From: Rik van Riel <riel@redhat.com>
Date: Sat, 24 Mar 2012 14:26:21 +0000 (-0400)
Subject: Fix potential endless loop in kswapd when compaction is not enabled
X-Git-Tag: v3.4-rc1~95
X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=496b919b3bdd957d4b1727df79bfa3751bced1c1;p=~emulex%2Finfiniband.git

Fix potential endless loop in kswapd when compaction is not enabled

We should only test compaction_suitable if the kernel is built with
CONFIG_COMPACTION, otherwise the stub compaction_suitable function will
always return COMPACT_SKIPPED and send kswapd into an infinite loop.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7658fd6536d..33c332bbab7 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2946,7 +2946,8 @@ out:
 				continue;
 
 			/* Would compaction fail due to lack of free memory? */
-			if (compaction_suitable(zone, order) == COMPACT_SKIPPED)
+			if (COMPACTION_BUILD &&
+			    compaction_suitable(zone, order) == COMPACT_SKIPPED)
 				goto loop_again;
 
 			/* Confirm the zone is balanced for order-0 */