6.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
[ Upstream commit fa998a9eac8809da4f219aad49836fcad2a9bf5c ]
drm_gpuvm_bo_obtain_prealloc() will call drm_gpuvm_bo_put() on our
pre-allocated BO if the <BO,VM> association exists. Given we
only have one ref on preallocated_vm_bo, drm_gpuvm_bo_destroy() will
be called immediately, and we have to hold the VM resv lock when
calling this function.
Fixes: 647810ec2476 ("drm/panthor: Add the MMU/VM logical block")
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
Reviewed-by: Liviu Dudau <liviu.dudau@xxxxxxx>
Reviewed-by: Steven Price <steven.price@xxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20240913112722.492144-1-boris.brezillon@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/gpu/drm/panthor/panthor_mmu.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index cc6e13a977835..ce8e8a93d7076 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -1251,9 +1251,17 @@ static int panthor_vm_prepare_map_op_ctx(struct panthor_vm_op_ctx *op_ctx,
goto err_cleanup;
}
+ /* drm_gpuvm_bo_obtain_prealloc() will call drm_gpuvm_bo_put() on our
+ * pre-allocated BO if the <BO,VM> association exists. Given we
+ * only have one ref on preallocated_vm_bo, drm_gpuvm_bo_destroy() will
+ * be called immediately, and we have to hold the VM resv lock when
+ * calling this function.
+ */
+ dma_resv_lock(panthor_vm_resv(vm), NULL);
mutex_lock(&bo->gpuva_list_lock);
op_ctx->map.vm_bo = drm_gpuvm_bo_obtain_prealloc(preallocated_vm_bo);
mutex_unlock(&bo->gpuva_list_lock);
+ dma_resv_unlock(panthor_vm_resv(vm));
/* If the a vm_bo for this <VM,BO> combination exists, it already
* retains a pin ref, and we can release the one we took earlier.
--
2.43.0
