From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750949AbdJBH3H (ORCPT ); Mon, 2 Oct 2017 03:29:07 -0400 Received: from mx2.suse.de ([195.135.220.15]:57878 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750715AbdJBH3G (ORCPT ); Mon, 2 Oct 2017 03:29:06 -0400 Date: Mon, 2 Oct 2017 09:29:04 +0200 From: Michal Hocko To: "Levin, Alexander (Sasha Levin)" Cc: Vegard Nossum , Steven Rostedt , "akpm@linux-foundation.org" , "linux-kernel@vger.kernel.org" , "David S . Miller" , Alexander Potapenko , Andrey Ryabinin , Dmitry Vyukov Subject: Re: [PATCH] mm: kill kmemcheck again Message-ID: <20171002072904.cpfp6gkaakag7icm@dhcp22.suse.cz> References: <20170927112723.16862-1-alexander.levin@verizon.com> <20170927150207.swmcarc4lqlklohr@dhcp22.suse.cz> <20170930054815.0e2c182f@vmware.local.home> <20170930200239.ngcyp2tcpuidpctv@sasha-lappy> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170930200239.ngcyp2tcpuidpctv@sasha-lappy> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat 30-09-17 20:02:41, Sasha Levin wrote: > On Sat, Sep 30, 2017 at 03:57:27PM +0200, Vegard Nossum wrote: > >On 30 September 2017 at 11:48, Steven Rostedt wrote: > >> On Wed, 27 Sep 2017 17:02:07 +0200 > >> Michal Hocko wrote: > >> > >>> > Now that 2 years have passed, and all distros provide gcc that supports > >>> > KASAN, kill kmemcheck again for the very same reasons. > >>> > >>> This is just too large to review manually. How have you generated the > >>> patch? > >> > >> I agree. This needs to be taken out piece by piece, not in one go, > >> where there could be unexpected fallout. > > > >I have a patch from earlier this year that starts by removing the core > >code and defining all the helpers/flags as no-ops so they can be > >removed bit by bit at a later time. See the attachment. Pekka signed > >off on it too. > >e > >I never actually submitted this because I was waiting for MSAN to be > > I'm not sure how much value there is in doing it this way. I agree > that the patch is big, but most of it is simply removing code under > arch/x86/mm/kmemcheck. > > The difference between Vegard's patch and mine is about 300 lines > (out of 2800+), where those 300 lines are simply removing calls to > kmemcheck. There are no logic changes. (so something very similar to > 's/*kmemcheck*//g' would do the trick). Maybe splitting the patch into three: 1) remove all callers of kmemleak API and 2) remove arch/x86/mm/kmemcheck/ and 3) remove leftovers would be slightly easier to review. Maybe 2 and 3 would have some dependencies so they would have to end up in the same path. Just my 2c -- Michal Hocko SUSE Labs