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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT 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 37FBCC0044C for ; Mon, 29 Oct 2018 12:16:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B60EE20664 for ; Mon, 29 Oct 2018 12:16:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B60EE20664 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-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729240AbeJ2VE6 (ORCPT ); Mon, 29 Oct 2018 17:04:58 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:39588 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728950AbeJ2VE6 (ORCPT ); Mon, 29 Oct 2018 17:04:58 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 391EE80D; Mon, 29 Oct 2018 05:16:32 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 095DB3F6A8; Mon, 29 Oct 2018 05:16:32 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 0333F1AE091C; Mon, 29 Oct 2018 12:16:38 +0000 (GMT) Date: Mon, 29 Oct 2018 12:16:38 +0000 From: Will Deacon To: John Garry Cc: catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxarm@huawei.com Subject: Re: [PATCH] arm64/numa: Add more vetting in numa_set_distance() Message-ID: <20181029121638.GB15446@arm.com> References: <1540562267-101152-1-git-send-email-john.garry@huawei.com> <20181029112504.GF14127@arm.com> <925009c6-226d-213f-dbcb-68b772d80a18@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <925009c6-226d-213f-dbcb-68b772d80a18@huawei.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 29, 2018 at 12:14:09PM +0000, John Garry wrote: > On 29/10/2018 11:25, Will Deacon wrote: > >On Fri, Oct 26, 2018 at 09:57:47PM +0800, John Garry wrote: > >>Currently it is acceptable to set the distance between 2 separate nodes to > >>LOCAL_DISTANCE. > >> > >>Reject this as it is invalid. > >> > >>This change avoids a crash reported in [1]. > >> > >>[1] https://www.spinics.net/lists/arm-kernel/msg683304.html > >> > >>Signed-off-by: John Garry > >> > >>diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c > >>index 146c04c..6092e3d 100644 > >>--- a/arch/arm64/mm/numa.c > >>+++ b/arch/arm64/mm/numa.c > >>@@ -335,7 +335,8 @@ void __init numa_set_distance(int from, int to, int distance) > >> } > >> > >> if ((u8)distance != distance || > >>- (from == to && distance != LOCAL_DISTANCE)) { > >>+ (from == to && distance != LOCAL_DISTANCE) || > >>+ (from != to && distance == LOCAL_DISTANCE)) { > > > >The current code here is more-or-less lifted from the x86 implementation > >of numa_set_distance(). > > Right, I did notice this. I didn't think that x86 folks would be so > concerned since they generally only use ACPI, and the ACPI code already > validates these distances in drivers/acpi/numa.c: slit_valid() [unlike OF > code]. > > I think we should either factor out the sanity check > >into a core helper or make the core code robust to these funny configurations. > > OK, so to me it would make sense to factor out a sanity check into a core > helper. That, or have the OF code perform the same validation that slit_valid() is doing for ACPI. I'm just trying to avoid other architectures running into this problem down the line. Will