[Intel-gfx] [PATCH 1/3] drm/i915/gtt: Fix the boundary check for vm area

[Daniel Vetter]

On Tue, May 12, 2015 at 10:35:08AM +0300, Mika Kuoppala wrote:
> The check for start + length >= total_vm_size is
> wrong since start + length can be exactly the size of
> the vm.
> 
> Fix the check to allow allocation to boundary.
> 
> Fixes a regression in commit 4dd738e9cd79
> ("drm/i915: Fix 32b overflow check in gen8_ppgtt_alloc_page_directories")
> 
> Testcase: igt/gem_evict_everything/swapping-interruptible
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90399
> Tested-by: Lu Hua <huax.lu at intel.com>
> Cc: Chris Wilson <chris at chris.wilson.co.uk>
> Cc: Dave Gordon <david.s.gordon at intel.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Michel Thierry <michel.thierry at intel.com>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>

Queued for -next, thanks for the patch.
-Daniel

> ---
>  drivers/gpu/drm/i915/i915_gem_gtt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index e3bcc3b..17b7df0 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -757,7 +757,7 @@ static int gen8_ppgtt_alloc_page_directories(struct i915_hw_ppgtt *ppgtt,
>  	WARN_ON(!bitmap_empty(new_pds, GEN8_LEGACY_PDPES));
>  
>  	/* FIXME: upper bound must not overflow 32 bits  */
> -	WARN_ON((start + length) >= (1ULL << 32));
> +	WARN_ON((start + length) > (1ULL << 32));
>  
>  	gen8_for_each_pdpe(pd, pdp, start, length, temp, pdpe) {
>  		if (pd)
> -- 
> 1.9.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch