Re: [PATCH v3 01/10] drm/shmem-helper: Add huge page fault handler

[Andi Shyti <andi.shyti@kernel.org>]

Hi Loic,

...

> +					   unsigned int order)
>  {
>  	struct vm_area_struct *vma = vmf->vma;
>  	struct drm_gem_object *obj = vma->vm_private_data;
> @@ -582,6 +583,10 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
>  	vm_fault_t ret;

we could initialize ret to VM_FAULT_FALLBACK and avoid the else's
and the default case.

>  	struct page *page;
>  	pgoff_t page_offset;
> +	unsigned long pfn;
> +#if defined(CONFIG_ARCH_SUPPORTS_PMD_PFNMAP) || defined(CONFIG_ARCH_SUPPORTS_PUD_PFNMAP)
> +	unsigned long paddr;
> +#endif

we could declare paddr inside the switch case in order to avoid
some extra ifdefs.

>  	/* We don't use vmf->pgoff since that has the fake offset */
>  	page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
> @@ -592,17 +597,57 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
>  	    drm_WARN_ON_ONCE(obj->dev, !shmem->pages) ||
>  	    shmem->madv < 0) {
>  		ret = VM_FAULT_SIGBUS;
> -	} else {
> -		page = shmem->pages[page_offset];
> +		goto out;
> +	}
>  
> -		ret = vmf_insert_pfn(vma, vmf->address, page_to_pfn(page));
> +	page = shmem->pages[page_offset];
> +	pfn = page_to_pfn(page);
> +
> +	switch (order) {
> +	case 0:

'0' needs to be defined, what does '0' mean? (I know what it
means, but for consistency I think it should have its own name).

Andi

> +		ret = vmf_insert_pfn(vma, vmf->address, pfn);
> +		break;