linux-kernel - Re: [PATCH] x86, numa: exit early on numa_reset

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Message-ID: <4D5C5909.4020405@kernel.org>
Date:	Wed, 16 Feb 2011 15:08:57 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Tejun Heo <tj@...nel.org>
CC:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>,
	David Rientjes <rientjes@...gle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86, numa: exit early on numa_reset_distance()

On 02/16/2011 02:39 PM, Tejun Heo wrote:
> On Wed, Feb 16, 2011 at 12:56:47PM -0800, Yinghai Lu wrote:
>>
>> Do not call __pa(numa_distance), if it is not allocated before.
>>
>> it will get BUG_ON if VIRTUAL_DEBUG is on.
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> 
> Thanks for spotting this.
> 
>> Index: linux-2.6/arch/x86/mm/numa_64.c
>> ===================================================================
>> --- linux-2.6.orig/arch/x86/mm/numa_64.c
>> +++ linux-2.6/arch/x86/mm/numa_64.c
>> @@ -371,6 +371,12 @@ static void __init numa_reset_distance(v
>>  {
>>  	size_t size;
>>  
>> +	if (!numa_distance_cnt) {
>> +		numa_distance = NULL;
>> +
>> +		return;
>> +	}
>> +
> 
> But please move the existing numa_distance = NULL before the
> conditional and do if (!numa_distance_cnt) return;

confused. Do you mean this one ?

[PATCH -v2] x86, numa: exit early on numa_reset_distance()

Do not call __pa(numa_distance), if it is not allocated before.

it will get BUG_ON if VIRTUAL_DEBUG is on.

-v2: change to check existing path as tj requested.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>

---
 arch/x86/mm/numa_64.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Index: linux-2.6/arch/x86/mm/numa_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/numa_64.c
+++ linux-2.6/arch/x86/mm/numa_64.c
@@ -371,11 +371,13 @@ static void __init numa_reset_distance(v
 {
 	size_t size;
 
-	size = numa_distance_cnt * sizeof(numa_distance[0]);
-	memblock_x86_free_range(__pa(numa_distance),
-				__pa(numa_distance) + size);
+	if (numa_distance_cnt) {
+		size = numa_distance_cnt * sizeof(numa_distance[0]);
+		memblock_x86_free_range(__pa(numa_distance),
+					__pa(numa_distance) + size);
+		numa_distance_cnt = 0;
+	}
 	numa_distance = NULL;
-	numa_distance_cnt = 0;
 }
 
 /*

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