[patch 5/8] mm: vmscan: improve comment on low-page cache handling

[Johannes Weiner]

Fix comment style and elaborate on why anonymous memory is
force-scanned when file cache runs low.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
 mm/vmscan.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5e1beed..05475e1 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1697,13 +1697,15 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
 	file  = get_lru_size(lruvec, LRU_ACTIVE_FILE) +
 		get_lru_size(lruvec, LRU_INACTIVE_FILE);
 
+	/*
+	 * If it's foreseeable that reclaiming the file cache won't be
+	 * enough to get the zone back into a desirable shape, we have
+	 * to swap.  Better start now and leave the - probably heavily
+	 * thrashing - remaining file pages alone.
+	 */
 	if (global_reclaim(sc)) {
-		free  = zone_page_state(zone, NR_FREE_PAGES);
+		free = zone_page_state(zone, NR_FREE_PAGES);
 		if (unlikely(file + free <= high_wmark_pages(zone))) {
-			/*
-			 * If we have very few page cache pages, force-scan
-			 * anon pages.
-			 */
 			fraction[0] = 1;
 			fraction[1] = 0;
 			denominator = 1;
-- 
1.7.11.7

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