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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 D02FFC4CECF for ; Mon, 23 Sep 2019 16:18:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9CAC32168B for ; Mon, 23 Sep 2019 16:18:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388889AbfIWQSb (ORCPT ); Mon, 23 Sep 2019 12:18:31 -0400 Received: from foss.arm.com ([217.140.110.172]:45108 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387827AbfIWQSa (ORCPT ); Mon, 23 Sep 2019 12:18:30 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E50011000; Mon, 23 Sep 2019 09:18:29 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 404EF3F67D; Mon, 23 Sep 2019 09:18:27 -0700 (PDT) Date: Mon, 23 Sep 2019 17:18:25 +0100 From: Catalin Marinas To: Jia He Cc: Will Deacon , Mark Rutland , James Morse , Marc Zyngier , Matthew Wilcox , "Kirill A. Shutemov" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suzuki Poulose , Punit Agrawal , Anshuman Khandual , Alex Van Brunt , Robin Murphy , Thomas Gleixner , Andrew Morton , =?iso-8859-1?B?Suly9G1l?= Glisse , Ralph Campbell , hejianet@gmail.com, Kaly Xin , nd@arm.com Subject: Re: [PATCH v8 2/3] arm64: mm: implement arch_faults_on_old_pte() on arm64 Message-ID: <20190923161824.GD10192@arrakis.emea.arm.com> References: <20190921135054.142360-1-justin.he@arm.com> <20190921135054.142360-3-justin.he@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190921135054.142360-3-justin.he@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 21, 2019 at 09:50:53PM +0800, Jia He wrote: > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index e09760ece844..4a9939615e41 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -868,6 +868,18 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, > #define phys_to_ttbr(addr) (addr) > #endif > > +/* > + * On arm64 without hardware Access Flag, copying fromuser will fail because ^^^^^^^^ from user > + * the pte is old and cannot be marked young. So we always end up with zeroed > + * page after fork() + CoW for pfn mappings. we don't always have a ^^ We > + * hardware-managed access flag on arm64. > + */ > +static inline bool arch_faults_on_old_pte(void) > +{ > + return !cpu_has_hw_af(); I saw an early incarnation of your patch having a WARN_ON(preemptible()). I think we need this back just in case this function will be used elsewhere in the future. > +} > +#define arch_faults_on_old_pte arch_faults_on_old_pte Otherwise, Reviewed-by: Catalin Marinas