drm/amdgpu: Avoid reclaim fs while eviction lock

[Why]
Avoid reclaim filesystem while eviction lock is held called from
MMU notifier.

[How]
Setting PF_MEMALLOC_NOFS flags while eviction mutex is locked.
Using memalloc_nofs_save / memalloc_nofs_restore API.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 33 insertions, 7 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 4dc75eda1d91..d16231d6a790 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -83,6 +83,32 @@ struct amdgpu_prt_cb {
 };
 
 /**
+ * vm eviction_lock can be taken in MMU notifiers. Make sure no reclaim-FS
+ * happens while holding this lock anywhere to prevent deadlocks when
+ * an MMU notifier runs in reclaim-FS context.
+ */
+static inline void amdgpu_vm_eviction_lock(struct amdgpu_vm *vm)
+{
+	mutex_lock(&vm->eviction_lock);
+	vm->saved_flags = memalloc_nofs_save();
+}
+
+static inline int amdgpu_vm_eviction_trylock(struct amdgpu_vm *vm)
+{
+	if (mutex_trylock(&vm->eviction_lock)) {
+		vm->saved_flags = memalloc_nofs_save();
+		return 1;
+	}
+	return 0;
+}
+
+static inline void amdgpu_vm_eviction_unlock(struct amdgpu_vm *vm)
+{
+	memalloc_nofs_restore(vm->saved_flags);
+	mutex_unlock(&vm->eviction_lock);
+}
+
+/**
  * amdgpu_vm_level_shift - return the addr shift for each level
  *
  * @adev: amdgpu_device pointer
@@ -678,9 +704,9 @@ int amdgpu_vm_validate_pt_bos(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 		}
 	}
 
-	mutex_lock(&vm->eviction_lock);
+	amdgpu_vm_eviction_lock(vm);
 	vm->evicting = false;
-	mutex_unlock(&vm->eviction_lock);
+	amdgpu_vm_eviction_unlock(vm);
 
 	return 0;
 }
@@ -1559,7 +1585,7 @@ static int amdgpu_vm_bo_update_mapping(struct amdgpu_device *adev,
 	if (!(flags & AMDGPU_PTE_VALID))
 		owner = AMDGPU_FENCE_OWNER_KFD;
 
-	mutex_lock(&vm->eviction_lock);
+	amdgpu_vm_eviction_lock(vm);
 	if (vm->evicting) {
 		r = -EBUSY;
 		goto error_unlock;
@@ -1576,7 +1602,7 @@ static int amdgpu_vm_bo_update_mapping(struct amdgpu_device *adev,
 	r = vm->update_funcs->commit(&params, fence);
 
 error_unlock:
-	mutex_unlock(&vm->eviction_lock);
+	amdgpu_vm_eviction_unlock(vm);
 	return r;
 }
 
@@ -2533,18 +2559,18 @@ bool amdgpu_vm_evictable(struct amdgpu_bo *bo)
 		return false;
 
 	/* Try to block ongoing updates */
-	if (!mutex_trylock(&bo_base->vm->eviction_lock))
+	if (!amdgpu_vm_eviction_trylock(bo_base->vm))
 		return false;
 
 	/* Don't evict VM page tables while they are updated */
 	if (!dma_fence_is_signaled(bo_base->vm->last_direct) ||
 	    !dma_fence_is_signaled(bo_base->vm->last_delayed)) {
-		mutex_unlock(&bo_base->vm->eviction_lock);
+		amdgpu_vm_eviction_unlock(bo_base->vm);
 		return false;
 	}
 
 	bo_base->vm->evicting = true;
-	mutex_unlock(&bo_base->vm->eviction_lock);
+	amdgpu_vm_eviction_unlock(bo_base->vm);
 	return true;
 }