From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752649AbYL3K4A (ORCPT ); Tue, 30 Dec 2008 05:56:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751682AbYL3Kzv (ORCPT ); Tue, 30 Dec 2008 05:55:51 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:42453 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751629AbYL3Kzv (ORCPT ); Tue, 30 Dec 2008 05:55:51 -0500 From: KOSAKI Motohiro To: LKML , linux-mm , Andrew Morton , Nick Piggin , wassim dagash Subject: [PATCH] mm: stop kswapd's infinite loop at high order allocation Cc: kosaki.motohiro@jp.fujitsu.com Message-Id: <20081230195006.1286.KOSAKI.MOTOHIRO@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.42 [ja] Date: Tue, 30 Dec 2008 19:55:47 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ok, wassim confirmed this patch works well. == From: KOSAKI Motohiro Subject: [PATCH] mm: kswapd stop infinite loop at high order allocation Wassim Dagash reported following kswapd infinite loop problem. kswapd runs in some infinite loop trying to swap until order 10 of zone highmem is OK, While zone higmem (as I understand) has nothing to do with contiguous memory (cause there is no 1-1 mapping) which means kswapd will continue to try to balance order 10 of zone highmem forever (or until someone release a very large chunk of highmem). He proposed remove contenious checking on highmem at all. However hugepage on highmem need contenious highmem page. To add infinite loop stopper is simple and good. Reported-by: wassim dagash Signed-off-by: KOSAKI Motohiro --- mm/vmscan.c | 11 +++++++++++ 1 file changed, 11 insertions(+) Index: b/mm/vmscan.c =================================================================== --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1872,6 +1872,17 @@ out: try_to_freeze(); + /* + * When highmem is very fragmented, + * alloc_pages(GFP_KERNEL, very-high-order) can cause + * infinite loop because zone_watermark_ok(highmem) failed. + * However, alloc_pages(GFP_KERNEL..) indicate highmem memory + * continuousness isn't necessary. + * Therefore we don't want contenious check at 2nd loop. + */ + if (nr_reclaimed < SWAP_CLUSTER_MAX) + order = sc.order = 0; + goto loop_again; }