[Intel-gfx] [PATCH 1/3] drm/i915: Introduce remap_io_sg() to prefault discontiguous objects

[kbuild test robot]

Hi Abdiel,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on drm-intel/for-linux-next]
[also build test WARNING on drm-tip/drm-tip v5.5-rc3 next-20191220]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Abdiel-Janulgue/drm-i915-Introduce-remap_io_sg-to-prefault-discontiguous-objects/20191225-032829
base:   git://anongit.freedesktop.org/drm-intel for-linux-next
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.1-129-g341daf20-dirty
        make ARCH=x86_64 allmodconfig
        make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp at intel.com>


sparse warnings: (new ones prefixed by >>)

>> drivers/gpu/drm/i915/i915_mm.c:130:32: sparse: sparse: Using plain integer as NULL pointer

vim +130 drivers/gpu/drm/i915/i915_mm.c

   114	
   115	/**
   116	 * remap_io_sg - remap an IO mapping to userspace
   117	 * @vma: user vma to map to
   118	 * @addr: target user address to start at
   119	 * @io_start: IO start
   120	 * @sgl: Start sg entry
   121	 * @size: size of map area
   122	 * @iomap: the source io_mapping
   123	 *
   124	 *  Note: this is only safe if the mm semaphore is held when called.
   125	 */
   126	int remap_io_sg(struct vm_area_struct *vma,
   127			unsigned long addr, resource_size_t io_start, struct scatterlist *sgl,
   128			unsigned long size, struct io_mapping *iomap)
   129	{
 > 130		struct remap_pfn r = { 0 };

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