linux-kernel - Re: [PATCH] x86/mce: Keep quiet in case of broadcasted mce after system panic

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Date:   Tue, 24 Jan 2017 10:33:26 +0800
From:   Xunlei Pang <xpang@...hat.com>
To:     Borislav Petkov <bp@...en8.de>, "Luck, Tony" <tony.luck@...el.com>
Cc:     Prarit Bhargava <prarit@...hat.com>,
        Kiyoshi Ueda <k-ueda@...jp.nec.com>, xlpang@...hat.com,
        x86@...nel.org, kexec@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Junichi Nomura <j-nomura@...jp.nec.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Dave Young <dyoung@...hat.com>
Subject: Re: [PATCH] x86/mce: Keep quiet in case of broadcasted mce after
 system panic

On 01/24/2017 at 02:14 AM, Borislav Petkov wrote:
> On Mon, Jan 23, 2017 at 10:01:53AM -0800, Luck, Tony wrote:
>> will ignore the machine check on the other cpus ... assuming
>> that "cpu_is_offline(smp_processor_id())" does the right thing
>> in the kexec case where this is an "old" cpu that isn't online
>> in the new kernel.
> Nice. And kdump did do the dumping on one CPU, AFAIR. So we should be
> good there.
>

"nr_cpus=N" will consume more memory, using very large N is almost
impossible for kdump to boot with considering the limited crash memory
reserved.

For some large machine, nr_cpus=1 might not be enough, we have to use
nr_cpus=4 or more, it is also helpful for the vmcore parallel dumping :-)

Regards,
Xunlei