[PATCH] drm/amdgpu: stop allocating PDs/PTs with the eviction lock held

[Christian König]

We need to make sure to not allocate PDs/PTs while holding
the eviction lock or otherwise we will run into lock inversion
in the MM as soon as we enable the MMU notifier.

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 31 +++++++++++++++++++++-----
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 77c400675b79..e7ab0c1e2793 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -897,27 +897,42 @@ static int amdgpu_vm_alloc_pts(struct amdgpu_device *adev,
 	struct amdgpu_vm_pt *entry = cursor->entry;
 	struct amdgpu_bo_param bp;
 	struct amdgpu_bo *pt;
+	bool need_entries;
 	int r;
 
-	if (cursor->level < AMDGPU_VM_PTB && !entry->entries) {
+	need_entries = cursor->level < AMDGPU_VM_PTB && !entry->entries;
+	if (!need_entries && entry->base.bo)
+		return 0;
+
+	/* We need to make sure that we don't allocate PDs/PTs while holding the
+	 * eviction lock or we run into lock recursion in the MM.
+	 */
+	amdgpu_vm_eviction_unlock(vm);
+
+	if (need_entries) {
 		unsigned num_entries;
 
 		num_entries = amdgpu_vm_num_entries(adev, cursor->level);
 		entry->entries = kvmalloc_array(num_entries,
 						sizeof(*entry->entries),
 						GFP_KERNEL | __GFP_ZERO);
-		if (!entry->entries)
-			return -ENOMEM;
+		if (!entry->entries) {
+			r = -ENOMEM;
+			goto error_lock;
+		}
 	}
 
-	if (entry->base.bo)
-		return 0;
+	if (entry->base.bo) {
+		r = 0;
+		goto error_lock;
+	}
 
 	amdgpu_vm_bo_param(adev, vm, cursor->level, direct, &bp);
 
 	r = amdgpu_bo_create(adev, &bp, &pt);
+	amdgpu_vm_eviction_lock(vm);
 	if (r)
-		return r;
+		goto error_free_pt;
 
 	/* Keep a reference to the root directory to avoid
 	 * freeing them up in the wrong order.
@@ -936,6 +951,10 @@ static int amdgpu_vm_alloc_pts(struct amdgpu_device *adev,
 	amdgpu_bo_unref(&pt);
 	entry->base.bo = NULL;
 	return r;
+
+error_lock:
+	amdgpu_vm_eviction_lock(vm);
+	return r;
 }
 
 /**
-- 
2.17.1