[PATCH] drm/amdkfd: fix svm_bo release invalid wait context warning

[Philip Yang]

svm_range_bo_release could be called from __do_munmap put_page
atomic context if process release work has finished to free pranges of
the svm_bo. Schedule release_work to wait for svm_bo eviction work done
and then free svm_bo.

Signed-off-by: Philip Yang <Philip.Yang at amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_svm.c | 36 +++++++++++++++++++---------
 drivers/gpu/drm/amd/amdkfd/kfd_svm.h |  1 +
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
index f2db49c7a8fd..8af87a662a0d 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.c
@@ -327,11 +327,33 @@ static bool svm_bo_ref_unless_zero(struct svm_range_bo *svm_bo)
 	return true;
 }
 
+static void svm_range_bo_wq_release(struct work_struct *work)
+{
+	struct svm_range_bo *svm_bo;
+
+	svm_bo = container_of(work, struct svm_range_bo, release_work);
+	pr_debug("svm_bo 0x%p\n", svm_bo);
+
+	if (!dma_fence_is_signaled(&svm_bo->eviction_fence->base)) {
+		/* We're not in the eviction worker.
+		 * Signal the fence and synchronize with any
+		 * pending eviction work.
+		 */
+		dma_fence_signal(&svm_bo->eviction_fence->base);
+		cancel_work_sync(&svm_bo->eviction_work);
+	}
+	dma_fence_put(&svm_bo->eviction_fence->base);
+	amdgpu_bo_unref(&svm_bo->bo);
+	kfree(svm_bo);
+}
+
 static void svm_range_bo_release(struct kref *kref)
 {
 	struct svm_range_bo *svm_bo;
 
 	svm_bo = container_of(kref, struct svm_range_bo, kref);
+	pr_debug("svm_bo 0x%p\n", svm_bo);
+
 	spin_lock(&svm_bo->list_lock);
 	while (!list_empty(&svm_bo->range_list)) {
 		struct svm_range *prange =
@@ -352,17 +374,9 @@ static void svm_range_bo_release(struct kref *kref)
 		spin_lock(&svm_bo->list_lock);
 	}
 	spin_unlock(&svm_bo->list_lock);
-	if (!dma_fence_is_signaled(&svm_bo->eviction_fence->base)) {
-		/* We're not in the eviction worker.
-		 * Signal the fence and synchronize with any
-		 * pending eviction work.
-		 */
-		dma_fence_signal(&svm_bo->eviction_fence->base);
-		cancel_work_sync(&svm_bo->eviction_work);
-	}
-	dma_fence_put(&svm_bo->eviction_fence->base);
-	amdgpu_bo_unref(&svm_bo->bo);
-	kfree(svm_bo);
+
+	INIT_WORK(&svm_bo->release_work, svm_range_bo_wq_release);
+	schedule_work(&svm_bo->release_work);
 }
 
 void svm_range_bo_unref(struct svm_range_bo *svm_bo)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_svm.h b/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
index 6dc91c33e80f..23478ae7a7d9 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_svm.h
@@ -48,6 +48,7 @@ struct svm_range_bo {
 	struct work_struct		eviction_work;
 	struct svm_range_list		*svms;
 	uint32_t			evicting;
+	struct work_struct		release_work;
 };
 
 enum svm_work_list_ops {
-- 
2.17.1