The PG_unevictable flag is analogous to, and mutually exclusive with, the
PG_active flag in that it indicates on which LRU list a page resides when
-PG_lru is set. The unevictable list is compile-time configurable based on the
-UNEVICTABLE_LRU Kconfig option.
+PG_lru is set.
The Unevictable LRU infrastructure maintains unevictable pages on an additional
LRU list for a few reasons: