linux-kernel - RE: [PATCH] x86, MCE: Kill CPU_POST

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Date:	Thu, 22 May 2014 15:50:21 +0000
From:	"Luck, Tony" <tony.luck@...el.com>
To:	Borislav Petkov <bp@...en8.de>,
	Peter Zijlstra <peterz@...radead.org>
CC:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Borislav Petkov <bp@...e.de>, Ingo Molnar <mingo@...nel.org>,
	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"ego@...ux.vnet.ibm.com" <ego@...ux.vnet.ibm.com>,
	Oleg Nesterov <oleg@...hat.com>
Subject: RE: [PATCH] x86, MCE: Kill CPU_POST_DEAD

>> So I think we can reduce it to just the one rwsem (with recursion) if we
>> shoot CPU_POST_DEAD in the head.
>
> Here's the first bullet. Stressing my box here with Steve's hotplug
> script seems to work fine.
>
> Tony, any objections?

what was this comment referring to:

    /* intentionally ignoring frozen here */

After you move the cmci_rediscover() call, it is now in a place where we are
no longer ignoring frozen (i.e. the old placement did the rediscover even if the
CPU_TASKS_FROZEN bit was set - with the new placement we will skip rediscovery.

So we were working around some interaction between cpu hotplug and frozen.
Do we no longer need to do that?

-Tony