Quoting Tvrtko Ursulin (2019-03-05 11:04:08)
> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
>
> Legacy behaviour was to allow non-page-aligned mmap requests, as does the
> linux mmap(2) implementation by virtue of automatically rounding up for
> the caller.
>
> To avoid breaking legacy userspace relax the newly introduced fix.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Fixes: 5c4604e757ba ("drm/i915: Prevent a race during I915_GEM_MMAP ioctl with WC set")
> Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Cc: Adam Zabrocki <adamza@xxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.0+
> Cc: Akash Goel <akash.goel@xxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> ---
> drivers/gpu/drm/i915/i915_gem.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index a1ad5e137a97..0196ad97adcb 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1593,7 +1593,8 @@ __vma_matches(struct vm_area_struct *vma, struct file *filp,
> if (vma->vm_file != filp)
> return false;
>
> - return vma->vm_start == addr && (vma->vm_end - vma->vm_start) == size;
> + return vma->vm_start == addr &&
> + (vma->vm_end - vma->vm_start) == PAGE_ALIGN(size);
Gosh and darnation,
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
-Chris
