Re: vmstat: On demand vmstat workers V8

From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: Christoph Lameter <cl@gentwo.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	<akpm@linux-foundation.org>,
	Gilad Ben-Yossef <gilad@benyossef.com>,
	Thomas Gleixner <tglx@linutronix.de>, Tejun Heo <tj@kernel.org>,
	John Stultz <johnstul@us.ibm.com>,
	Mike Frysinger <vapier@gentoo.org>,
	Minchan Kim <minchan.kim@gmail.com>,
	Hakan Akkan <hakanakkan@gmail.com>,
	Max Krasnyansky <maxk@qualcomm.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	<linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
	<hughd@google.com>, <viresh.kumar@linaro.org>, <hpa@zytor.com>,
	<mingo@kernel.org>, <peterz@infradead.org>
Subject: Re: vmstat: On demand vmstat workers V8
Date: Wed, 30 Jul 2014 11:04:59 +0800	[thread overview]
Message-ID: <53D860DB.40806@cn.fujitsu.com> (raw)
In-Reply-To: <alpine.DEB.2.11.1407111016040.26485@gentwo.org>

On 07/11/2014 11:17 PM, Christoph Lameter wrote:
> On Fri, 11 Jul 2014, Frederic Weisbecker wrote:
> 
>>> Converted what? We still need to keep a cpumask around that tells us which
>>> processor have vmstat running and which do not.
>>>
>>
>> Converted to cpumask_var_t.
>>
>> I mean we spent dozens emails on that...
> 
> 
> Oh there is this outstanding fix, right.
> 
> 
> Subject: on demand vmstat: Do not open code alloc_cpumask_var
> 
> Signed-off-by: Christoph Lameter <cl@linux.com>
> 
> Index: linux/mm/vmstat.c
> ===================================================================
> --- linux.orig/mm/vmstat.c	2014-07-11 10:15:55.356856916 -0500
> +++ linux/mm/vmstat.c	2014-07-11 10:15:55.352856994 -0500
> @@ -1244,7 +1244,7 @@
>  #ifdef CONFIG_SMP
>  static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
>  int sysctl_stat_interval __read_mostly = HZ;
> -struct cpumask *cpu_stat_off;
> +cpumask_var_t cpu_stat_off;
> 
>  static void vmstat_update(struct work_struct *w)
>  {
> @@ -1338,7 +1338,8 @@
>  		INIT_DEFERRABLE_WORK(per_cpu_ptr(&vmstat_work, cpu),
>  			vmstat_update);
> 
> -	cpu_stat_off = kmalloc(cpumask_size(), GFP_KERNEL);
> +	if (!alloc_cpumask_var(&cpu_stat_off, GFP_KERNEL))
> +		BUG();

	BUG_ON(!alloc_cpumask_var(&cpu_stat_off, GFP_KERNEL));

>  	cpumask_copy(cpu_stat_off, cpu_online_mask);
> 
>  	schedule_delayed_work(&shepherd,
> --
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