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Subject: Re: [PATCH v2] drm/radeon: don't evict if not initialized
To:     Tong Zhang <ztong0001@gmail.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, amd-gfx@lists.freedesktop.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
References: <20210321151907.367586-1-ztong0001@gmail.com>
From:   =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>
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Am 21.03.21 um 16:19 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]
>
> Suggested-by: Christian König <christian.koenig@amd.com>
> Signed-off-by: Tong Zhang <ztong0001@gmail.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
> v2: coding style fix
>
>   drivers/gpu/drm/radeon/radeon_object.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
> index 9b81786782de..499ce55e34cc 100644
> --- a/drivers/gpu/drm/radeon/radeon_object.c
> +++ b/drivers/gpu/drm/radeon/radeon_object.c
> @@ -384,6 +384,8 @@ int radeon_bo_evict_vram(struct radeon_device *rdev)
>   	}
>   #endif
>   	man = ttm_manager_type(bdev, TTM_PL_VRAM);
> +	if (!man)
> +		return 0;
>   	return ttm_resource_manager_evict_all(bdev, man);
>   }
>