[PATCH 0/3] sched: Sched Domains: Fixups - Part 3

[PATCH 0/3] sched: Sched Domains: Fixups - Part 3

[Viresh Kumar]

Hi Peter/Ingo,

This set contains few more minor fixes that I could find for code responsible
for creating sched domains. They are rebased of my earlier fixes:

Part 1:
https://lkml.org/lkml/2013/6/4/253

Part 2:
https://lkml.org/lkml/2013/6/10/141

They should be applied in this order to avoid conflicts.

My study of "How scheduling domains are created" is almost over now and so
probably this is my last patchset for fixes related to scheduling domains.

Sorry for three separate sets, I sent them as soon as I had few of them sitting
in my tree.

Viresh Kumar (3):
  sched: Use cached value of span instead of calling
    sched_domain_span()
  sched: don't call get_group() for covered cpus
  sched: remove WARN_ON(!sd) from init_sched_groups_power()

 kernel/sched/core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

-- 
1.7.12.rc2.18.g61b472e

[PATCH 1/3] sched: Use cached value of span instead of calling sched_domain_span()

[Viresh Kumar]

In the beginning of build_sched_groups() we called sched_domain_span() and
cached its return value in span. Few statements later we are calling it again to
get the same pointer.

Lets use the cached value instead as it hasn't changed in between.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 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 e585e10..4abc743 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5334,7 +5334,7 @@ build_sched_groups(struct sched_domain *sd, int cpu)
 	get_group(cpu, sdd, &sd->groups);
 	atomic_inc(&sd->groups->ref);
 
-	if (cpu != cpumask_first(sched_domain_span(sd)))
+	if (cpu != cpumask_first(span))
 		return 0;
 
 	lockdep_assert_held(&sched_domains_mutex);
-- 
1.7.12.rc2.18.g61b472e

[tip:sched/core] sched: Use cached value of span instead of calling sched_domain_span()

[tip-bot for Viresh Kumar]

Commit-ID:  0936629f01bb1b11772db8c36be421365238cbec
Gitweb:     http://git.kernel.org/tip/0936629f01bb1b11772db8c36be421365238cbec
Author:     Viresh Kumar <viresh.kumar@linaro.org>
AuthorDate: Tue, 11 Jun 2013 16:32:43 +0530
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 19 Jun 2013 12:58:46 +0200

sched: Use cached value of span instead of calling sched_domain_span()

In the beginning of build_sched_groups() we called sched_domain_span() and
cached its return value in span. Few statements later we are calling it again to
get the same pointer.

Lets use the cached value instead as it hasn't changed in between.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/834ecd507071ad88aff039352dbc7e063dd996a7.1370948150.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 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 547b7d3..3388387 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5347,7 +5347,7 @@ build_sched_groups(struct sched_domain *sd, int cpu)
 	get_group(cpu, sdd, &sd->groups);
 	atomic_inc(&sd->groups->ref);
 
-	if (cpu != cpumask_first(sched_domain_span(sd)))
+	if (cpu != cpumask_first(span))
 		return 0;
 
 	lockdep_assert_held(&sched_domains_mutex);

[PATCH 2/3] sched: don't call get_group() for covered cpus

[Viresh Kumar]

In build_sched_groups() we don't need to call get_group() for cpus which are
already covered in previous iterations. So, call get_group() after checking if
cpu is covered or not.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 kernel/sched/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4abc743..27842f5 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5344,12 +5344,12 @@ build_sched_groups(struct sched_domain *sd, int cpu)
 
 	for_each_cpu(i, span) {
 		struct sched_group *sg;
-		int group = get_group(i, sdd, &sg);
-		int j;
+		int group, j;
 
 		if (cpumask_test_cpu(i, covered))
 			continue;
 
+		group = get_group(i, sdd, &sg);
 		cpumask_clear(sched_group_cpus(sg));
 		sg->sgp->power = 0;
 		cpumask_setall(sched_group_mask(sg));
-- 
1.7.12.rc2.18.g61b472e

Re: [PATCH 2/3] sched: don't call get_group() for covered cpus

[Peter Zijlstra]

On Tue, Jun 11, 2013 at 04:32:44PM +0530, Viresh Kumar wrote:
> In build_sched_groups() we don't need to call get_group() for cpus which are
> already covered in previous iterations. So, call get_group() after checking if
> cpu is covered or not.
> 

Aside from not needing it; doing it would mark the group used and
eventually leak it since we wouldn't connect it and not find it again to
free it, right?

So effectively this fixes a memory leak?

> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
>  kernel/sched/core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 4abc743..27842f5 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5344,12 +5344,12 @@ build_sched_groups(struct sched_domain *sd, int cpu)
>  
>  	for_each_cpu(i, span) {
>  		struct sched_group *sg;
> -		int group = get_group(i, sdd, &sg);
> -		int j;
> +		int group, j;
>  
>  		if (cpumask_test_cpu(i, covered))
>  			continue;
>  
> +		group = get_group(i, sdd, &sg);
>  		cpumask_clear(sched_group_cpus(sg));
>  		sg->sgp->power = 0;
>  		cpumask_setall(sched_group_mask(sg));
> -- 
> 1.7.12.rc2.18.g61b472e
> 

Re: [PATCH 2/3] sched: don't call get_group() for covered cpus

[Viresh Kumar]

On 18 June 2013 15:33, Peter Zijlstra <peterz@infradead.org> wrote:
> On Tue, Jun 11, 2013 at 04:32:44PM +0530, Viresh Kumar wrote:
>> In build_sched_groups() we don't need to call get_group() for cpus which are
>> already covered in previous iterations. So, call get_group() after checking if
>> cpu is covered or not.
>>
>
> Aside from not needing it; doing it would mark the group used and
> eventually leak it since we wouldn't connect it and not find it again to
> free it, right?
>
> So effectively this fixes a memory leak?

Exactly. To be precise: In cases where sg->cpumask contained more
than one cpu (For any topology level), this patch helps freeing sg's
memory for all cpus leaving the group leader.

May I update the logs again?

Re: [PATCH 2/3] sched: don't call get_group() for covered cpus

[Peter Zijlstra]

On Tue, Jun 18, 2013 at 03:45:15PM +0530, Viresh Kumar wrote:
> On 18 June 2013 15:33, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Tue, Jun 11, 2013 at 04:32:44PM +0530, Viresh Kumar wrote:
> >> In build_sched_groups() we don't need to call get_group() for cpus which are
> >> already covered in previous iterations. So, call get_group() after checking if
> >> cpu is covered or not.
> >>
> >
> > Aside from not needing it; doing it would mark the group used and
> > eventually leak it since we wouldn't connect it and not find it again to
> > free it, right?
> >
> > So effectively this fixes a memory leak?
> 
> Exactly. To be precise: In cases where sg->cpumask contained more
> than one cpu (For any topology level), this patch helps freeing sg's
> memory for all cpus leaving the group leader.
> 
> May I update the logs again?

Sure. Just send a new patch and I'll substitute.

Re: [PATCH 2/3] sched: don't call get_group() for covered cpus

[Viresh Kumar]

[-- Attachment #1: Type: text/plain, Size: 812 bytes --]

On 18 June 2013 20:49, Peter Zijlstra <peterz@infradead.org> wrote:
> Sure. Just send a new patch and I'll substitute.

This is the new log (patch is attached):

sched: Fix memory leakage in build_sched_groups()

In build_sched_groups() we don't need to call get_group() for cpus which are
already covered in previous iterations. Calling get_group() would mark the group
used and eventually leak it since we wouldn't connect it and not find it again
to free it.

This will happen only in cases where sg->cpumask contained more than one cpu
(For any topology level). This patch would free sg's memory for all cpus leaving
the group leader as the group isn't marked used now.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 kernel/sched/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

[-- Attachment #2: 0001-sched-Fix-memory-leakage-in-build_sched_groups.patch --]
[-- Type: application/octet-stream, Size: 1473 bytes --]

From fa73208bbfa0c16e4677695073632edb9662343e Mon Sep 17 00:00:00 2001
Message-Id: <fa73208bbfa0c16e4677695073632edb9662343e.1371569345.git.viresh.kumar@linaro.org>
From: Viresh Kumar <viresh.kumar@linaro.org>
Date: Tue, 11 Jun 2013 14:43:43 +0530
Subject: [PATCH] sched: Fix memory leakage in build_sched_groups()

In build_sched_groups() we don't need to call get_group() for cpus which are
already covered in previous iterations. Calling get_group() would mark the group
used and eventually leak it since we wouldn't connect it and not find it again
to free it.

This will happen only in cases where sg->cpumask contained more than one cpu
(For any topology level). This patch would free sg's memory for all cpus leaving
the group leader as the group isn't marked used now.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 kernel/sched/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4abc743..27842f5 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5344,12 +5344,12 @@ build_sched_groups(struct sched_domain *sd, int cpu)
 
 	for_each_cpu(i, span) {
 		struct sched_group *sg;
-		int group = get_group(i, sdd, &sg);
-		int j;
+		int group, j;
 
 		if (cpumask_test_cpu(i, covered))
 			continue;
 
+		group = get_group(i, sdd, &sg);
 		cpumask_clear(sched_group_cpus(sg));
 		sg->sgp->power = 0;
 		cpumask_setall(sched_group_mask(sg));
-- 
1.7.12.rc2.18.g61b472e

Re: [PATCH 2/3] sched: don't call get_group() for covered cpus

[Peter Zijlstra]

On Tue, Jun 18, 2013 at 08:59:39PM +0530, Viresh Kumar wrote:
> On 18 June 2013 20:49, Peter Zijlstra <peterz@infradead.org> wrote:
> > Sure. Just send a new patch and I'll substitute.
> 
> This is the new log (patch is attached):
> 
> sched: Fix memory leakage in build_sched_groups()
> 
> In build_sched_groups() we don't need to call get_group() for cpus which are
> already covered in previous iterations. Calling get_group() would mark the group
> used and eventually leak it since we wouldn't connect it and not find it again
> to free it.
> 
> This will happen only in cases where sg->cpumask contained more than one cpu
> (For any topology level). This patch would free sg's memory for all cpus leaving
> the group leader as the group isn't marked used now.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Thanks!

