On 2025-10-30 11:07, Christian König wrote:
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.
I see. Could there be race conditions here, if enable_signaling happens
concurrently and we end up calling mmdrop twice?
Regards,
Felix
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
