linux-kernel - [PATCH 3/4] drm/amdgpu: reserve root PD while releasing it

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Date:   Thu, 30 Nov 2017 19:23:05 -0500
From:   Lyude Paul <lyude@...hat.com>
To:     stable@...r.kernel.org
Cc:     Christian König <christian.koenig@....com>,
        Alex Deucher <alexander.deucher@....com>,
        David Airlie <airlied@...ux.ie>,
        Chunming Zhou <David1.Zhou@....com>,
        "Zhang, Jerry" <Jerry.Zhang@....com>,
        Felix Kuehling <Felix.Kuehling@....com>,
        Harish Kasiviswanathan <Harish.Kasiviswanathan@....com>,
        Alex Xie <AlexBin.Xie@....com>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] drm/amdgpu: reserve root PD while releasing it

From: Christian König <christian.koenig@....com>

Otherwise somebody could try to evict it at the same time and try to use
half torn down structures.

commit 2642cf110d08a403f585a051e4cbf45a90b3adea upstream

Signed-off-by: Christian König <christian.koenig@....com>
Reviewed-and-Tested-by: Michel Dänzer <michel.daenzer@....com>
Reviewed-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Lyude Paul <lyude@...hat.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index bd20ff018512..591c6dc2c1f7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2586,7 +2586,8 @@ void amdgpu_vm_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm)
 {
 	struct amdgpu_bo_va_mapping *mapping, *tmp;
 	bool prt_fini_needed = !!adev->gart.gart_funcs->set_prt;
-	int i;
+	struct amdgpu_bo *root;
+	int i, r;
 
 	amd_sched_entity_fini(vm->entity.sched, &vm->entity);
 
@@ -2609,7 +2610,15 @@ void amdgpu_vm_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm)
 		amdgpu_vm_free_mapping(adev, vm, mapping, NULL);
 	}
 
-	amdgpu_vm_free_levels(&vm->root);
+	root = amdgpu_bo_ref(vm->root.bo);
+	r = amdgpu_bo_reserve(root, true);
+	if (r) {
+		dev_err(adev->dev, "Leaking page tables because BO reservation failed\n");
+	} else {
+		amdgpu_vm_free_levels(&vm->root);
+		amdgpu_bo_unreserve(root);
+	}
+	amdgpu_bo_unref(&root);
 	dma_fence_put(vm->last_dir_update);
 	for (i = 0; i < AMDGPU_MAX_VMHUBS; i++)
 		amdgpu_vm_free_reserved_vmid(adev, vm, i);
-- 
2.14.3