From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S939220AbdD0Nfe (ORCPT ); Thu, 27 Apr 2017 09:35:34 -0400 Received: from mx2.suse.de ([195.135.220.15]:34660 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1162483AbdD0Nf1 (ORCPT ); Thu, 27 Apr 2017 09:35:27 -0400 Date: Thu, 27 Apr 2017 15:35:23 +0200 From: Michal Hocko To: Igor Stoppa , Andrew Morton Cc: namhyung@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: Question on ___GFP_NOLOCKDEP - Was: Re: [PATCH 1/1] Remove hardcoding of ___GFP_xxx bitmasks Message-ID: <20170427133523.GG4706@dhcp22.suse.cz> References: <20170426133549.22603-1-igor.stoppa@huawei.com> <20170426133549.22603-2-igor.stoppa@huawei.com> <20170426144750.GH12504@dhcp22.suse.cz> <9929419e-c22e-2a9f-a8a6-ad98d5a9da06@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9929419e-c22e-2a9f-a8a6-ad98d5a9da06@huawei.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 27-04-17 15:16:47, Igor Stoppa wrote: > On 26/04/17 18:29, Igor Stoppa wrote: > > > On 26/04/17 17:47, Michal Hocko wrote: > > [...] > > >> Also the current mm tree has ___GFP_NOLOCKDEP which is not addressed > >> here so I suspect you have based your change on the Linus tree. > > > I used your tree from kernel.org > > I found it, I was using master, instead of auto-latest (is it correct?) yes > But now I see something that I do not understand (apologies if I'm > asking something obvious). > > First there is: > > [...] > #define ___GFP_WRITE 0x800000u > #define ___GFP_KSWAPD_RECLAIM 0x1000000u > #ifdef CONFIG_LOCKDEP > #define ___GFP_NOLOCKDEP 0x4000000u > #else > #define ___GFP_NOLOCKDEP 0 > #endif > > Then: > > /* Room for N __GFP_FOO bits */ > #define __GFP_BITS_SHIFT (25 + IS_ENABLED(CONFIG_LOCKDEP)) > > > > Shouldn't it be either: > ___GFP_NOLOCKDEP 0x2000000u Yes it should. At the time when this patch was written this value was used. Later I've removed __GFP_OTHER by 41b6167e8f74 ("mm: get rid of __GFP_OTHER_NODE") and forgot to refresh this one. Thanks for noticing this. Andrew, could you fold the following in please? --- >>From 8dc9c917af215f659bb990fa48ae7b4753027c19 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Thu, 27 Apr 2017 15:28:10 +0200 Subject: [PATCH] lockdep-allow-to-disable-reclaim-lockup-detection-fix Igor Stoppa has noticed that __GFP_NOLOCKDEP can use a lower bit. At the time lockdep-allow-to-disable-reclaim-lockup-detection was written we still had __GFP_OTHER_NODE but I have removed it in 41b6167e8f74 ("mm: get rid of __GFP_OTHER_NODE") and forgot to lower the bit value. Signed-off-by: Michal Hocko --- include/linux/gfp.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 2b1a44f5bdb6..a89d37e8b387 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -41,7 +41,7 @@ struct vm_area_struct; #define ___GFP_WRITE 0x800000u #define ___GFP_KSWAPD_RECLAIM 0x1000000u #ifdef CONFIG_LOCKDEP -#define ___GFP_NOLOCKDEP 0x4000000u +#define ___GFP_NOLOCKDEP 0x2000000u #else #define ___GFP_NOLOCKDEP 0 #endif -- 2.11.0 -- Michal Hocko SUSE Labs