Re: [PATCH] drm/radeon: don't evict if not initialized

[Christian König]

Am 20.03.21 um 21:10 schrieb Tong Zhang:
> TTM_PL_VRAM may not initialized at all when calling
> radeon_bo_evict_vram(). We need to check before doing eviction.
>
> [    2.160837] BUG: kernel NULL pointer dereference, address: 0000000000000020
> [    2.161212] #PF: supervisor read access in kernel mode
> [    2.161490] #PF: error_code(0x0000) - not-present page
> [    2.161767] PGD 0 P4D 0
> [    2.163088] RIP: 0010:ttm_resource_manager_evict_all+0x70/0x1c0 [ttm]
> [    2.168506] Call Trace:
> [    2.168641]  radeon_bo_evict_vram+0x1c/0x20 [radeon]
> [    2.168936]  radeon_device_fini+0x28/0xf9 [radeon]
> [    2.169224]  radeon_driver_unload_kms+0x44/0xa0 [radeon]
> [    2.169534]  radeon_driver_load_kms+0x174/0x210 [radeon]
> [    2.169843]  drm_dev_register+0xd9/0x1c0 [drm]
> [    2.170104]  radeon_pci_probe+0x117/0x1a0 [radeon]
>
> Signed-off-by: Tong Zhang <ztong0001@xxxxxxxxx>
> ---
>   drivers/gpu/drm/radeon/radeon_object.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
> index 9b81786782de..04e9a8118b0e 100644
> --- a/drivers/gpu/drm/radeon/radeon_object.c
> +++ b/drivers/gpu/drm/radeon/radeon_object.c
> @@ -384,7 +384,9 @@ int radeon_bo_evict_vram(struct radeon_device *rdev)
>   	}
>   #endif
>   	man = ttm_manager_type(bdev, TTM_PL_VRAM);
> -	return ttm_resource_manager_evict_all(bdev, man);
> +	if (man)
> +		return ttm_resource_manager_evict_all(bdev, man);
> +	return 0;

You should probably code this the other way around, e.g.

If (!man)
    return 0;
...

Apart from that looks good to me.

Christian.

>   }
>   
>   void radeon_bo_force_delete(struct radeon_device *rdev)