[v6] cpuset/isolation: Honour kthreads preferred affinity

[PATCH 12/33] cpuset: Provide lockdep check for cpuset lock held

Posted by Frederic Weisbecker 1 month, 1 week ago

cpuset modifies partitions, including isolated, while holding the cpuset
mutex.

This means that holding the cpuset mutex is safe to synchronize against
housekeeping cpumask changes.

Provide a lockdep check to validate that.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 include/linux/cpuset.h | 2 ++
 kernel/cgroup/cpuset.c | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index a98d3330385c..1c49ffd2ca9b 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -18,6 +18,8 @@
 #include <linux/mmu_context.h>
 #include <linux/jump_label.h>
 
+extern bool lockdep_is_cpuset_held(void);
+
 #ifdef CONFIG_CPUSETS
 
 /*
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 3afa72f8d579..5e2e3514c22e 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -283,6 +283,13 @@ void cpuset_full_unlock(void)
 	cpus_read_unlock();
 }
 
+#ifdef CONFIG_LOCKDEP
+bool lockdep_is_cpuset_held(void)
+{
+	return lockdep_is_held(&cpuset_mutex);
+}
+#endif
+
 static DEFINE_SPINLOCK(callback_lock);
 
 void cpuset_callback_lock_irq(void)
-- 
2.51.1

Re: [PATCH 12/33] cpuset: Provide lockdep check for cpuset lock held

Posted by Waiman Long 4 weeks ago

On 1/1/26 5:13 PM, Frederic Weisbecker wrote:
> cpuset modifies partitions, including isolated, while holding the cpuset
> mutex.
>
> This means that holding the cpuset mutex is safe to synchronize against
> housekeeping cpumask changes.
>
> Provide a lockdep check to validate that.
>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> ---
>   include/linux/cpuset.h | 2 ++
>   kernel/cgroup/cpuset.c | 7 +++++++
>   2 files changed, 9 insertions(+)
>
> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
> index a98d3330385c..1c49ffd2ca9b 100644
> --- a/include/linux/cpuset.h
> +++ b/include/linux/cpuset.h
> @@ -18,6 +18,8 @@
>   #include <linux/mmu_context.h>
>   #include <linux/jump_label.h>
>   
> +extern bool lockdep_is_cpuset_held(void);
> +
>   #ifdef CONFIG_CPUSETS
>   
>   /*
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 3afa72f8d579..5e2e3514c22e 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -283,6 +283,13 @@ void cpuset_full_unlock(void)
>   	cpus_read_unlock();
>   }
>   
> +#ifdef CONFIG_LOCKDEP
> +bool lockdep_is_cpuset_held(void)
> +{
> +	return lockdep_is_held(&cpuset_mutex);
> +}
> +#endif
> +
>   static DEFINE_SPINLOCK(callback_lock);
>   
>   void cpuset_callback_lock_irq(void)

The cgroup/for-next tree already have a similar 
lockdep_assert_cpuset_lock_held() defined. So you can drop this patch if 
this series won't land in the next merge window.

Cheers,
Longman

Re: [PATCH 12/33] cpuset: Provide lockdep check for cpuset lock held

Posted by Waiman Long 3 weeks, 6 days ago

On 1/11/26 8:43 PM, Waiman Long wrote:
> On 1/1/26 5:13 PM, Frederic Weisbecker wrote:
>> cpuset modifies partitions, including isolated, while holding the cpuset
>> mutex.
>>
>> This means that holding the cpuset mutex is safe to synchronize against
>> housekeeping cpumask changes.
>>
>> Provide a lockdep check to validate that.
>>
>> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
>> ---
>>   include/linux/cpuset.h | 2 ++
>>   kernel/cgroup/cpuset.c | 7 +++++++
>>   2 files changed, 9 insertions(+)
>>
>> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
>> index a98d3330385c..1c49ffd2ca9b 100644
>> --- a/include/linux/cpuset.h
>> +++ b/include/linux/cpuset.h
>> @@ -18,6 +18,8 @@
>>   #include <linux/mmu_context.h>
>>   #include <linux/jump_label.h>
>>   +extern bool lockdep_is_cpuset_held(void);
>> +
>>   #ifdef CONFIG_CPUSETS
>>     /*
>> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
>> index 3afa72f8d579..5e2e3514c22e 100644
>> --- a/kernel/cgroup/cpuset.c
>> +++ b/kernel/cgroup/cpuset.c
>> @@ -283,6 +283,13 @@ void cpuset_full_unlock(void)
>>       cpus_read_unlock();
>>   }
>>   +#ifdef CONFIG_LOCKDEP
>> +bool lockdep_is_cpuset_held(void)
>> +{
>> +    return lockdep_is_held(&cpuset_mutex);
>> +}
>> +#endif
>> +
>>   static DEFINE_SPINLOCK(callback_lock);
>>     void cpuset_callback_lock_irq(void)
>
> The cgroup/for-next tree already have a similar 
> lockdep_assert_cpuset_lock_held() defined. So you can drop this patch 
> if this series won't land in the next merge window. 

Sorry, the other new lockdep API isn't exactly the same as what you 
propose here. So it is not a replacement for your use case. Sorry for 
the noise.

Cheers,
Longman