[PATCH] rmap bugfix, try_to_unmap

[Rik van Riel]

Hi,

the following patch corrects a bug where rmap would continue
trying to swap out a page even after it failed on one pte,
which could result in leaked pte chains and a bug when exiting
applications which use mlock().

The bug was tracked down by Christian Ehrhardt, the reason
it wasn't found earlier was a subtlety in the code, so I've
taken the liberty of changing Christian's patch into something
more explicit, we shouldn't let this one happen again ;)

please apply,

Rik
-- 
Bravely reimplemented by the knights who say "NIH".

http://www.surriel.com/		http://distro.conectiva.com/

===== mm/rmap.c 1.7 vs edited =====
--- 1.7/mm/rmap.c	Wed Jul 31 06:58:53 2002
+++ edited/mm/rmap.c	Mon Aug 12 11:22:05 2002
@@ -328,7 +328,7 @@
 				case SWAP_SUCCESS:
 					/* Free the pte_chain struct. */
 					pte_chain_free(pc, prev_pc, page);
-					break;
+					continue;
 				case SWAP_AGAIN:
 					/* Skip this pte, remembering status. */
 					prev_pc = pc;
@@ -336,12 +336,13 @@
 					continue;
 				case SWAP_FAIL:
 					ret = SWAP_FAIL;
-					break;
+					goto give_up;
 				case SWAP_ERROR:
 					ret = SWAP_ERROR;
-					break;
+					goto give_up;
 			}
 		}
+give_up:
 		/* Check whether we can convert to direct pte pointer */
 		pc = page->pte.chain;
 		if (pc && !pc->next) {