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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 C5218C43331 for ; Wed, 25 Mar 2020 11:23:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A286A20771 for ; Wed, 25 Mar 2020 11:23:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727388AbgCYLXO (ORCPT ); Wed, 25 Mar 2020 07:23:14 -0400 Received: from foss.arm.com ([217.140.110.172]:46892 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727082AbgCYLXO (ORCPT ); Wed, 25 Mar 2020 07:23:14 -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 BD5D931B; Wed, 25 Mar 2020 04:23:13 -0700 (PDT) Received: from mbp (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E68463F71F; Wed, 25 Mar 2020 04:23:12 -0700 (PDT) Date: Wed, 25 Mar 2020 11:23:10 +0000 From: Catalin Marinas To: Will Deacon Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@android.com, Linus Torvalds Subject: Re: [PATCH] mm/mremap: Add comment explaining the untagging behaviour of mremap() Message-ID: <20200325112309.GM3901@mbp> References: <20200325111347.32553-1-will@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200325111347.32553-1-will@kernel.org> 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 Wed, Mar 25, 2020 at 11:13:46AM +0000, Will Deacon wrote: > Commit dcde237319e6 ("mm: Avoid creating virtual address aliases in > brk()/mmap()/mremap()") changed mremap() so that only the 'old' address > is untagged, leaving the 'new' address in the form it was passed from > userspace. This prevents the unexpected creation of aliasing virtual > mappings in userspace, but looks a bit odd when you read the code. > > Add a comment justifying the untagging behaviour in mremap(). > > Cc: Catalin Marinas > Reported-by: Linus Torvalds > Signed-off-by: Will Deacon Reviewed-by: Catalin Marinas 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=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 A14D6C43331 for ; Wed, 25 Mar 2020 11:23:23 +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 6E2D920771 for ; Wed, 25 Mar 2020 11:23:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="hqvQAvQR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6E2D920771 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=RxMfp7UB1Leh/t4Q6qeyKK+G4Sg4yr5yXKm+3ZED/8I=; b=hqvQAvQRpR881y 4VvqQ+M9CiSRRA9U06fxchGONtCSeztzqfZQRXlFxDfpQ0aHz9+A+8Bmejn0HAYacGrUiZh5AxVkP fApuVcU1KMlRCaefqLKGjMAcIV2HJsExscWN3Yzrj56xTeGtkcJ1N7wN4PauVpHDS6orW1+BEHUUp UhqJ6qbzEJErnoLNB9QcZRephfOM5AvpN1XYfAxQ/lQ6S0MoF4KnAWh7TH+qTMR8PdR/cJY5e/f0r xTu3x5tnU26Exf6Qc8hqJ8xTNpOgIeYg4hGe4tyX2PhibxABUWLA3xlc/YsdEZSI3DGCapT3TPSjy Kra3h8WDXNzw+NS7/dkA==; 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 1jH482-0001gu-TY; Wed, 25 Mar 2020 11:23:22 +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 1jH47v-0001fz-A2 for linux-arm-kernel@lists.infradead.org; Wed, 25 Mar 2020 11:23:22 +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 BD5D931B; Wed, 25 Mar 2020 04:23:13 -0700 (PDT) Received: from mbp (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E68463F71F; Wed, 25 Mar 2020 04:23:12 -0700 (PDT) Date: Wed, 25 Mar 2020 11:23:10 +0000 From: Catalin Marinas To: Will Deacon Subject: Re: [PATCH] mm/mremap: Add comment explaining the untagging behaviour of mremap() Message-ID: <20200325112309.GM3901@mbp> References: <20200325111347.32553-1-will@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200325111347.32553-1-will@kernel.org> 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-20200325_042315_398901_4A2234CA X-CRM114-Status: GOOD ( 10.40 ) 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: Linus Torvalds , kernel-team@android.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org 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 Wed, Mar 25, 2020 at 11:13:46AM +0000, Will Deacon wrote: > Commit dcde237319e6 ("mm: Avoid creating virtual address aliases in > brk()/mmap()/mremap()") changed mremap() so that only the 'old' address > is untagged, leaving the 'new' address in the form it was passed from > userspace. This prevents the unexpected creation of aliasing virtual > mappings in userspace, but looks a bit odd when you read the code. > > Add a comment justifying the untagging behaviour in mremap(). > > Cc: Catalin Marinas > Reported-by: Linus Torvalds > Signed-off-by: Will Deacon Reviewed-by: Catalin Marinas _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel