linux-kernel - Re: [PATCH v2 1/2] x86: mce: kexec: turn off MCE in kexec

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Message-ID: <20150302163216.GF17521@pd.tnic>
Date:	Mon, 2 Mar 2015 17:32:16 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Naoya Horiguchi <nao.horiguchi@...il.com>
Cc:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	"Luck, Tony" <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 v2 1/2] x86: mce: kexec: turn off MCE in kexec

On Mon, Mar 02, 2015 at 11:33:33PM +0900, Naoya Horiguchi wrote:
> Yes, CPU offlining is one option to keep other CPUs quiet. I'm not sure why
> current kexec implementation doesn't offline the other CPUs but just doing
> cpu_relax() loop, but my guess is that in some kernel panic situation (like
> soft lockup) we want to keep CPUs' status undisturbed to make sure the bug's
> info is captured in kdump.

Well either offlining or keeping them in the idle loop is fine - they're
not executing anything else and thus the probability of them causing an
MCE becomes disappearingly small.

-- 
Regards/Gruss,
    Boris.

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