[Intel-gfx] [PATCH] drm/i915: Add lmem fault handler

[Dan Carpenter]

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 next-20191210]
[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-Add-lmem-fault-handler/20191212-031235
base:   git://anongit.freedesktop.org/drm-intel for-linux-next

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

smatch warnings:
drivers/gpu/drm/i915/gem/i915_gem_lmem.c:40 vm_fault_lmem() error: uninitialized symbol 'vmf_ret'.

# https://github.com/0day-ci/linux/commit/527bcb2414222221b5b3cea4909756095ae07d6a
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 527bcb2414222221b5b3cea4909756095ae07d6a
vim +/vmf_ret +40 drivers/gpu/drm/i915/gem/i915_gem_lmem.c

527bcb24142222 Abdiel Janulgue 2019-12-11  12  vm_fault_t vm_fault_lmem(struct vm_fault *vmf)
527bcb24142222 Abdiel Janulgue 2019-12-11  13  {
527bcb24142222 Abdiel Janulgue 2019-12-11  14  	struct vm_area_struct *area = vmf->vma;
527bcb24142222 Abdiel Janulgue 2019-12-11  15  	struct i915_mmap_offset *priv = area->vm_private_data;
527bcb24142222 Abdiel Janulgue 2019-12-11  16  	struct drm_i915_gem_object *obj = priv->obj;
527bcb24142222 Abdiel Janulgue 2019-12-11  17  	unsigned long size = area->vm_end - area->vm_start;
527bcb24142222 Abdiel Janulgue 2019-12-11  18  	bool write = area->vm_flags & VM_WRITE;
527bcb24142222 Abdiel Janulgue 2019-12-11  19  	vm_fault_t vmf_ret;
                                                ^^^^^^^^^^^^^^^^^^^

527bcb24142222 Abdiel Janulgue 2019-12-11  20  	int i, ret;
527bcb24142222 Abdiel Janulgue 2019-12-11  21  
527bcb24142222 Abdiel Janulgue 2019-12-11  22  	/* Sanity check that we allow writing into this object */
527bcb24142222 Abdiel Janulgue 2019-12-11  23  	if (i915_gem_object_is_readonly(obj) && write)
527bcb24142222 Abdiel Janulgue 2019-12-11  24  		return VM_FAULT_SIGBUS;
527bcb24142222 Abdiel Janulgue 2019-12-11  25  
527bcb24142222 Abdiel Janulgue 2019-12-11  26  	ret = i915_gem_object_pin_pages(obj);
527bcb24142222 Abdiel Janulgue 2019-12-11  27  	if (ret)
527bcb24142222 Abdiel Janulgue 2019-12-11  28  		return i915_error_to_vmf_fault(ret);
527bcb24142222 Abdiel Janulgue 2019-12-11  29  
527bcb24142222 Abdiel Janulgue 2019-12-11  30  	for (i = 0; i < size >> PAGE_SHIFT; i++) {

Can size be less than a page?

527bcb24142222 Abdiel Janulgue 2019-12-11  31  		vmf_ret = vmf_insert_pfn(area,
527bcb24142222 Abdiel Janulgue 2019-12-11  32  					 (unsigned long)area->vm_start + i * PAGE_SIZE,
527bcb24142222 Abdiel Janulgue 2019-12-11  33  					 i915_gem_object_lmem_io_pfn(obj, i));
527bcb24142222 Abdiel Janulgue 2019-12-11  34  		if (vmf_ret != VM_FAULT_NOPAGE)
527bcb24142222 Abdiel Janulgue 2019-12-11  35  			break;
527bcb24142222 Abdiel Janulgue 2019-12-11  36  	}
527bcb24142222 Abdiel Janulgue 2019-12-11  37  
527bcb24142222 Abdiel Janulgue 2019-12-11  38  	i915_gem_object_unpin_pages(obj);
527bcb24142222 Abdiel Janulgue 2019-12-11  39  
527bcb24142222 Abdiel Janulgue 2019-12-11 @40  	return vmf_ret;
527bcb24142222 Abdiel Janulgue 2019-12-11  41  }

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