[tip:sched/core] sched: Fix memory leakage in build_sched_groups( )

[tip-bot for Viresh Kumar]

Commit-ID:  cd08e9234c987766ad077bba80eb5a07d0855525
Gitweb:     http://git.kernel.org/tip/cd08e9234c987766ad077bba80eb5a07d0855525
Author:     Viresh Kumar <viresh.kumar@linaro.org>
AuthorDate: Tue, 11 Jun 2013 16:32:44 +0530
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 19 Jun 2013 12:58:46 +0200

sched: Fix memory leakage in build_sched_groups()

In build_sched_groups() we don't need to call get_group() for cpus
which are already covered in previous iterations. Calling get_group()
would mark the group used and eventually leak it since we wouldn't
connect it and not find it again to free it.

This will happen only in cases where sg->cpumask contained more than
one cpu (For any topology level). This patch would free sg's memory
for all cpus leaving the group leader as the group isn't marked used
now.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/7a61e955abdcbb1dfa9fe493f11a5ec53a11ddd3.1370948150.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3388387..014c97f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5357,12 +5357,12 @@ build_sched_groups(struct sched_domain *sd, int cpu)
 
 	for_each_cpu(i, span) {
 		struct sched_group *sg;
-		int group = get_group(i, sdd, &sg);
-		int j;
+		int group, j;
 
 		if (cpumask_test_cpu(i, covered))
 			continue;
 
+		group = get_group(i, sdd, &sg);
 		cpumask_clear(sched_group_cpus(sg));
 		sg->sgp->power = 0;
 		cpumask_setall(sched_group_mask(sg));

[PATCH 3/3] sched: remove WARN_ON(!sd) from init_sched_groups_power()

[Viresh Kumar]

sd can't be NULL in init_sched_groups_power() and so checking it for NULL isn't
useful. In case it is required, then also we need to rearrange the code a bit as
we already accessed invalid pointer sd to get sg: sg = sd->groups.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 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 27842f5..c949f6d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5387,7 +5387,7 @@ static void init_sched_groups_power(int cpu, struct sched_domain *sd)
 {
 	struct sched_group *sg = sd->groups;
 
-	WARN_ON(!sd || !sg);
+	WARN_ON(!sg);
 
 	do {
 		sg->group_weight = cpumask_weight(sched_group_cpus(sg));
-- 
1.7.12.rc2.18.g61b472e

Re: [PATCH 3/3] sched: remove WARN_ON(!sd) from init_sched_groups_power()

[Peter Zijlstra]

On Tue, Jun 11, 2013 at 04:32:45PM +0530, Viresh Kumar wrote:
> sd can't be NULL in init_sched_groups_power() and so checking it for NULL isn't
> useful. In case it is required, then also we need to rearrange the code a bit as
> we already accessed invalid pointer sd to get sg: sg = sd->groups.
> 

Err on the side of paranoia :-)

[tip:sched/core] sched: Remove WARN_ON(!sd) from init_sched_groups_power()

[tip-bot for Viresh Kumar]

Commit-ID:  94c95ba69f31e435416988ddb223c92e5b0e9e83
Gitweb:     http://git.kernel.org/tip/94c95ba69f31e435416988ddb223c92e5b0e9e83
Author:     Viresh Kumar <viresh.kumar@linaro.org>
AuthorDate: Tue, 11 Jun 2013 16:32:45 +0530
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 19 Jun 2013 12:58:47 +0200

sched: Remove WARN_ON(!sd) from init_sched_groups_power()

sd can't be NULL in init_sched_groups_power() and so checking it for NULL isn't
useful. In case it is required, then also we need to rearrange the code a bit as
we already accessed invalid pointer sd to get sg: sg = sd->groups.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/2bbe633cd74b431c05253a8ce61fdfd5066a531b.1370948150.git.viresh.kumar@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 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 014c97f..21b1403 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5400,7 +5400,7 @@ static void init_sched_groups_power(int cpu, struct sched_domain *sd)
 {
 	struct sched_group *sg = sd->groups;
 
-	WARN_ON(!sd || !sg);
+	WARN_ON(!sg);
 
 	do {
 		sg->group_weight = cpumask_weight(sched_group_cpus(sg));