From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id D339E6B007E for ; Wed, 20 Jul 2011 01:44:22 -0400 (EDT) Received: by mail-qw0-f41.google.com with SMTP id 26so3394345qwa.14 for ; Tue, 19 Jul 2011 22:44:21 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1311059367.15392.299.camel@sli10-conroe> References: <1311059367.15392.299.camel@sli10-conroe> Date: Wed, 20 Jul 2011 14:44:21 +0900 Message-ID: Subject: Re: [PATCH]vmscan: fix a livelock in kswapd From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Shaohua Li Cc: Andrew Morton , mgorman@suse.de, linux-mm , lkml On Tue, Jul 19, 2011 at 4:09 PM, Shaohua Li wrote: > I'm running a workload which triggers a lot of swap in a machine with 4 nodes. > After I kill the workload, I found a kswapd livelock. Sometimes kswapd3 or > kswapd2 are keeping running and I can't access filesystem, but most memory is > free. This looks like a regression since commit 08951e545918c159. > Node 2 and 3 have only ZONE_NORMAL, but balance_pgdat() will return 0 for > classzone_idx. The reason is end_zone in balance_pgdat() is 0 by default, if > all zones have watermark ok, end_zone will keep 0. > Later sleeping_prematurely() always returns true. Because this is an order 3 > wakeup, and if classzone_idx is 0, both balanced_pages and present_pages > in pgdat_balanced() are 0. > We add a special case here. If a zone has no page, we think it's balanced. This > fixes the livelock. > > Signed-off-by: Shaohua Li Reviewed-by: Minchan Kim -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org