives, which makes memory
> accesses (losing information from kdump's viewpoint) and spits
> "MCE synchronization timeout" messages (unclear and confusing for users.)

Why? Those CPUs are offlined and num_online_cpus() in mce_start() should
account for that, no?

And if those are offlined, they're very very unlikely to trigger an MCE
as they're idle and not executing code.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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