1 files changed, 19 insertions, 11 deletions

diff --git a/mm/swap.c b/mm/swap.c
index 6b2dc3897cd5..8a12b33936b4 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -887,18 +887,14 @@ void lru_add_drain_all(void)
         mutex_unlock(&lock);
 }
 
-/*
- * Batched page_cache_release().  Decrement the reference count on all the
- * passed pages.  If it fell to zero then remove the page from the LRU and
- * free it.
- *
- * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
- * for the remainder of the operation.
+/**
+ * release_pages - batched page_cache_release()
+ * @pages: array of pages to release
+ * @nr: number of pages
+ * @cold: whether the pages are cache cold
  *
- * The locking in this function is against shrink_inactive_list(): we recheck
- * the page count inside the lock to see whether shrink_inactive_list()
- * grabbed the page via the LRU.  If it did, give up: shrink_inactive_list()
- * will free it.
+ * Decrement the reference count on all the pages in @pages.  If it
+ * fell to zero, remove the page from the LRU and free it.
  */
 void release_pages(struct page **pages, int nr, bool cold)
 {
@@ -907,6 +903,7 @@ void release_pages(struct page **pages, int nr, bool cold)
         struct zone *zone = NULL;
         struct lruvec *lruvec;
         unsigned long uninitialized_var(flags);
+        unsigned int uninitialized_var(lock_batch);
 
         for (i = 0; i < nr; i++) {
                 struct page *page = pages[i];
@@ -920,6 +917,16 @@ void release_pages(struct page **pages, int nr, bool cold)
                         continue;
                 }
 
+                /*
+                 * Make sure the IRQ-safe lock-holding time does not get
+                 * excessive with a continuous string of pages from the
+                 * same zone. The lock is held only if zone != NULL.
+                 */
+                if (zone && ++lock_batch == SWAP_CLUSTER_MAX) {
+                        spin_unlock_irqrestore(&zone->lru_lock, flags);
+                        zone = NULL;
+                }
+
                 if (!put_page_testzero(page))
                         continue;
 
@@ -930,6 +937,7 @@ void release_pages(struct page **pages, int nr, bool cold)
                                 if (zone)
                                         spin_unlock_irqrestore(&zone->lru_lock,
                                                                         flags);
+                                lock_batch = 0;
                                 zone = pagezone;
                                 spin_lock_irqsave(&zone->lru_lock, flags);
                         }