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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 1AC57C54EED for ; Mon, 30 Jan 2023 17:18:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc: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=0I5sjk5UXvrzSsQbaiNeVwd5voRTsUnBihBCapcA+Dg=; b=HEY8tgytYKVXJW s/ZFmzsX3Ed91z2BMyiHfIwwUIWAp0Ux5/KNtlKmXqBBTZo49MdHqiJ3E7eZpTDlgCIoRVv8tN4ST n6sMyZKBD7vRORWUR2wMM/h+vp0vOD+0O7fzUmd+yT8Z6UHNrs0e2oXCYsqAVv7+gorCLsyeWsFvf VDIBbLLrleiR95dQIjdAVdGM/bGxS2y/LCvTAkzQwWY7COwucTAZyBDtqMJDRWW/AGRNWwTyaV3a5 PvlyPcoltp6M1lkbuGyCPMz+QnbRhP0nGvMQHNhn/deHnEyrG+l8VySkb66ZnO1gNb5Mt7fz7czdo 04EKKYkGCkWYNmcMi/ag==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pMXlo-004SZb-4D; Mon, 30 Jan 2023 17:16:40 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pMXl3-004SXd-Ip for linux-arm-kernel@lists.infradead.org; Mon, 30 Jan 2023 17:15:55 +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 2F55B143D; Mon, 30 Jan 2023 02:09:14 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.13.128]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BA7D43F71E; Mon, 30 Jan 2023 02:08:30 -0800 (PST) Date: Mon, 30 Jan 2023 10:08:14 +0000 From: Mark Rutland To: Will Deacon Cc: Anshuman Khandual , linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, Andrew Morton , linux-kernel@vger.kernel.org, Mark Brown , robin.murphy@arm.com Subject: Re: [PATCH V2] arm64/mm: Intercept pfn changes in set_pte_at() Message-ID: References: <20230109052816.405335-1-anshuman.khandual@arm.com> <20230126133321.GB29148@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230130_091553_695425_DCFAF05A X-CRM114-Status: GOOD ( 29.18 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jan 27, 2023 at 03:16:52PM +0000, Mark Rutland wrote: > On Thu, Jan 26, 2023 at 01:33:22PM +0000, Will Deacon wrote: > > On Tue, Jan 24, 2023 at 11:11:49AM +0530, Anshuman Khandual wrote: > > > On 1/9/23 10:58, Anshuman Khandual wrote: > > > > Changing pfn on a user page table mapped entry, without first going through > > > > break-before-make (BBM) procedure is unsafe. This just updates set_pte_at() > > > > to intercept such changes, via an updated pgattr_change_is_safe(). This new > > > > check happens via __check_racy_pte_update(), which has now been renamed as > > > > __check_safe_pte_update(). > > > > > > > > Cc: Catalin Marinas > > > > Cc: Will Deacon > > > > Cc: Mark Rutland > > > > Cc: Andrew Morton > > > > Cc: linux-arm-kernel@lists.infradead.org > > > > Cc: linux-kernel@vger.kernel.org > > > > Signed-off-by: Anshuman Khandual > > > > --- > > > > This applies on v6.2-rc3. This patch had some test time on an internal CI > > > > system without any issues being reported. > > > > > > Gentle ping, any updates on this patch ? Still any concerns ? > > > > I don't think we really got to the bottom of Mark's concerns with > > unreachable ptes on the stack, did we? I also have vague recollections > > of somebody (Robin?) running into issues with the vmap code not honouring > > BBM. > > > > So I think we should confirm/fix the vmap issue before we enable this check > > and also try to get some testing coverage to address Mark's worries. I think > > he has a syzkaller instance set up, so that sound like a good place to > > start. > > I've thrown my Syzkaller instance at this patch; if it doesn't find anything by > Monday I reckon we should pick this up. FWIW, that hasn't hit anything so far. It would be good if we could explicitly nots which mm test suite and/or stress tests are happy with this, but otherwise this looks good to me. Thanks, Mark. > That said, I had some minor nits on the patch; I'm not sure if you'd be happy > to apply the suggested changes when applying or if you'd prefer that Anshuman > applies those locally and sense a v3. > > Thanks, > Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel