sched: fix: initialization of sched_domain_topology for NUMA

sched: fix: initialization of sched_domain_topology for NUMA

[Vincent Guittot]

sched_domain_topology table is a null terminated array. 
Add 1 row in the allocation size that will be used as the last row of the
table.

Reported-by: Jet Chen <jet.chen@intel.com>
Tested-by: Jet Chen <jet.chen@intel.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
link: https://lkml.org/lkml/2014/5/12/130

---

Hi Ingo and Peter,

This patch fixes the problem that has been reported by Jet Chen 

Regards,
Vincent

 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4ea7b3f..205fa17 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6234,7 +6234,7 @@ static void sched_init_numa(void)
 	/* Compute default topology size */
 	for (i = 0; sched_domain_topology[i].mask; i++);
 
-	tl = kzalloc((i + level) *
+	tl = kzalloc((i + level + 1) *
 			sizeof(struct sched_domain_topology_level), GFP_KERNEL);
 	if (!tl)
 		return;
-- 
1.9.1

Re: sched: fix: initialization of sched_domain_topology for NUMA

[Peter Zijlstra]

On Mon, May 12, 2014 at 11:16:16PM +0200, Vincent Guittot wrote:
> sched_domain_topology table is a null terminated array. 
> Add 1 row in the allocation size that will be used as the last row of the
> table.
> 
> Reported-by: Jet Chen <jet.chen@intel.com>
> Tested-by: Jet Chen <jet.chen@intel.com>
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
> link: https://lkml.org/lkml/2014/5/12/130
> 
> ---
> 
> Hi Ingo and Peter,
> 
> This patch fixes the problem that has been reported by Jet Chen 
> 

I have no mail from Jet Chen on any recent issues.

Also, please describe both the problem and the fix in the Changelog
without need to refer to secondary sources.

As it stands I've no clue wth this is about.

Re: sched: fix: initialization of sched_domain_topology for NUMA

[Vincent Guittot]

On 13 May 2014 10:26, Peter Zijlstra <peterz@infradead.org> wrote:
> On Mon, May 12, 2014 at 11:16:16PM +0200, Vincent Guittot wrote:
>> sched_domain_topology table is a null terminated array.
>> Add 1 row in the allocation size that will be used as the last row of the
>> table.
>>
>> Reported-by: Jet Chen <jet.chen@intel.com>
>> Tested-by: Jet Chen <jet.chen@intel.com>
>> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
>> link: https://lkml.org/lkml/2014/5/12/130
>>
>> ---
>>
>> Hi Ingo and Peter,
>>
>> This patch fixes the problem that has been reported by Jet Chen
>>
>
> I have no mail from Jet Chen on any recent issues.

Hi Peter,

I have just noticed that you were not in the list of the original message

>
> Also, please describe both the problem and the fix in the Changelog
> without need to refer to secondary sources.

Ok, i'm going to update the commit message with more information

>
> As it stands I've no clue wth this is about.

sched: fix: initialization of sched_domain_topology for NUMA

[Vincent Guittot]

Jet Chen has reported a kernel panics when booting qemu-system-x86_64 with
kvm64 cpu. A panic occured while building the sched_domain.

In sched_init_numa, we create a new topology table in which both default
levels and numa levels are copied. The last row of the table must have a null
pointer in the mask field.

The current implementation doesn't add this last row in the computation of the
table size. So we add 1 row in the allocation size that will be used as the
last row of the table. The kzalloc will ensure that the mask field is NULL.

Reported-by: Jet Chen <jet.chen@intel.com>
Tested-by: Jet Chen <jet.chen@intel.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
link: https://lkml.org/lkml/2014/5/12/130

---

Hi Peter,

Does this commit message contain enough information ?

Regards,
Vincent

 kernel/sched/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4ea7b3f..205fa17 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6234,7 +6234,7 @@ static void sched_init_numa(void)
 	/* Compute default topology size */
 	for (i = 0; sched_domain_topology[i].mask; i++);
 
-	tl = kzalloc((i + level) *
+	tl = kzalloc((i + level + 1) *
 			sizeof(struct sched_domain_topology_level), GFP_KERNEL);
 	if (!tl)
 		return;
-- 
1.9.1

Re: sched: fix: initialization of sched_domain_topology for NUMA

[Peter Zijlstra]

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On Tue, May 13, 2014 at 11:11:01AM +0200, Vincent Guittot wrote:
> Jet Chen has reported a kernel panics when booting qemu-system-x86_64 with
> kvm64 cpu. A panic occured while building the sched_domain.
> 
> In sched_init_numa, we create a new topology table in which both default
> levels and numa levels are copied. The last row of the table must have a null
> pointer in the mask field.
> 
> The current implementation doesn't add this last row in the computation of the
> table size. So we add 1 row in the allocation size that will be used as the
> last row of the table. The kzalloc will ensure that the mask field is NULL.
> 
> Reported-by: Jet Chen <jet.chen@intel.com>
> Tested-by: Jet Chen <jet.chen@intel.com>
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
> link: https://lkml.org/lkml/2014/5/12/130
> 
> ---
> 
> Hi Peter,
> 
> Does this commit message contain enough information ?

Yes, thanks!

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