[PATCH v2 01/25] mm: Add kfd_process pointer to mm_struct

[PATCH v2 01/25] mm: Add kfd_process pointer to mm_struct

[Oded Gabbay]

Forgot to add mm mailing list. Sorry.

This patch enables the amdkfd driver to retrieve the kfd_process
object from the process's mm_struct. This is needed because kfd_process
lifespan is bound to the process's mm_struct lifespan.

When amdkfd is notified about an mm_struct tear-down, it checks if the
kfd_process pointer is valid. If so, it releases the kfd_process object
and all relevant resources.

In v3 of the patchset I will update the binding to match the final discussions
on [PATCH 1/8] mmput: use notifier chain to call subsystem exit handler.
In the meantime, I'm going to try and see if I can drop the kfd_process
in mm_struct and remove the use of the new notification chain in mmput.
Instead, I will try to use the mmu release notifier.

Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>
---
  include/linux/mm_types.h | 14 ++++++++++++++
  1 file changed, 14 insertions(+)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 678097c..ff71496 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -20,6 +20,10 @@
  struct hmm;
  #endif
  +#if defined(CONFIG_HSA_RADEON) || defined(CONFIG_HSA_RADEON_MODULE)
+struct kfd_process;
+#endif
+
  #ifndef AT_VECTOR_SIZE_ARCH
  #define AT_VECTOR_SIZE_ARCH 0
  #endif
@@ -439,6 +443,16 @@ struct mm_struct {
  	 */
  	struct hmm *hmm;
  #endif
+#if defined(CONFIG_HSA_RADEON) || defined(CONFIG_HSA_RADEON_MODULE)
+	/*
+	 * kfd always register an mmu_notifier we rely on mmu notifier to keep
+	 * refcount on mm struct as well as forbiding registering kfd on a
+	 * dying mm
+	 *
+	 * This field is set with mmap_sem old in write mode.
+	 */
+	struct kfd_process *kfd_process;
+#endif
  #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
  	pgtable_t pmd_huge_pte; /* protected by page_table_lock */
  #endif
-- 
1.9.1

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Re: [PATCH v2 01/25] mm: Add kfd_process pointer to mm_struct

[Jerome Glisse]

On Thu, Jul 17, 2014 at 04:57:58PM +0300, Oded Gabbay wrote:
> Forgot to add mm mailing list. Sorry.
> 
> This patch enables the amdkfd driver to retrieve the kfd_process
> object from the process's mm_struct. This is needed because kfd_process
> lifespan is bound to the process's mm_struct lifespan.
> 
> When amdkfd is notified about an mm_struct tear-down, it checks if the
> kfd_process pointer is valid. If so, it releases the kfd_process object
> and all relevant resources.
> 
> In v3 of the patchset I will update the binding to match the final discussions
> on [PATCH 1/8] mmput: use notifier chain to call subsystem exit handler.
> In the meantime, I'm going to try and see if I can drop the kfd_process
> in mm_struct and remove the use of the new notification chain in mmput.
> Instead, I will try to use the mmu release notifier.

So the mmput notifier chain will not happen. I did a patch with call_srcu
and adding couple more helper to mmu_notifier. I will send that today for
review.

That being said, adding a device driver specific to mm_struct will most
likely be a big no. I am myself gonna remove hmm from mm_struct as people
are reluctant to see such change.

Cheers,
Jerome


> 
> Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>
> ---
>  include/linux/mm_types.h | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 678097c..ff71496 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -20,6 +20,10 @@
>  struct hmm;
>  #endif
>  +#if defined(CONFIG_HSA_RADEON) || defined(CONFIG_HSA_RADEON_MODULE)
> +struct kfd_process;
> +#endif
> +
>  #ifndef AT_VECTOR_SIZE_ARCH
>  #define AT_VECTOR_SIZE_ARCH 0
>  #endif
> @@ -439,6 +443,16 @@ struct mm_struct {
>  	 */
>  	struct hmm *hmm;
>  #endif
> +#if defined(CONFIG_HSA_RADEON) || defined(CONFIG_HSA_RADEON_MODULE)
> +	/*
> +	 * kfd always register an mmu_notifier we rely on mmu notifier to keep
> +	 * refcount on mm struct as well as forbiding registering kfd on a
> +	 * dying mm
> +	 *
> +	 * This field is set with mmap_sem old in write mode.
> +	 */
> +	struct kfd_process *kfd_process;
> +#endif
>  #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
>  	pgtable_t pmd_huge_pte; /* protected by page_table_lock */
>  #endif
> -- 
> 1.9.1
> 

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Re: [PATCH v2 01/25] mm: Add kfd_process pointer to mm_struct

[Oded Gabbay]

On 17/07/14 17:12, Jerome Glisse wrote:
> On Thu, Jul 17, 2014 at 04:57:58PM +0300, Oded Gabbay wrote:
>> Forgot to add mm mailing list. Sorry.
>>
>> This patch enables the amdkfd driver to retrieve the kfd_process
>> object from the process's mm_struct. This is needed because kfd_process
>> lifespan is bound to the process's mm_struct lifespan.
>>
>> When amdkfd is notified about an mm_struct tear-down, it checks if the
>> kfd_process pointer is valid. If so, it releases the kfd_process object
>> and all relevant resources.
>>
>> In v3 of the patchset I will update the binding to match the final discussions
>> on [PATCH 1/8] mmput: use notifier chain to call subsystem exit handler.
>> In the meantime, I'm going to try and see if I can drop the kfd_process
>> in mm_struct and remove the use of the new notification chain in mmput.
>> Instead, I will try to use the mmu release notifier.
>
> So the mmput notifier chain will not happen. I did a patch with call_srcu
> and adding couple more helper to mmu_notifier. I will send that today for
> review.
>
> That being said, adding a device driver specific to mm_struct will most
> likely be a big no. I am myself gonna remove hmm from mm_struct as people
> are reluctant to see such change.
>
> Cheers,
> Jérôme
>
Yes, I followed that email thread and you can see that in the commit message I 
referred to it (saying that in v3 of the patchset I'm also going to use 
mmu_notifier). I will take your patch once you publish it and use it to change 
amdkfd behavior.

	Oded
>
>>
>> Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>
>> ---
>>   include/linux/mm_types.h | 14 ++++++++++++++
>>   1 file changed, 14 insertions(+)
>>
>> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
>> index 678097c..ff71496 100644
>> --- a/include/linux/mm_types.h
>> +++ b/include/linux/mm_types.h
>> @@ -20,6 +20,10 @@
>>   struct hmm;
>>   #endif
>>   +#if defined(CONFIG_HSA_RADEON) || defined(CONFIG_HSA_RADEON_MODULE)
>> +struct kfd_process;
>> +#endif
>> +
>>   #ifndef AT_VECTOR_SIZE_ARCH
>>   #define AT_VECTOR_SIZE_ARCH 0
>>   #endif
>> @@ -439,6 +443,16 @@ struct mm_struct {
>>   	 */
>>   	struct hmm *hmm;
>>   #endif
>> +#if defined(CONFIG_HSA_RADEON) || defined(CONFIG_HSA_RADEON_MODULE)
>> +	/*
>> +	 * kfd always register an mmu_notifier we rely on mmu notifier to keep
>> +	 * refcount on mm struct as well as forbiding registering kfd on a
>> +	 * dying mm
>> +	 *
>> +	 * This field is set with mmap_sem old in write mode.
>> +	 */
>> +	struct kfd_process *kfd_process;
>> +#endif
>>   #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
>>   	pgtable_t pmd_huge_pte; /* protected by page_table_lock */
>>   #endif
>> --
>> 1.9.1
>>

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