From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757459Ab2CZN4O (ORCPT ); Mon, 26 Mar 2012 09:56:14 -0400 Received: from gir.skynet.ie ([193.1.99.77]:50875 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757383Ab2CZN4N (ORCPT ); Mon, 26 Mar 2012 09:56:13 -0400 Date: Mon, 26 Mar 2012 14:56:09 +0100 From: Mel Gorman To: Pekka Enberg Cc: Rik van Riel , Anton Blanchard , aarcange@redhat.com, akpm@linux-foundation.org, hughd@google.com, lkml , linux-mm@kvack.org, Linus Torvalds Subject: Re: [PATCH] Re: kswapd stuck using 100% CPU Message-ID: <20120326135609.GM1007@csn.ul.ie> References: <20120324130353.48f2e4c8@kryten> <20120324102621.353114da@annuminas.surriel.com> <20120326093201.GL1007@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 26, 2012 at 01:40:41PM +0300, Pekka Enberg wrote: > On Mon, Mar 26, 2012 at 12:32 PM, Mel Gorman wrote: > > On Sat, Mar 24, 2012 at 10:26:21AM -0400, Rik van Riel wrote: > >> > >> 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. > >> > >> Signed-off-by: Rik van Riel > >> Reported-by: Anton Blanchard > > > > Acked-by: Mel Gorman > > The API looks fragile and this patch isn't exactly making it any > better. Why don't we make compaction_suitable() return something other > than COMPACT_SKIPPED for !CONFIG_COMPACTION case? > Returning COMPACT_PARTIAL or COMPACT_CONTINUE would confuse the check in should_continue_reclaim. A fourth return type could be added but an obvious name does not spring to mind that would end up being similar to just adding a CONFIG_COMPACTION check. -- Mel Gorman SUSE Labs