From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f197.google.com (mail-pf1-f197.google.com [209.85.210.197]) by kanga.kvack.org (Postfix) with ESMTP id 1AE816B0289 for ; Thu, 25 Oct 2018 06:47:10 -0400 (EDT) Received: by mail-pf1-f197.google.com with SMTP id v88-v6so6188919pfk.19 for ; Thu, 25 Oct 2018 03:47:10 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id bj11-v6sor6148749plb.16.2018.10.25.03.47.08 for (Google Transport Security); Thu, 25 Oct 2018 03:47:08 -0700 (PDT) Date: Thu, 25 Oct 2018 13:47:03 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCH 1/4] treewide: remove unused address argument from pte_alloc functions (v2) Message-ID: <20181025104703.esl6wxyg2ihe4zoc@kshutemo-mobl1> References: <20181013013200.206928-1-joel@joelfernandes.org> <20181013013200.206928-2-joel@joelfernandes.org> <20181024083716.GN3109@worktop.c.hoisthospitality.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181024083716.GN3109@worktop.c.hoisthospitality.com> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: "Joel Fernandes (Google)" , linux-kernel@vger.kernel.org, kernel-team@android.com, Michal Hocko , Julia Lawall , akpm@linux-foundation.org, Andrey Ryabinin , Andy Lutomirski , anton.ivanov@kot-begemot.co.uk, Borislav Petkov , Catalin Marinas , Chris Zankel , dancol@google.com, Dave Hansen , "David S. Miller" , elfring@users.sourceforge.net, Fenghua Yu , Geert Uytterhoeven , Guan Xuetao , Helge Deller , hughd@google.com, Ingo Molnar , "James E.J. Bottomley" , Jeff Dike , Jonas Bonn , kasan-dev@googlegroups.com, kvmarm@lists.cs.columbia.edu, Ley Foon Tan , linux-alpha@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@linux-mips.org, linux-mm@kvack.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, lokeshgidra@google.com, Max Filippov , minchan@kernel.org, nios2-dev@lists.rocketboards.org, pantin@google.com, Richard Weinberger , Rich Felker , Sam Creasey , sparclinux@vger.kernel.org, Stafford Horne , Stefan Kristiansson , Thomas Gleixner , Tony Luck , Will Deacon , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Yoshinori Sato On Wed, Oct 24, 2018 at 10:37:16AM +0200, Peter Zijlstra wrote: > On Fri, Oct 12, 2018 at 06:31:57PM -0700, Joel Fernandes (Google) wrote: > > This series speeds up mremap(2) syscall by copying page tables at the > > PMD level even for non-THP systems. There is concern that the extra > > 'address' argument that mremap passes to pte_alloc may do something > > subtle architecture related in the future that may make the scheme not > > work. Also we find that there is no point in passing the 'address' to > > pte_alloc since its unused. So this patch therefore removes this > > argument tree-wide resulting in a nice negative diff as well. Also > > ensuring along the way that the enabled architectures do not do anything > > funky with 'address' argument that goes unnoticed by the optimization. > > Did you happen to look at the history of where that address argument > came from? -- just being curious here. ISTR something vague about > architectures having different paging structure for different memory > ranges. I see some archicetures (i.e. sparc and, I believe power) used the address for coloring. It's not needed anymore. Page allocator and SL?B are good enough now. See 3c936465249f ("[SPARC64]: Kill pgtable quicklists and use SLAB.") -- Kirill A. Shutemov