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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 AD93CC47254 for ; Mon, 4 May 2020 05:04:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8FED3206EB for ; Mon, 4 May 2020 05:04:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726906AbgEDFEv (ORCPT ); Mon, 4 May 2020 01:04:51 -0400 Received: from mga12.intel.com ([192.55.52.136]:43373 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725894AbgEDFEu (ORCPT ); Mon, 4 May 2020 01:04:50 -0400 IronPort-SDR: RI4gvK+9HDVAKbRklvMRzIq+pixxdYwbvyTVuNGFD83c+J+nmEf9PVYs8K3ZAJRRWmwQxHCADe 82/fHngT1KIw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 May 2020 22:04:49 -0700 IronPort-SDR: MxCGejezytWAFr2qtWtnEu9Zlbx9sDBny4KBWGPuntnxpb8eeVieC20Y3SJ8U7XteAAgk3t7Pj fSoUNNLnXPgQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,350,1583222400"; d="scan'208";a="295395757" Received: from iweiny-desk2.sc.intel.com ([10.3.52.147]) by orsmga008.jf.intel.com with ESMTP; 03 May 2020 22:04:48 -0700 Date: Sun, 3 May 2020 22:04:47 -0700 From: Ira Weiny To: Al Viro 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: <20200504050447.GA979899@iweiny-DESK2.sc.intel.com> References: <20200504010912.982044-1-ira.weiny@intel.com> <20200504013509.GU23230@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200504013509.GU23230@ZenIV.linux.org.uk> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Mon, May 04, 2020 at 02:35:09AM +0100, Al Viro wrote: > 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. Yes patch 6 makes the change because kmap_atomic() was no longer declared in asm/highmem.h. I'm pretty sure 0-day caught that ... but I seem to remember noticing some oddness in that file and I did go through it by hand. > > * 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'... Easy enough. Added as a follow on patch. > > * 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. Agreed. Done in a follow on patch. > > 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. Grepping for 'asm/highmem.h' and investigations don't reveal any issues... But you do have me worried. That said 0-day has been crunching on multiple versions of this series without issues such as this (save the mips issue above). I have to say it would be nice if the relation between linux/highmem.h and asm/highmem.h was more straightforward. Ira