linux-kernel - [PATCH 1/1] sched: remove unnecessary kzalloc in sched_init

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Date:	Tue, 22 Apr 2008 10:04:26 -0700
From:	Mike Travis <travis@....com>
To:	Tony Luck <tony.luck@...el.com>, Ingo Molnar <mingo@...e.hu>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/1] sched: remove unnecessary kzalloc in sched_init_smp

Tony Luck wrote:
> On Fri, Apr 4, 2008 at 6:11 PM, Mike Travis <travis@....com> wrote:
>>  @@ -7297,6 +7287,11 @@ void __init sched_init_smp(void)
>>   #else
>>   void __init sched_init_smp(void)
>>   {
>>  +#if defined(CONFIG_NUMA)
>>  +       sched_group_nodes_bycpu = kzalloc(nr_cpu_ids * sizeof(void **),
>>  +                                                               GFP_KERNEL);
>>  +       BUG_ON(sched_group_nodes_bycpu == NULL);
>>  +#endif
>>         sched_init_granularity();
>>   }
>>   #endif /* CONFIG_SMP */
> 
> This hunk is causing problems with one of my builds (generic,
> uniprocessor). Note
> that the #else at the start of this hunk is from a #ifdef CONFIG_SMP ... so I'm
> wondering why we need #if defined(CONFIG_NUMA) inside uniprocessor code :-)
> How can you have NUMA issues with only one cpu!!!

>>> CONFIG_NUMA is dependent on CONFIG_SMP for x86 so that caused me to miss
>>> the error.  But here's the fix:

  * sched_group_nodes_bycpu is defined only for the SMP + NUMA case,
    it should not be referenced in the !SMP + NUMA case.

For inclusion into sched-devel/latest tree.

Based on:
	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
    +   sched-devel/latest  .../mingo/linux-2.6-sched-devel.git

Signed-off-by: Mike Travis <travis@....com>
---
 kernel/sched.c |    5 -----
 1 file changed, 5 deletions(-)

--- linux-2.6.sched.orig/kernel/sched.c
+++ linux-2.6.sched/kernel/sched.c
@@ -8028,11 +8028,6 @@ void __init sched_init_smp(void)
 #else
 void __init sched_init_smp(void)
 {
-#if defined(CONFIG_NUMA)
-	sched_group_nodes_bycpu = kzalloc(nr_cpu_ids * sizeof(void **),
-								GFP_KERNEL);
-	BUG_ON(sched_group_nodes_bycpu == NULL);
-#endif
 	sched_init_granularity();
 }
 #endif /* CONFIG_SMP */
--
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