linux-kernel - Re: [BUGFIX][PATCH] Freezer, CPU hotplug, x86 Microcode: Fix task freezing failures

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Message-ID: <4E8DCDA6.8030802@linux.vnet.ibm.com>
Date:	Thu, 06 Oct 2011 21:17:50 +0530
From:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
To:	Borislav Petkov <bp@...64.org>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>, Borislav Petkov <bp@...en8.de>,
	Tejun Heo <tj@...nel.org>,
	"tigran@...azian.fsnet.co.uk" <tigran@...azian.fsnet.co.uk>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...e.hu" <mingo@...e.hu>, "hpa@...or.com" <hpa@...or.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux PM mailing list <linux-pm@...ts.linux-foundation.org>
Subject: Re: [BUGFIX][PATCH] Freezer, CPU hotplug, x86 Microcode: Fix task
 freezing failures

On 10/06/2011 02:04 PM, Borislav Petkov wrote:
> On Thu, Oct 06, 2011 at 02:50:46AM -0400, Srivatsa S. Bhat wrote:
>> On 10/06/2011 04:13 AM, Rafael J. Wysocki wrote:
>>> On Wednesday, October 05, 2011, Srivatsa S. Bhat wrote:
>>>> On 10/06/2011 01:56 AM, Rafael J. Wysocki wrote:
>>>>>
>>>>> OK, can you please repost the patch with Borislav's Acked-by and Tested-by
>>>>> and add some more Intel people to the CC list?
>>>>>
>>>>
>>>> Sure, I'll do that. Thank you.
>>>> But are we not going to consider a cleaner/correct solution such as the
>>>> one proposed here:
>>>> http://permalink.gmane.org/gmane.linux.kernel/1199494
>>>>
>>>> Well, honestly I don't mean to be stubborn, but somehow, knowing that
>>>> there are issues with my patch doesn't make me feel very comfortable
>>>> going with it, especially when there is another approach, which I
>>>> believe can fix the issue properly, without undesirable side-effects.
>>>>
>>>> I agree that the issues are mostly some corner cases, so if you want a
>>>> quick fix for now, I guess we can go with this patch and then later on
>>>> follow-up with a proper solution to this whole problem.
>>>
>>> It ultimately is your call.  If you feel more comfortable with the
>>> alternative, just post that one instead.
>>>
>> Cool! I am working on implementing that other solution. I'll post it as soon
>> as I am done writing and testing that patch.
> 
> Please test your other patch which removes the CPU_DEAD line from the
> microcode CPU hotplug callback on an Intel box with microcode too and
> submit it. This fix makes sense irrespective of a suspend/resume fix
> because reloading the ucode when onlining the CPU is clearly unneeded.
> 

Ok, I tested both these scenarios on Intel boxes:
1. cpu hotplug stress test + pm_test in parallel
2. loading/unloading microcode etc. 
They all work fine. I'll post that one-line patch with your Acked-by and Tested-by.
Thank you very much.

-- 
Regards,
Srivatsa S. Bhat  <srivatsa.bhat@...ux.vnet.ibm.com>
Linux Technology Center,
IBM India Systems and Technology Lab
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