[PATCH -next v2] mm/vmscan: fix some -Wenum-conversion warnings

[Qian Cai]

The -next commit "mm: vmscan: enforce inactive:active ratio at the
reclaim root" [1] introduced some Clang -Wenum-conversion warnings,

mm/vmscan.c:2216:39: warning: implicit conversion from enumeration type
'enum lru_list' to different enumeration type 'enum node_stat_item'
[-Wenum-conversion]
        inactive = lruvec_page_state(lruvec, inactive_lru);
                   ~~~~~~~~~~~~~~~~~         ^~~~~~~~~~~~
mm/vmscan.c:2217:37: warning: implicit conversion from enumeration type
'enum lru_list' to different enumeration type 'enum node_stat_item'
[-Wenum-conversion]
        active = lruvec_page_state(lruvec, active_lru);
                 ~~~~~~~~~~~~~~~~~         ^~~~~~~~~~
mm/vmscan.c:2746:42: warning: implicit conversion from enumeration type
'enum lru_list' to different enumeration type 'enum node_stat_item'
[-Wenum-conversion]
        file = lruvec_page_state(target_lruvec, LRU_INACTIVE_FILE);
               ~~~~~~~~~~~~~~~~~                ^~~~~~~~~~~~~~~~~

Since it guarantees the relative order between the LRU items, fix it by
using NR_LRU_BASE for the translation.

[1] http://lkml.kernel.org/r/20191107205334.158354-4-hannes@xxxxxxxxxxx

Signed-off-by: Qian Cai <cai@xxxxxx>
---

v2: use NR_LRU_BASE/NR_INACTIVE_FILE per Johannes.

 mm/vmscan.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 122b3920aaa4..c8e88f4d9932 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2213,8 +2213,8 @@ static bool inactive_is_low(struct lruvec *lruvec, enum lru_list inactive_lru)
 	unsigned long inactive_ratio;
 	unsigned long gb;
 
-	inactive = lruvec_page_state(lruvec, inactive_lru);
-	active = lruvec_page_state(lruvec, active_lru);
+	inactive = lruvec_page_state(lruvec, NR_LRU_BASE + inactive_lru);
+	active = lruvec_page_state(lruvec, NR_LRU_BASE + active_lru);
 
 	gb = (inactive + active) >> (30 - PAGE_SHIFT);
 	if (gb)
@@ -2743,7 +2743,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 	 * thrashing, try to reclaim those first before touching
 	 * anonymous pages.
 	 */
-	file = lruvec_page_state(target_lruvec, LRU_INACTIVE_FILE);
+	file = lruvec_page_state(target_lruvec, NR_INACTIVE_FILE);
 	if (file >> sc->priority && !(sc->may_deactivate & DEACTIVATE_FILE))
 		sc->cache_trim_mode = 1;
 	else
-- 
1.8.3.1