On 10/18/25 00:22, Felix Kuehling wrote:
>
> On 2025-10-13 09:48, Christian König wrote:
>> This should allow amdkfd_fences to outlive the amdgpu module.
>>
>> Signed-off-by: Christian König <[email protected]>
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 6 ++++
>> .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c | 36 +++++++------------
>> drivers/gpu/drm/amd/amdkfd/kfd_process.c | 7 ++--
>> drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 4 +--
>> 4 files changed, 24 insertions(+), 29 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>> index 9e120c934cc1..35c59c784b7b 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>> @@ -196,6 +196,7 @@ int kfd_debugfs_kfd_mem_limits(struct seq_file *m, void
>> *data);
>> #endif
>> #if IS_ENABLED(CONFIG_HSA_AMD)
>> bool amdkfd_fence_check_mm(struct dma_fence *f, struct mm_struct *mm);
>> +void amdkfd_fence_signal(struct dma_fence *f);
>> struct amdgpu_amdkfd_fence *to_amdgpu_amdkfd_fence(struct dma_fence *f);
>> void amdgpu_amdkfd_remove_all_eviction_fences(struct amdgpu_bo *bo);
>> int amdgpu_amdkfd_evict_userptr(struct mmu_interval_notifier *mni,
>> @@ -210,6 +211,11 @@ bool amdkfd_fence_check_mm(struct dma_fence *f, struct
>> mm_struct *mm)
>> return false;
>> }
>> +static inline
>> +void amdkfd_fence_signal(struct dma_fence *f)
>> +{
>> +}
>> +
>> static inline
>> struct amdgpu_amdkfd_fence *to_amdgpu_amdkfd_fence(struct dma_fence *f)
>> {
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
>> index 09c919f72b6c..69bca4536326 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
>> @@ -127,29 +127,9 @@ static bool amdkfd_fence_enable_signaling(struct
>> dma_fence *f)
>> if (!svm_range_schedule_evict_svm_bo(fence))
>> return true;
>> }
>> - return false;
>> -}
>> -
>> -/**
>> - * amdkfd_fence_release - callback that fence can be freed
>> - *
>> - * @f: dma_fence
>> - *
>> - * This function is called when the reference count becomes zero.
>> - * Drops the mm_struct reference and RCU schedules freeing up the fence.
>> - */
>> -static void amdkfd_fence_release(struct dma_fence *f)
>> -{
>> - struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
>> -
>> - /* Unconditionally signal the fence. The process is getting
>> - * terminated.
>> - */
>> - if (WARN_ON(!fence))
>> - return; /* Not an amdgpu_amdkfd_fence */
>> -
>> mmdrop(fence->mm);
>> - kfree_rcu(f, rcu);
>> + fence->mm = NULL;
>> + return false;
>> }
>> /**
>> @@ -174,9 +154,19 @@ bool amdkfd_fence_check_mm(struct dma_fence *f, struct
>> mm_struct *mm)
>> return false;
>> }
>> +void amdkfd_fence_signal(struct dma_fence *f)
>> +{
>> + struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
>> +
>> + if (fence) {
>> + mmdrop(fence->mm);
>> + fence->mm = NULL;
>
> Isn't fence->mm already NULL here if it was dropped in
> amdkfd_fence_enable_signaling?
It looked like ther're some use cases which signals the fence without going
through amdkfd_fence_enable_signaling.
E.g. kfd_process_wq_release which is most likely used on process tear down.
Regards,
Christian.
>
> Regards,
> Felix
>
>
>> + }
>> + dma_fence_signal(f);
>> +}
>> +
>> static const struct dma_fence_ops amdkfd_fence_ops = {
>> .get_driver_name = amdkfd_fence_get_driver_name,
>> .get_timeline_name = amdkfd_fence_get_timeline_name,
>> .enable_signaling = amdkfd_fence_enable_signaling,
>> - .release = amdkfd_fence_release,
>> };
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
>> b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
>> index ddfe30c13e9d..779d7701bac9 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
>> @@ -1177,7 +1177,7 @@ static void kfd_process_wq_release(struct work_struct
>> *work)
>> synchronize_rcu();
>> ef = rcu_access_pointer(p->ef);
>> if (ef)
>> - dma_fence_signal(ef);
>> + amdkfd_fence_signal(ef);
>> kfd_process_remove_sysfs(p);
>> kfd_debugfs_remove_process(p);
>> @@ -1986,7 +1986,6 @@ kfd_process_gpuid_from_node(struct kfd_process *p,
>> struct kfd_node *node,
>> static int signal_eviction_fence(struct kfd_process *p)
>> {
>> struct dma_fence *ef;
>> - int ret;
>> rcu_read_lock();
>> ef = dma_fence_get_rcu_safe(&p->ef);
>> @@ -1994,10 +1993,10 @@ static int signal_eviction_fence(struct kfd_process
>> *p)
>> if (!ef)
>> return -EINVAL;
>> - ret = dma_fence_signal(ef);
>> + amdkfd_fence_signal(ef);
>> dma_fence_put(ef);
>> - return ret;
>> + return 0;
>> }
>> static void evict_process_worker(struct work_struct *work)
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
>> b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
>> index 91609dd5730f..01ce2d853602 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
>> @@ -428,7 +428,7 @@ static void svm_range_bo_release(struct kref *kref)
>> if (!dma_fence_is_signaled(&svm_bo->eviction_fence->base))
>> /* We're not in the eviction worker. Signal the fence. */
>> - dma_fence_signal(&svm_bo->eviction_fence->base);
>> + amdkfd_fence_signal(&svm_bo->eviction_fence->base);
>> dma_fence_put(&svm_bo->eviction_fence->base);
>> amdgpu_bo_unref(&svm_bo->bo);
>> kfree(svm_bo);
>> @@ -3628,7 +3628,7 @@ static void svm_range_evict_svm_bo_worker(struct
>> work_struct *work)
>> mmap_read_unlock(mm);
>> mmput(mm);
>> - dma_fence_signal(&svm_bo->eviction_fence->base);
>> + amdkfd_fence_signal(&svm_bo->eviction_fence->base);
>> /* This is the last reference to svm_bo, after
>> svm_range_vram_node_free
>> * has been called in svm_migrate_vram_to_ram
