* pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
* callbacks, the associated entries/pages are just ignored.
* The return values of these callbacks are commonly defined like below:
+ *
* - 0 : succeeded to handle the current entry, and if you don't reach the
* end address yet, continue to walk.
* - >0 : succeeded to handle the current entry, and return to the caller
* @riovcnt: size of rvec array
* @flags: currently unused
* @vm_write: 0 if reading from other process, 1 if writing to other process
+ *
* Returns the number of bytes read/written or error code. May
* return less bytes than expected if an error occurs during the copying
* process.
* @riovcnt: size of rvec array
* @flags: currently unused
* @vm_write: 0 if reading from other process, 1 if writing to other process
+ *
* Returns the number of bytes read/written or error code. May
* return less bytes than expected if an error occurs during the copying
* process.
* found will be decremented.
*
* Restrictions:
+ *
* (1) Must be called with an elevated refcount on the page. This is a
* fundamentnal difference from isolate_lru_pages (which is called
* without a stable reference).