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[PATCH] sched/core: Fix a missed update of user_cpus_ptr

Waiman Long posted 1 patch 2 years, 7 months ago
There is a newer version of this series
kernel/sched/core.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
[PATCH] sched/core: Fix a missed update of user_cpus_ptr
Posted by Waiman Long 2 years, 7 months ago 
Since commit 8f9ea86fdf99 ("sched: Always preserve the user requested
cpumask"), a successful call to sched_setaffinity() should always save
the user requested cpu affinity mask in a task's user_cpus_ptr. However,
when the given cpu mask is the same as the current one, user_cpus_ptr
is not updated. Fix this by saving the user mask in this case too.

Fixes: 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask")
Signed-off-by: Waiman Long <longman@redhat.com>
---
 kernel/sched/core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 30d9752e2ca5..91255f791df3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2951,8 +2951,11 @@ static int __set_cpus_allowed_ptr_locked(struct task_struct *p,
 	}
 
 	if (!(ctx->flags & SCA_MIGRATE_ENABLE)) {
-		if (cpumask_equal(&p->cpus_mask, ctx->new_mask))
+		if (cpumask_equal(&p->cpus_mask, ctx->new_mask)) {
+			if (ctx->flags & SCA_USER)
+				swap(p->user_cpus_ptr, ctx->user_mask);
 			goto out;
+		}
 
 		if (WARN_ON_ONCE(p == current &&
 				 is_migration_disabled(p) &&
-- 
2.31.1
Re: [PATCH] sched/core: Fix a missed update of user_cpus_ptr
Posted by Peter Zijlstra 2 years, 7 months ago 
On Fri, Feb 03, 2023 at 01:18:49PM -0500, Waiman Long wrote:
> Since commit 8f9ea86fdf99 ("sched: Always preserve the user requested
> cpumask"), a successful call to sched_setaffinity() should always save
> the user requested cpu affinity mask in a task's user_cpus_ptr. However,
> when the given cpu mask is the same as the current one, user_cpus_ptr
> is not updated. Fix this by saving the user mask in this case too.
> 
> Fixes: 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask")
> Signed-off-by: Waiman Long <longman@redhat.com>
> ---
>  kernel/sched/core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 30d9752e2ca5..91255f791df3 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -2951,8 +2951,11 @@ static int __set_cpus_allowed_ptr_locked(struct task_struct *p,
>  	}
>  
>  	if (!(ctx->flags & SCA_MIGRATE_ENABLE)) {
> -		if (cpumask_equal(&p->cpus_mask, ctx->new_mask))
> +		if (cpumask_equal(&p->cpus_mask, ctx->new_mask)) {
> +			if (ctx->flags & SCA_USER)
> +				swap(p->user_cpus_ptr, ctx->user_mask);
>  			goto out;
> +		}
>  
>  		if (WARN_ON_ONCE(p == current &&
>  				 is_migration_disabled(p) &&

Indeed. Thanks!
Re: [PATCH] sched/core: Fix a missed update of user_cpus_ptr
Posted by Tejun Heo 2 years, 7 months ago 
On Fri, Feb 03, 2023 at 01:18:49PM -0500, Waiman Long wrote:
> Since commit 8f9ea86fdf99 ("sched: Always preserve the user requested
> cpumask"), a successful call to sched_setaffinity() should always save
> the user requested cpu affinity mask in a task's user_cpus_ptr. However,
> when the given cpu mask is the same as the current one, user_cpus_ptr
> is not updated. Fix this by saving the user mask in this case too.
> 
> Fixes: 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask")
> Signed-off-by: Waiman Long <longman@redhat.com>
> ---
>  kernel/sched/core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 30d9752e2ca5..91255f791df3 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -2951,8 +2951,11 @@ static int __set_cpus_allowed_ptr_locked(struct task_struct *p,
>  	}
>  
>  	if (!(ctx->flags & SCA_MIGRATE_ENABLE)) {
> -		if (cpumask_equal(&p->cpus_mask, ctx->new_mask))
> +		if (cpumask_equal(&p->cpus_mask, ctx->new_mask)) {
> +			if (ctx->flags & SCA_USER)
> +				swap(p->user_cpus_ptr, ctx->user_mask);
>  			goto out;
> +		}
>  
>  		if (WARN_ON_ONCE(p == current &&
>  				 is_migration_disabled(p) &&

and this is for a separate bug and should go through the scheduler tree.

