linux-kernel - Re: vmstat: On demand vmstat workers V8

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Message-ID: <53E159F6.7080603@oracle.com>
Date:	Tue, 05 Aug 2014 18:25:58 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Christoph Lameter <cl@...two.org>
CC:	akpm@...ux-foundation.org, Gilad Ben-Yossef <gilad@...yossef.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Tejun Heo <tj@...nel.org>, John Stultz <johnstul@...ibm.com>,
	Mike Frysinger <vapier@...too.org>,
	Minchan Kim <minchan.kim@...il.com>,
	Hakan Akkan <hakanakkan@...il.com>,
	Max Krasnyansky <maxk@...lcomm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, hughd@...gle.com,
	viresh.kumar@...aro.org, hpa@...or.com, mingo@...nel.org,
	peterz@...radead.org
Subject: Re: vmstat: On demand vmstat workers V8

On 08/05/2014 10:51 AM, Christoph Lameter wrote:
> On Mon, 4 Aug 2014, Sasha Levin wrote:
> 
>> On 07/25/2014 10:22 PM, Sasha Levin wrote:
>>> On 07/10/2014 10:04 AM, Christoph Lameter wrote:
>>>>> This patch creates a vmstat shepherd worker that monitors the
>>>>> per cpu differentials on all processors. If there are differentials
>>>>> on a processor then a vmstat worker local to the processors
>>>>> with the differentials is created. That worker will then start
>>>>> folding the diffs in regular intervals. Should the worker
>>>>> find that there is no work to be done then it will make the shepherd
>>>>> worker monitor the differentials again.
>>> Hi Christoph, all,
>>>
>>> This patch doesn't interact well with my fuzzing setup. I'm seeing
>>> the following:
>>
>> I think we got sidetracked here a bit, I've noticed that this issue
>> is still happening in -next and discussions here died out.
> 
> Ok I saw in another thread that this issue has gone away. Is there an
> easy way to reproduce this on my system?
> 

I don't see the VM_BUG_ON anymore, but the cpu warnings are still there.

I can easily trigger it by cranking up the cpu hotplug code. Just try to
frequently offline and online cpus, it should reproduce quickly.


Thanks,
Sasha
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