From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758651Ab2I1QkF (ORCPT ); Fri, 28 Sep 2012 12:40:05 -0400 Received: from a193-30.smtp-out.amazonses.com ([199.255.193.30]:15704 "EHLO a193-30.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758601Ab2I1QkD (ORCPT ); Fri, 28 Sep 2012 12:40:03 -0400 Date: Fri, 28 Sep 2012 16:40:02 +0000 From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Glauber Costa cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Mel Gorman Subject: Re: [PATCH] make GFP_NOTRACK flag unconditional In-Reply-To: <5065B42F.5010007@parallels.com> Message-ID: <0000013a0dbfc498-6debffd5-cd68-404c-92a4-4f88d40cf41b-000000@email.amazonses.com> References: <1348826194-21781-1-git-send-email-glommer@parallels.com> <0000013a0d475174-343e3b17-6755-42c1-9dae-a9287ad7d403-000000@email.amazonses.com> <5065B42F.5010007@parallels.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SES-Outgoing: 199.255.193.30 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 28 Sep 2012, Glauber Costa wrote: > On 09/28/2012 06:28 PM, Christoph Lameter wrote: > > On Fri, 28 Sep 2012, Glauber Costa wrote: > > > >> There was a general sentiment in a recent discussion (See > >> https://lkml.org/lkml/2012/9/18/258) that the __GFP flags should be > >> defined unconditionally. Currently, the only offender is GFP_NOTRACK, > >> which is conditional to KMEMCHECK. > >> > >> This simple patch makes it unconditional. > > > > __GFP_NOTRACK is only used in context where CONFIG_KMEMCHECK is defined? > > > > If that is not the case then you need to define GFP_NOTRACK and substitute > > it where necessary. > > > > The flag is passed around extensively, but I was imagining the whole > point of that is that having the flag itself is harmless, and will be > ignored by the page allocator ? Looking through it shows almost nothing that is affected. One thing though is that defining __GFP_NOTRACK to 0 eliminates an "or" operation in alloc_slab_page(). That is already on the slob path so I guess that is minimal Acked-by: Christoph Lameter