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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 24D6AC433E3 for ; Fri, 17 Jul 2020 09:20:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F278B20691 for ; Fri, 17 Jul 2020 09:20:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="AEJQmWGi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726079AbgGQJUZ (ORCPT ); Fri, 17 Jul 2020 05:20:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52796 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725932AbgGQJUY (ORCPT ); Fri, 17 Jul 2020 05:20:24 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B1FBC061755; Fri, 17 Jul 2020 02:20:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=vD7ogw/DhcHODHv2SCgzRx5wCV73axCwV9UAHq/1Hbs=; b=AEJQmWGipvhnfI6mCc6xEM/Rt1 P3GrZ7sBFk0hlBFp137PYFnvWOJGZNv3bFsNz986Z2rFlhmlsxqsFiuWGdaFXV58Q/0Q1lwLZWhkY tohXqG4s7Guw2+BMyDO6CLmxbq8RVdkl9Uuvsse7QROwJgF8eklcfc38kX9b0GGQ7LUZ4vI4Dbn6x 7n+sL8Wa+yeDoXbuafGGA9MdKyEXEpDIsXCr9cRjsEyjdb5oLGK4REc34sUtyh1ApWgoc5qsynV83 GGvV+NQoh/Ropd/S9sG5wyHDOFNOfzYQZ9l88S2lEIq5poau+tVs1/+tSpgzET+mJwXFSvJfBgWIB fDmu/Ixw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jwMXQ-0002yY-4H; Fri, 17 Jul 2020 09:20:16 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id B7450300446; Fri, 17 Jul 2020 11:20:14 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id A22FF29CF6F51; Fri, 17 Jul 2020 11:20:14 +0200 (CEST) Date: Fri, 17 Jul 2020 11:20:14 +0200 From: Peter Zijlstra To: ira.weiny@intel.com Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , x86@kernel.org, Dave Hansen , Dan Williams , Vishal Verma , Andrew Morton , Fenghua Yu , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC V2 12/17] memremap: Add zone device access protection Message-ID: <20200717092014.GB10769@hirez.programming.kicks-ass.net> References: <20200717072056.73134-1-ira.weiny@intel.com> <20200717072056.73134-13-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200717072056.73134-13-ira.weiny@intel.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Jul 17, 2020 at 12:20:51AM -0700, ira.weiny@intel.com wrote: > From: Ira Weiny > > Device managed memory exposes itself to the kernel direct map which > allows stray pointers to access these device memories. > > Stray pointers to normal memory may result in a crash or other > undesirable behavior which, while unfortunate, are usually recoverable > with a reboot. Stray writes to areas such as non-volatile memory are > permanent in nature and thus are more likely to result in permanent user > data loss vs a stray write to other memory areas > + pks_update_protection(dev_page_pkey, PKEY_DISABLE_ACCESS); So on the one hand you talk about the problem of stray writes, but then you disable all access.