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

Prarit Bhargava
2015-03-02T16:51:14Z

On 03/02/2015 11:32 AM, Borislav Petkov wrote:
> 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.

Unless entering a deep C state kicks an MCE ... which we've seen with flaky
hardware.

P.

>