Merge branch 'master' into for-next

1 files changed, 16 insertions, 6 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 612a7c9795f6..4a7f7e6992b6 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -616,7 +616,7 @@ scan:
 		}
 	}
 	offset = si->lowest_bit;
-	while (++offset < scan_base) {
+	while (offset < scan_base) {
 		if (!si->swap_map[offset]) {
 			spin_lock(&si->lock);
 			goto checks;
@@ -629,6 +629,7 @@ scan:
 			cond_resched();
 			latency_ration = LATENCY_LIMIT;
 		}
+		offset++;
 	}
 	spin_lock(&si->lock);
 
@@ -906,7 +907,7 @@ int reuse_swap_page(struct page *page)
 {
 	int count;
 
-	VM_BUG_ON(!PageLocked(page));
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	if (unlikely(PageKsm(page)))
 		return 0;
 	count = page_mapcount(page);
@@ -926,7 +927,7 @@ int reuse_swap_page(struct page *page)
  */
 int try_to_free_swap(struct page *page)
 {
-	VM_BUG_ON(!PageLocked(page));
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
 
 	if (!PageSwapCache(page))
 		return 0;
@@ -1922,7 +1923,6 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 	p->swap_map = NULL;
 	cluster_info = p->cluster_info;
 	p->cluster_info = NULL;
-	p->flags = 0;
 	frontswap_map = frontswap_map_get(p);
 	spin_unlock(&p->lock);
 	spin_unlock(&swap_lock);
@@ -1948,6 +1948,16 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
 		mutex_unlock(&inode->i_mutex);
 	}
 	filp_close(swap_file, NULL);
+
+	/*
+	 * Clear the SWP_USED flag after all resources are freed so that swapon
+	 * can reuse this swap_info in alloc_swap_info() safely.  It is ok to
+	 * not hold p->lock after we cleared its SWP_WRITEOK.
+	 */
+	spin_lock(&swap_lock);
+	p->flags = 0;
+	spin_unlock(&swap_lock);
+
 	err = 0;
 	atomic_inc(&proc_poll_event);
 	wake_up_interruptible(&proc_poll_wait);
@@ -2714,7 +2724,7 @@ struct swap_info_struct *page_swap_info(struct page *page)
  */
 struct address_space *__page_file_mapping(struct page *page)
 {
-	VM_BUG_ON(!PageSwapCache(page));
+	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
 	return page_swap_info(page)->swap_file->f_mapping;
 }
 EXPORT_SYMBOL_GPL(__page_file_mapping);
@@ -2722,7 +2732,7 @@ EXPORT_SYMBOL_GPL(__page_file_mapping);
 pgoff_t __page_file_index(struct page *page)
 {
 	swp_entry_t swap = { .val = page_private(page) };
-	VM_BUG_ON(!PageSwapCache(page));
+	VM_BUG_ON_PAGE(!PageSwapCache(page), page);
 	return swp_offset(swap);
 }
 EXPORT_SYMBOL_GPL(__page_file_index);