This is a note to let you know that I've just added the patch titled
drm/panthor: Lock the VM resv before calling drm_gpuvm_bo_obtain_prealloc()
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-panthor-lock-the-vm-resv-before-calling-drm_gpuv.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ed789bcc0f8ea18bc9d102e3fb36b302fc460ac2
Author: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
Date: Fri Sep 13 13:27:22 2024 +0200
drm/panthor: Lock the VM resv before calling drm_gpuvm_bo_obtain_prealloc()
[ 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>
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.
