From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261674AbVCGIKP (ORCPT ); Mon, 7 Mar 2005 03:10:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261678AbVCGIKP (ORCPT ); Mon, 7 Mar 2005 03:10:15 -0500 Received: from smtp202.mail.sc5.yahoo.com ([216.136.129.92]:6510 "HELO smtp202.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S261674AbVCGIKJ (ORCPT ); Mon, 7 Mar 2005 03:10:09 -0500 Message-ID: <422C0C5D.3060404@yahoo.com.au> Date: Mon, 07 Mar 2005 19:10:05 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.5) Gecko/20050105 Debian/1.7.5-1 X-Accept-Language: en MIME-Version: 1.0 To: akpm@osdl.org CC: greg@kroah.com, linux-kernel@vger.kernel.org, Andrea Arcangeli Subject: Re: [patch 2/5] setup_per_zone_lowmem_reserve() oops fix References: <200503042117.j24LHGrx017967@shell0.pdx.osdl.net> In-Reply-To: <200503042117.j24LHGrx017967@shell0.pdx.osdl.net> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org akpm@osdl.org wrote: > If you do 'echo 0 0 > /proc/sys/vm/lowmem_reserve_ratio' the kernel gets a > divide-by-zero. > > Prevent that, and fiddle with some whitespace too. > > Signed-off-by: Andrew Morton Can we instead have a patch that makes the value zero turn off the lowmem reserve entirely if it is set to zero? Just now I was just testing, and found no easy way to do this other than to make the value large enough that the reserve is insignificant. So the loop would be something like: for (idx = j-1; idx >= 0; idx--) { struct zone *lower_zone; lower_zone = pgdat->node_zones + idx; lower_zone->lowmem_reserve[j] = 0; if (sysctl_lowmem_reserve_ratio[idx] > 0) lower_zone->lowmem_reserve[j] = present_pages / sysctl_lowmem_reserve_ratio[idx]; present_pages += lower_zone->present_pages; }