- WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == (FOLL_GET | FOLL_PIN));
-
- if (flags & FOLL_GET)
- return try_get_page(page);
- else if (flags & FOLL_PIN) {
- int refs = 1;
-
- page = compound_head(page);
-
- if (WARN_ON_ONCE(page_ref_count(page) <= 0))
- return false;
-
- if (hpage_pincount_available(page))
- hpage_pincount_add(page, 1);
- else
- refs = GUP_PIN_COUNTING_BIAS;
-
- /*
- * Similar to try_grab_compound_head(): even if using the
- * hpage_pincount_add/_sub() routines, be sure to
- * *also* increment the normal page refcount field at least
- * once, so that the page really is pinned.
- */
- page_ref_add(page, refs);