[PATCH] drm/shmem-helper: Don't remove the offset in vm_area_struct pgoff

[kernel test robot]

Hi Neil,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.11 next-20210217]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Neil-Roberts/drm-shmem-helper-Don-t-remove-the-offset-in-vm_area_struct-pgoff/20210218-012028
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git f40ddce88593482919761f74910f42f4b84c004b
config: i386-randconfig-m021-20210215 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0

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

New smatch warnings:
drivers/gpu/drm/drm_gem_shmem_helper.c:534 drm_gem_shmem_fault() warn: unsigned 'page_offset' is never less than zero.

Old smatch warnings:
include/drm/drm_vma_manager.h:225 drm_vma_node_unmap() warn: should 'drm_vma_node_size(node) << 12' be a 64 bit type?

vim +/page_offset +534 drivers/gpu/drm/drm_gem_shmem_helper.c

   521	
   522	static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
   523	{
   524		struct vm_area_struct *vma = vmf->vma;
   525		struct drm_gem_object *obj = vma->vm_private_data;
   526		struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
   527		loff_t num_pages = obj->size >> PAGE_SHIFT;
   528		struct page *page;
   529		pgoff_t page_offset;
   530	
   531		/* We don't use vmf->pgoff since that has the fake offset */
   532		page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
   533	
 > 534		if (page_offset < 0 || page_offset >= num_pages ||
   535		    WARN_ON_ONCE(!shmem->pages))
   536			return VM_FAULT_SIGBUS;
   537	
   538		page = shmem->pages[page_offset];
   539	
   540		return vmf_insert_page(vma, vmf->address, page);
   541	}
   542	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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