1 files changed, 24 insertions, 8 deletions

diff --git a/mm/swap.c b/mm/swap.c
index bcf3ac288b56..ff4810e4a4bc 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -74,8 +74,8 @@ static DEFINE_PER_CPU(struct lru_pvecs, lru_pvecs) = {
 };
 
 /*
- * This path almost never happens for VM activity - pages are normally
- * freed via pagevecs.  But it gets used by networking.
+ * This path almost never happens for VM activity - pages are normally freed
+ * via pagevecs.  But it gets used by networking - and for compound pages.
  */
 static void __page_cache_release(struct page *page)
 {
@@ -89,6 +89,14 @@ static void __page_cache_release(struct page *page)
 		__clear_page_lru_flags(page);
 		unlock_page_lruvec_irqrestore(lruvec, flags);
 	}
+	/* See comment on PageMlocked in release_pages() */
+	if (unlikely(PageMlocked(page))) {
+		int nr_pages = thp_nr_pages(page);
+
+		__ClearPageMlocked(page);
+		mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
+		count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages);
+	}
 	__ClearPageWaiters(page);
 }
 
@@ -489,12 +497,8 @@ void lru_cache_add_inactive_or_unevictable(struct page *page,
 	unevictable = (vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED;
 	if (unlikely(unevictable) && !TestSetPageMlocked(page)) {
 		int nr_pages = thp_nr_pages(page);
-		/*
-		 * We use the irq-unsafe __mod_zone_page_state because this
-		 * counter is not modified from interrupt context, and the pte
-		 * lock is held(spinlock), which implies preemption disabled.
-		 */
-		__mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);
+
+		mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);
 		count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
 	}
 	lru_cache_add(page);
@@ -969,6 +973,18 @@ void release_pages(struct page **pages, int nr)
 			__clear_page_lru_flags(page);
 		}
 
+		/*
+		 * In rare cases, when truncation or holepunching raced with
+		 * munlock after VM_LOCKED was cleared, Mlocked may still be
+		 * found set here.  This does not indicate a problem, unless
+		 * "unevictable_pgs_cleared" appears worryingly large.
+		 */
+		if (unlikely(PageMlocked(page))) {
+			__ClearPageMlocked(page);
+			dec_zone_page_state(page, NR_MLOCK);
+			count_vm_event(UNEVICTABLE_PGCLEARED);
+		}
+
 		__ClearPageWaiters(page);
 
 		list_add(&page->lru, &pages_to_free);