linux-kernel - Re: [Patch V0] x86, mce: Ensure offline CPU's don't participate in mce rendezvous process.

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Message-ID: <20151203233453.GA15933@kroah.com>
Date:	Thu, 3 Dec 2015 15:34:53 -0800
From:	Greg KH <greg@...ah.com>
To:	Ashok Raj <ashok.raj@...el.com>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	linux-edac@...r.kernel.org, Boris Petkov <bp@...e.de>,
	Tony Luck <tony.luck@...el.com>
Subject: Re: [Patch V0] x86, mce: Ensure offline CPU's don't participate in
 mce rendezvous process.

On Thu, Dec 03, 2015 at 07:16:10PM -0500, Ashok Raj wrote:
> Linux has logical cpu offline capability. That can be triggered by:
> 
> # echo 0 > /sys/devices/system/cpu/cpuX/online
> 
> In Intel Architecture, MCE's are broadcasted to all CPUs in the system.
> 
> This includes the CPUs marked offline by Linux. Unless the CPU's were removed
> via an ACPI notification, in which case the cpu's are removed from the
> cpu_present_map.
> 
> This patch ensures offline CPU's don't participate in MCE rendezvous, but
> simply perform clearing some status bits to ensure a second MCE wont cause
> automatic shutdown.
> 
> Without the patch, mce_start will increment mce_callin, but mce_start would
> wait for all online_cpus. So offline cpu's should avoid participating in the
> rendezvous process.
> 
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> Signed-off-by: Ashok Raj <ashok.raj@...el.com>
> ---
>  arch/x86/kernel/cpu/mcheck/mce.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>
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