From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f44.google.com (mail-qg0-f44.google.com [209.85.192.44]) by kanga.kvack.org (Postfix) with ESMTP id B9BFA6B0098 for ; Tue, 27 May 2014 10:21:39 -0400 (EDT) Received: by mail-qg0-f44.google.com with SMTP id i50so13791804qgf.17 for ; Tue, 27 May 2014 07:21:39 -0700 (PDT) Received: from qmta03.emeryville.ca.mail.comcast.net (qmta03.emeryville.ca.mail.comcast.net. [2001:558:fe2d:43:76:96:30:32]) by mx.google.com with ESMTP id q16si17491229qay.123.2014.05.27.07.21.38 for ; Tue, 27 May 2014 07:21:39 -0700 (PDT) Date: Tue, 27 May 2014 09:21:32 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH] page_alloc: skip cpuset enforcement for lower zone allocations In-Reply-To: <20140523193706.GA22854@amt.cnet> Message-ID: References: <20140523193706.GA22854@amt.cnet> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Marcelo Tosatti Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Lai Jiangshan , Mel Gorman , Tejun Heo , David Rientjes , Andrew Morton On Fri, 23 May 2014, Marcelo Tosatti wrote: > Zone specific allocations, such as GFP_DMA32, should not be restricted > to cpusets allowed node list: the zones which such allocations demand > might be contained in particular nodes outside the cpuset node list. > > The alternative would be to not perform such allocations from > applications which are cpuset restricted, which is unrealistic. > > Fixes KVM's alloc_page(gfp_mask=GFP_DMA32) with cpuset as explained. Memory policies are only applied to a specific zone so this is not unprecedented. However, if a user wants to limit allocation to a specific node and there is no DMA memory there then may be that is a operator error? After all the application will be using memory from a node that the operator explicitly wanted not to be used. There is also the hardwall flag. I think its ok to allocate outside of the cpuset if that flag is not set. However, if it is set then any attempt to alloc outside of the cpuset should fail. -- 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/ . Don't email: email@kvack.org