From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6611C28CBC for ; Mon, 4 May 2020 01:35:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9614F206E6 for ; Mon, 4 May 2020 01:35:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726906AbgEDBfY (ORCPT ); Sun, 3 May 2020 21:35:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44922 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726377AbgEDBfY (ORCPT ); Sun, 3 May 2020 21:35:24 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D83FBC061A0E; Sun, 3 May 2020 18:35:23 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jVQ0j-000SR4-3a; Mon, 04 May 2020 01:35:09 +0000 Date: Mon, 4 May 2020 02:35:09 +0100 From: Al Viro To: ira.weiny@intel.com Cc: linux-kernel@vger.kernel.org, Andrew Morton , Christian Koenig , Huang Rui , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Benjamin Herrenschmidt , Paul Mackerras , "David S. Miller" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Chris Zankel , Max Filippov , Dan Williams , linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH V2 00/11] Subject: Remove duplicated kmap code Message-ID: <20200504013509.GU23230@ZenIV.linux.org.uk> References: <20200504010912.982044-1-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200504010912.982044-1-ira.weiny@intel.com> Sender: linux-csky-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Sun, May 03, 2020 at 06:09:01PM -0700, ira.weiny@intel.com wrote: > From: Ira Weiny > > The kmap infrastructure has been copied almost verbatim to every architecture. > This series consolidates obvious duplicated code by defining core functions > which call into the architectures only when needed. > > Some of the k[un]map_atomic() implementations have some similarities but the > similarities were not sufficient to warrant further changes. > > In addition we remove a duplicate implementation of kmap() in DRM. > > Testing was done by 0day to cover all the architectures I can't readily > build/test. OK... Looking through my old notes on kmap unification (this winter, never went anywhere), * arch/mips/mm/cache.c ought to use linux/highmem.h, not asm/highmem.h I suspect that your series doesn't build on some configs there. Hadn't verified that, though. * kmap_atomic_to_page() is dead, but not quite gone - csky and nds32 brought the damn thing back (nds32 - only an extern). It needs killin'... * parisc is (arguably) abusing kunmap()/kunmap_atomic() for cache flushing. Replace the bulk of its highmem.h with #define ARCH_HAS_FLUSH_ON_KUNMAP #define arch_before_kunmap flush_kernel_dcache_page_addr and have default kunmap()/kunmap_atomic() do #ifdef ARCH_HAS_FLUSH_ON_KUNMAP arch_before_kunmap(page_address(page)); #endif and #ifdef ARCH_HAS_FLUSH_ON_KUNMAP arch_before_kunmap(addr); #endif resp. Kills ARCH_HAS_KMAP along with ifdefs on it, makes parisc use somewhat less hacky. I'd suggest checking various configs on mips - that's likely to cause headache. Said that, my analysis of include chains back then is pretty much worthless by now - I really hate the amount of indirect include chains leading to that sucker on some, but not all configs ;-/ IIRC, the proof that everything using kmap*/kunmap* would pull linux/highmem.h regardless of config took several hours of digging, ran for several pages and had been hopelessly brittle. arch/mips/mm/cache.c was the only exception caught by it, but these days there might be more.