Thanks.

-- 
tejun
Re: [PATCH] sched/core: Fix a missed update of user_cpus_ptr
Posted by Waiman Long 2 years, 7 months ago 
On 2/3/23 16:04, Tejun Heo wrote:
> On Fri, Feb 03, 2023 at 01:18:49PM -0500, Waiman Long wrote:
>> Since commit 8f9ea86fdf99 ("sched: Always preserve the user requested
>> cpumask"), a successful call to sched_setaffinity() should always save
>> the user requested cpu affinity mask in a task's user_cpus_ptr. However,
>> when the given cpu mask is the same as the current one, user_cpus_ptr
>> is not updated. Fix this by saving the user mask in this case too.
>>
>> Fixes: 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask")
>> Signed-off-by: Waiman Long <longman@redhat.com>
>> ---
>>   kernel/sched/core.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index 30d9752e2ca5..91255f791df3 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -2951,8 +2951,11 @@ static int __set_cpus_allowed_ptr_locked(struct task_struct *p,
>>   	}
>>   
>>   	if (!(ctx->flags & SCA_MIGRATE_ENABLE)) {
>> -		if (cpumask_equal(&p->cpus_mask, ctx->new_mask))
>> +		if (cpumask_equal(&p->cpus_mask, ctx->new_mask)) {
>> +			if (ctx->flags & SCA_USER)
>> +				swap(p->user_cpus_ptr, ctx->user_mask);
>>   			goto out;
>> +		}
>>   
>>   		if (WARN_ON_ONCE(p == current &&
>>   				 is_migration_disabled(p) &&
> and this is for a separate bug and should go through the scheduler tree.

Yes, this is for Peter to pick up.

Cheers,
Longman
[tip: sched/urgent] sched/core: Fix a missed update of user_cpus_ptr
Posted by tip-bot2 for Waiman Long 2 years, 6 months ago 
The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     df14b7f9efcda35e59bb6f50351aac25c50f6e24
Gitweb:        https://git.kernel.org/tip/df14b7f9efcda35e59bb6f50351aac25c50f6e24
Author:        Waiman Long <longman@redhat.com>
AuthorDate:    Fri, 03 Feb 2023 13:18:49 -05:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 13 Feb 2023 16:36:14 +01:00

sched/core: Fix a missed update of user_cpus_ptr

Since commit 8f9ea86fdf99 ("sched: Always preserve the user requested
cpumask"), a successful call to sched_setaffinity() should always save
the user requested cpu affinity mask in a task's user_cpus_ptr. However,
when the given cpu mask is the same as the current one, user_cpus_ptr
is not updated. Fix this by saving the user mask in this case too.

Fixes: 8f9ea86fdf99 ("sched: Always preserve the user requested cpumask")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230203181849.221943-1-longman@redhat.com
---
 kernel/sched/core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e838feb..2a4918a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2951,8 +2951,11 @@ static int __set_cpus_allowed_ptr_locked(struct task_struct *p,
 	}
 
 	if (!(ctx->flags & SCA_MIGRATE_ENABLE)) {
-		if (cpumask_equal(&p->cpus_mask, ctx->new_mask))
+		if (cpumask_equal(&p->cpus_mask, ctx->new_mask)) {
+			if (ctx->flags & SCA_USER)
+				swap(p->user_cpus_ptr, ctx->user_mask);
 			goto out;
+		}
 
 		if (WARN_ON_ONCE(p == current &&
 				 is_migration_disabled(p) &&

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