linux-kernel - Re: [PATCH v2] x86, hotplug: fix llc shared map unreleased during cpu hotplug

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Message-ID: <20140722094425.GC6462@pd.tnic>
Date:	Tue, 22 Jul 2014 11:44:25 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Wanpeng Li <wanpeng.li@...ux.intel.com>
Cc:	"Chen, Gong" <gong.chen@...ux.intel.com>, hpa@...or.com,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	David Rientjes <rientjes@...gle.com>,
	Prarit Bhargava <prarit@...hat.com>,
	Steven Rostedt <srostedt@...hat.com>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	Toshi Kani <toshi.kani@...com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] x86, hotplug: fix llc shared map unreleased during
 cpu hotplug

On Tue, Jul 22, 2014 at 05:30:23PM +0800, Wanpeng Li wrote:
> On Tue, Jul 22, 2014 at 04:46:41AM -0400, Chen, Gong wrote:
> >On Tue, Jul 22, 2014 at 04:04:52PM +0800, Wanpeng Li wrote:
> >> Subject: [PATCH v2] x86, hotplug: fix llc shared map unreleased during cpu
> >>  hotplug
> >
> >See this link:
> >https://lkml.org/lkml/2014/7/17/78
> 
> Interesting, thanks for your pointing out.

Well, we might end up doing both.

Yasuaki's patch makes the core numbering stable which makes a lot of
sense in and of itself.

However, if some code somewhere relies implicitly on the fact that a set
bit in LLC mask means that core is online and goes and does stuff on it,
Wanpeng's reported splat will happen.

So probably we will have to have *stable* core numbers *and* clear the
LLC mask in order to be on the safe side of things.

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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