diff --git a/mm/rmap.c b/mm/rmap.c
index 8754e1f..4644e10 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -988,6 +988,12 @@
 {
 	int first = atomic_inc_and_test(&page->_mapcount);
 	if (first) {
+		/*
+		 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
+		 * these counters are not modified in interrupt context, and
+		 * pte lock(a spinlock) is held, which implies preemption
+		 * disabled.
+		 */
 		if (PageTransHuge(page))
 			__inc_zone_page_state(page,
 					      NR_ANON_TRANSPARENT_HUGEPAGES);
@@ -1079,6 +1085,11 @@
 	/*
 	 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED
 	 * and not charged by memcg for now.
+	 *
+	 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
+	 * these counters are not modified in interrupt context, and
+	 * these counters are not modified in interrupt context, and
+	 * pte lock(a spinlock) is held, which implies preemption disabled.
 	 */
 	if (unlikely(PageHuge(page)))
 		goto out;