[PATCH v3] drm/amdgpu: fix the memleak caused by fence not released

[Christian König]

Am 18.02.25 um 15:53 schrieb Arvind Yadav:
> Encountering a taint issue during the unloading of gpu_sched
> due to the fence not being released/put. In this context,
> amdgpu_vm_clear_freed is responsible for creating a job to
> update the page table (PT). It allocates kmem_cache for
> drm_sched_fence and returns the finished fence associated
> with job->base.s_fence. In case of Usermode queue this finished
> fence is added to the timeline sync object through
> amdgpu_gem_update_bo_mapping, which is utilized by user
> space to ensure the completion of the PT update.
>
> [  508.900587] =============================================================================
> [  508.900605] BUG drm_sched_fence (Tainted: G                 N): Objects remaining in drm_sched_fence on __kmem_cache_shutdown()
> [  508.900617] -----------------------------------------------------------------------------
>
> [  508.900627] Slab 0xffffe0cc04548780 objects=32 used=2 fp=0xffff8ea81521f000 flags=0x17ffffc0000240(workingset|head|node=0|zone=2|lastcpupid=0x1fffff)
> [  508.900645] CPU: 3 UID: 0 PID: 2337 Comm: rmmod Tainted: G                 N 6.12.0+ #1
> [  508.900651] Tainted: [N]=TEST
> [  508.900653] Hardware name: Gigabyte Technology Co., Ltd. X570 AORUS ELITE/X570 AORUS ELITE, BIOS F34 06/10/2021
> [  508.900656] Call Trace:
> [  508.900659]  <TASK>
> [  508.900665]  dump_stack_lvl+0x70/0x90
> [  508.900674]  dump_stack+0x14/0x20
> [  508.900678]  slab_err+0xcb/0x110
> [  508.900687]  ? srso_return_thunk+0x5/0x5f
> [  508.900692]  ? try_to_grab_pending+0xd3/0x1d0
> [  508.900697]  ? srso_return_thunk+0x5/0x5f
> [  508.900701]  ? mutex_lock+0x17/0x50
> [  508.900708]  __kmem_cache_shutdown+0x144/0x2d0
> [  508.900713]  ? flush_rcu_work+0x50/0x60
> [  508.900719]  kmem_cache_destroy+0x46/0x1f0
> [  508.900728]  drm_sched_fence_slab_fini+0x19/0x970 [gpu_sched]
> [  508.900736]  __do_sys_delete_module.constprop.0+0x184/0x320
> [  508.900744]  ? srso_return_thunk+0x5/0x5f
> [  508.900747]  ? debug_smp_processor_id+0x1b/0x30
> [  508.900754]  __x64_sys_delete_module+0x16/0x20
> [  508.900758]  x64_sys_call+0xdf/0x20d0
> [  508.900763]  do_syscall_64+0x51/0x120
> [  508.900769]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
>
> v2: call dma_fence_put in amdgpu_gem_va_update_vm
> v3: Addressed review comments from Christian.
>     - calling amdgpu_gem_update_timeline_node before switch.
>     - puting a dma_fence in case of error or !timeline_syncobj.
>
> Cc: Alex Deucher <alexander.deucher at amd.com>
> Cc: Christian König <christian.koenig at amd.com>
> Cc: Shashank Sharma <shashank.sharma at amd.com>
> Cc: Sunil Khatri <sunil.khatri at amd.com>
> Signed-off-by: Le Ma <le.ma at amd.com>
> Signed-off-by: Arvind Yadav <arvind.yadav at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 33 +++++++++++++------------
>  1 file changed, 17 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index 8b67aae6c2fe..40522b4f331b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -125,9 +125,6 @@ amdgpu_gem_update_bo_mapping(struct drm_file *filp,
>  	struct amdgpu_vm *vm = &fpriv->vm;
>  	struct dma_fence *last_update;
>  
> -	if (!syncobj)
> -		return;
> -
>  	/* Find the last update fence */
>  	switch (operation) {
>  	case AMDGPU_VA_OP_MAP:
> @@ -839,6 +836,7 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
>  	struct drm_exec exec;
>  	uint64_t va_flags;
>  	uint64_t vm_size;
> +	int syncobj_status;
>  	int r = 0;
>  
>  	if (args->va_address < AMDGPU_VA_RESERVED_BOTTOM) {
> @@ -931,6 +929,12 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
>  		bo_va = NULL;
>  	}
>  
> +	syncobj_status = amdgpu_gem_update_timeline_node(filp,
> +					args->vm_timeline_syncobj_out,
> +					args->vm_timeline_point,
> +					&timeline_syncobj,
> +					&timeline_chain);
> +

You don't need syncobj_status here, just assign the return value to r and abort if we can't find any syncobj.

>  	switch (args->operation) {
>  	case AMDGPU_VA_OP_MAP:
>  		va_flags = amdgpu_gem_va_map_flags(adev, args->flags);
> @@ -957,22 +961,19 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
>  		break;
>  	}
>  	if (!r && !(args->flags & AMDGPU_VM_DELAY_UPDATE) && !adev->debug_vm) {
> -
> -		r = amdgpu_gem_update_timeline_node(filp,
> -						    args->vm_timeline_syncobj_out,
> -						    args->vm_timeline_point,
> -						    &timeline_syncobj,
> -						    &timeline_chain);
> -
>  		fence = amdgpu_gem_va_update_vm(adev, &fpriv->vm, bo_va,
>  						args->operation);
>  
> -		if (!r)
> -			amdgpu_gem_update_bo_mapping(filp, bo_va,
> -						     args->operation,
> -						     args->vm_timeline_point,
> -						     fence, timeline_syncobj,
> -						     timeline_chain);
> +		if (syncobj_status || !timeline_syncobj) {
> +			dma_fence_put(fence);
> +			goto error;
> +		}

That should probably be something like this:

if (timeline_syncobj)
    amdgpu_gem_update_bo_mapping(..);
else
    dma_fence_put(fence);

Regards,
Christian.

> +
> +		amdgpu_gem_update_bo_mapping(filp, bo_va,
> +					     args->operation,
> +					     args->vm_timeline_point,
> +					     fence, timeline_syncobj,
> +					     timeline_chain);
>  	}
>  
>  error: