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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 48780C43603 for ; Mon, 9 Dec 2019 20:24:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2130B2068E for ; Mon, 9 Dec 2019 20:24:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726675AbfLIUYy (ORCPT ); Mon, 9 Dec 2019 15:24:54 -0500 Received: from ale.deltatee.com ([207.54.116.67]:58624 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726495AbfLIUYx (ORCPT ); Mon, 9 Dec 2019 15:24:53 -0500 Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtp (Exim 4.92) (envelope-from ) id 1iePa0-0003kM-0J; Mon, 09 Dec 2019 13:24:29 -0700 To: David Hildenbrand , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig , Dan Williams , Andrew Morton Cc: Catalin Marinas , Will Deacon , Benjamin Herrenschmidt , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Michal Hocko References: <20191209191346.5197-1-logang@deltatee.com> <20191209191346.5197-6-logang@deltatee.com> From: Logan Gunthorpe Message-ID: Date: Mon, 9 Dec 2019 13:24:19 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Language: en-CA Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: mhocko@suse.com, peterz@infradead.org, luto@kernel.org, dave.hansen@linux.intel.com, bp@alien8.de, mingo@redhat.com, tglx@linutronix.de, benh@kernel.crashing.org, will@kernel.org, catalin.marinas@arm.com, akpm@linux-foundation.org, dan.j.williams@intel.com, hch@lst.de, linux-mm@kvack.org, platform-driver-x86@vger.kernel.org, linux-sh@vger.kernel.org, linux-s390@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-ia64@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, david@redhat.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH 5/6] mm, memory_hotplug: Provide argument for the pgprot_t in arch_add_memory() X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-12-09 12:23 p.m., David Hildenbrand wrote: > On 09.12.19 20:13, Logan Gunthorpe wrote: >> devm_memremap_pages() is currently used by the PCI P2PDMA code to create >> struct page mappings for IO memory. At present, these mappings are created >> with PAGE_KERNEL which implies setting the PAT bits to be WB. However, on >> x86, an mtrr register will typically override this and force the cache >> type to be UC-. In the case firmware doesn't set this register it is >> effectively WB and will typically result in a machine check exception >> when it's accessed. >> >> Other arches are not currently likely to function correctly seeing they >> don't have any MTRR registers to fall back on. >> >> To solve this, add an argument to arch_add_memory() to explicitly >> set the pgprot value to a specific value. >> >> Of the arches that support MEMORY_HOTPLUG: x86_64, s390 and arm64 is a >> simple change to pass the pgprot_t down to their respective functions >> which set up the page tables. For x86_32, set the page tables explicitly >> using _set_memory_prot() (seeing they are already mapped). For sh, reject >> anything but PAGE_KERNEL settings -- this should be fine, for now, seeing >> sh doesn't support ZONE_DEVICE anyway. >> >> Cc: Dan Williams >> Cc: David Hildenbrand >> Cc: Michal Hocko >> Signed-off-by: Logan Gunthorpe >> --- >> arch/arm64/mm/mmu.c | 4 ++-- >> arch/ia64/mm/init.c | 5 ++++- >> arch/powerpc/mm/mem.c | 4 ++-- >> arch/s390/mm/init.c | 4 ++-- >> arch/sh/mm/init.c | 5 ++++- >> arch/x86/mm/init_32.c | 7 ++++++- >> arch/x86/mm/init_64.c | 4 ++-- >> include/linux/memory_hotplug.h | 2 +- >> mm/memory_hotplug.c | 2 +- >> mm/memremap.c | 2 +- >> 10 files changed, 25 insertions(+), 14 deletions(-) >> >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 60c929f3683b..48b65272df15 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -1050,7 +1050,7 @@ int p4d_free_pud_page(p4d_t *p4d, unsigned long addr) >> } >> >> #ifdef CONFIG_MEMORY_HOTPLUG >> -int arch_add_memory(int nid, u64 start, u64 size, >> +int arch_add_memory(int nid, u64 start, u64 size, pgprot_t prot, >> struct mhp_restrictions *restrictions) > > Can we fiddle that into "struct mhp_restrictions" instead? Yes, if that's what people want, it's pretty trivial to do. I chose not to do it that way because it doesn't get passed down to add_pages() and it's not really a "restriction". If I don't hear any objections, I will do that for v2. Thanks, Logan