mm/vmscan: make too_many_isolated return bool

too_many_isolated() should return bool as does the similar
too_many_isolated() in mm/compaction.c.

Link: https://lkml.kernel.org/r/20240205042618.108140-1-gehao@kylinos.cnSigned-off-by: Hao Ge <gehao@kylinos.cn>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/vmscan.c

@@ -1744,17 +1744,17 @@ bool folio_isolate_lru(struct folio *folio)
  * the LRU list will go small and be scanned faster than necessary, leading to
  * unnecessary swapping, thrashing and OOM.
  */
-static int too_many_isolated(struct pglist_data *pgdat, int file,
+static bool too_many_isolated(struct pglist_data *pgdat, int file,
 		struct scan_control *sc)
 {
 	unsigned long inactive, isolated;
 	bool too_many;
 
 	if (current_is_kswapd())
-		return 0;
+		return false;
 
 	if (!writeback_throttling_sane(sc))
-		return 0;
+		return false;
 
 	if (file) {
 		inactive = node_page_state(pgdat, NR_INACTIVE_FILE);