Re: [PATCH v7 4/6] userfaultfd: add UFFDIO_CONTINUE ioctl

[Peter Xu]

On Thu, Feb 18, 2021 at 04:48:22PM -0800, Axel Rasmussen wrote:
> @@ -4645,8 +4646,18 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
>  	spinlock_t *ptl;
>  	int ret;
>  	struct page *page;
> +	int writable;
>  
> -	if (!*pagep) {
> +	mapping = dst_vma->vm_file->f_mapping;
> +	idx = vma_hugecache_offset(h, dst_vma, dst_addr);
> +
> +	if (is_continue) {
> +		ret = -EFAULT;
> +		page = find_lock_page(mapping, idx);
> +		*pagep = NULL;

Why set *pagep to NULL?  Shouldn't it be NULL always?.. If that's the case,
maybe WARN_ON_ONCE(*pagep) suite more.

Otherwise the patch looks good to me.

Thanks,

-- 
Peter Xu