Re: set_page_dirty/page_launder deadlock

[David S. Miller]

Marcelo Tosatti writes:
 > 
 > While taking a look at page_launder()...

 ...

 > set_page_dirty() may lock the pagecache_lock which means potential
 > deadlock since we have the pagemap_lru_lock locked.

Indeed, the following should work as a fix:

--- mm/vmscan.c.~1~	Thu Jan 11 02:22:19 2001
+++ mm/vmscan.c	Sun Jan 14 05:26:17 2001
@@ -493,12 +493,15 @@
 			page_cache_release(page);
 
 			/* And re-start the thing.. */
-			spin_lock(&pagemap_lru_lock);
-			if (result != 1)
+			if (result != 1) {
+				spin_lock(&pagemap_lru_lock);
 				continue;
-			/* writepage refused to do anything */
-			set_page_dirty(page);
-			goto page_active;
+			} else {
+				/* writepage refused to do anything */
+				set_page_dirty(page);
+				spin_lock(&pagemap_lru_lock);
+				goto page_active;
+			}
 		}
 
 		/*