Re: [PATCH 4/4] drm/xe: Keep VRAM fault injection within the usable range

["Ghimiray, Himal Prasad" <himal.prasad.ghimiray@intel.com>]

On 01-10-2026 15:15, Tejas Upadhyay wrote:
> xe_ttm_vram_inject_fault() picked its starting address from
> vr->actual_physical_size, which includes the CCS/GSM/DSM infrastructure
> zone beyond vr->usable_size. The buddy allocator (vram_mgr->mm) only
> manages usable_size, so the first probed address can land in that
> infra zone; xe_ttm_vram_addr_to_region() then returns NULL for it and
> xe_ttm_vram_handle_addr_fault() requests an SBR instead of exercising
> page offlining.
> 
> Start the probe at usable_size - PAGE_SIZE and stay within
> usable_size so the injected fault always lands on real, buddy-managed
> VRAM.
> 
> Fixes: 6ef3eb10aea4 ("drm/xe: Add fault-inject based VRAM page offline injection")
> Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> index 7211ab5f66e9..ec15eab1a2ed 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> @@ -988,11 +988,12 @@ int xe_ttm_vram_inject_fault(struct xe_device *xe)
>   	struct gpu_buddy *mm = &vram_mgr->mm;
>   	u64 addr;
>   
> -	if (vr->actual_physical_size < PAGE_SIZE)
> +	/* Stay within the buddy-managed range; CCS/GSM/DSM sit beyond usable_size */
> +	if (vr->usable_size < PAGE_SIZE)
>   		return -ENOSPC;
>   
> -	addr = vr->actual_physical_size - PAGE_SIZE;
> -	while (addr < vr->actual_physical_size) {
> +	addr = vr->usable_size - PAGE_SIZE;

Nit: align addr to PAGE_SIZE

With Nit addressed
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>

> +	while (addr < vr->usable_size) {
>   		struct gpu_buddy_block *block;
>   		bool found = false;
>