[Intel-gfx] [PATCH] drm/i915: vfree() no longer ignores the low bits of the address

[Tvrtko Ursulin]

On 18/08/16 10:01, Chris Wilson wrote:
> Since vfree() now likes to WARN when passed a none page-aligned pointer,
> we need to discard the low bits to comply with it.
>
> Fixes: d31d7cb1460c ("drm/i915: Support for creating write combined type vmaps")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>   drivers/gpu/drm/i915/i915_drv.h |  5 +++++
>   drivers/gpu/drm/i915/i915_gem.c | 11 +++++++----
>   2 files changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 35caa9b2f36a..cc1e72dbf18e 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -3896,6 +3896,11 @@ static inline bool __i915_request_irq_complete(struct drm_i915_gem_request *req)
>   void i915_memcpy_init_early(struct drm_i915_private *dev_priv);
>   bool i915_memcpy_from_wc(void *dst, const void *src, unsigned long len);
>
> +#define ptr_mask_bits(ptr) ({						\
> +	unsigned long __v = (unsigned long)(ptr);			\
> +	(typeof(ptr))(__v & PAGE_MASK);					\
> +})
> +
>   #define ptr_unpack_bits(ptr, bits) ({					\
>   	unsigned long __v = (unsigned long)(ptr);			\
>   	(bits) = __v & ~PAGE_MASK;					\
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index a8d0f70c22f9..cffa57b14246 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2094,11 +2094,14 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
>   	list_del(&obj->global_list);
>
>   	if (obj->mapping) {
> -		/* low bits are ignored by is_vmalloc_addr and kmap_to_page */
> -		if (is_vmalloc_addr(obj->mapping))
> -			vunmap(obj->mapping);
> +		void *ptr;
> +
> +		ptr = ptr_mask_bits(obj->mapping);
> +		if (is_vmalloc_addr(ptr))
> +			vunmap(ptr);
>   		else
> -			kunmap(kmap_to_page(obj->mapping));
> +			kunmap(kmap_to_page(ptr));
> +
>   		obj->mapping = NULL;
>   	}
>
>

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko