linux-kernel - Re: [PATCH V2 2/3] sched: Fix race in idle

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Message-ID: <52FC9CE9.8000700@linaro.org>
Date:	Thu, 13 Feb 2014 11:22:33 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Alex Shi <alex.shi@...aro.org>
CC:	Preeti Murthy <preeti.lkml@...il.com>,
	Peter Zijlstra <peterz@...radead.org>, mingo@...nel.org,
	LKML <linux-kernel@...r.kernel.org>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>
Subject: Re: [PATCH V2 2/3] sched: Fix race in idle_balance()

On 02/13/2014 11:10 AM, Preeti U Murthy wrote:
> Hi,
>
> On 02/13/2014 01:15 PM, Alex Shi wrote:
>> On 02/11/2014 07:11 PM, Daniel Lezcano wrote:
>>> On 02/10/2014 10:24 AM, Preeti Murthy wrote:
>>>> HI Daniel,
>>>>
>>>> Isn't the only scenario where another cpu can put an idle task on
>>>> our runqueue,
>>>
>>> Well, I am not sure to understand what you meant, but I assume you are
>>> asking if it is possible to have a task to be pulled when we are idle,
>>> right ?
>>>
>>> This patch fixes the race when the current cpu is *about* to enter idle
>>> when calling schedule().
>>
>> Preeti said the she didn't see a possible to insert a task on the cpu.
>>
>> I also did a quick check, maybe task come from wakeup path?
>
> Yes this is possible. Thanks for pointing this :)
>
> Reviewed-by: Preeti U Murthy <preeti@...ux.vnet.ibm.com>

Thanks for the review !

   -- Daniel


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