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=-2.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 49FF0FA372A for ; Wed, 16 Oct 2019 14:33:09 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A88832067D for ; Wed, 16 Oct 2019 14:33:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="c+MkPeid" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A88832067D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=rYOSWYy7ocBBh7+/6lh5Rn0DogWc8kFqkgPm8TP+5+Y=; b=c+MkPeidUaD3qp /f4CPZL25ds4+daOzL+ct10zfhdI0LvOnouNmsFzC53njHJs7SvHv0TuB744+H61FRerZMT4c+HI+ GL4AR9/luhNlhZ1gk1pGif0LwZO/UBTAqthW0LzvejrSCMQ7zgVzQ8gsHwBfI0Z9iIb2oBs998Wiv NG5vG8fBEMSJZUk5kbkiKOtJFIwjmg8fDxGtvMxGYaXKLPoK6LKatAA6dT9rTFaBXqD2oqNWPnZuz 7fPxAvjFlTReRYLkuEQnzCkCqkbdi+f98A7guIaasyQNDL0r1CYNc1kvcnCGWLolN8jDFCWkNQwWd Vifu6R3OFUky/RZw2gIg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iKkMI-00006m-S2; Wed, 16 Oct 2019 14:33:02 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iKkMG-00005W-0j for linux-arm-kernel@lists.infradead.org; Wed, 16 Oct 2019 14:33:01 +0000 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 2492D142F; Wed, 16 Oct 2019 07:32:57 -0700 (PDT) Received: from arrakis.emea.arm.com (unknown [10.1.196.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7C5453F68E; Wed, 16 Oct 2019 07:32:54 -0700 (PDT) Date: Wed, 16 Oct 2019 15:32:52 +0100 From: Catalin Marinas To: Will Deacon Subject: Re: [PATCH v12 0/4] fix double page fault in cow_user_page for pfn mapping Message-ID: <20191016143252.GJ49619@arrakis.emea.arm.com> References: <20191011140939.6115-1-justin.he@arm.com> <20191015001834.wwkd46t6dwicta7n@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191015001834.wwkd46t6dwicta7n@willie-the-truck> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191016_073300_103586_6C6404D8 X-CRM114-Status: GOOD ( 15.51 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Kaly Xin , Jia He , Suzuki Poulose , Marc Zyngier , x86@kernel.org, hejianet@gmail.com, linux-kernel@vger.kernel.org, Matthew Wilcox , linux-mm@kvack.org, James Morse , linux-arm-kernel@lists.infradead.org, "H. Peter Anvin" , Borislav Petkov , Thomas Gleixner , nd@arm.com, Andrew Morton , "Kirill A. Shutemov" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Oct 15, 2019 at 01:18:34AM +0100, Will Deacon wrote: > On Fri, Oct 11, 2019 at 10:09:35PM +0800, Jia He wrote: > > When we tested pmdk unit test vmmalloc_fork TEST1 in arm64 guest, there > > will be a double page fault in __copy_from_user_inatomic of cow_user_page. > > > > As told by Catalin: "On arm64 without hardware Access Flag, copying from > > user will fail because 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 hardware-managed access flag on arm64." > > > > -Changes > > v12: > > refine PATCH 01, remove the !! since C languages can convert unsigned > > to bool (Catalin) > > Thanks. I think it's a bit late to take something like this for 5.4 now, > especially as the current behaviour has always been there. Hopefully > somebody can queue it for 5.5 instead. I can queue this through the arm64 tree for 5.5 if I get an ack on the x86 patch (3/4) or I don't hear any complaints. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel