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=-8.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 664C3C433E0 for ; Fri, 22 Jan 2021 10:04:31 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 0BA33235F7 for ; Fri, 22 Jan 2021 10:04:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0BA33235F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.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=FBMg7a3JZAjCyDH7BMCWgkTC/SgB+hir9wGqdT+bQzk=; b=xmtPhy/sX5CNhROp5BFdjvRM4 Jyg0O60UU4rkYUYu8IC4g+f2f2ecx9dzBffQEcG71qcifOloF3HjW89D8NjUkWvh+9MPf+GTWWJUP K0vh9nZzuh33cApfpgryz9oNC+2tJXwIcq1HxL/eTu2RxFy6mxM+EDdC1CPiT2lo5fkj7UM+fcv8f fLGesvRymxRemEmDzKSsX0fAYZ1J1by2GejMM0AmRnS1rrxdcIPo5+nHIJP9dWIN2CuR8x0QzwIgI AfuHA0Q7pMzeVfTnkHvlet0GXKTqBF7d08fzQGBhNt5e0Eo+UyUqk10siQ94aA1CkOUDdBbgcZQPC PVJvZ37Jw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l2tHM-0000lP-SN; Fri, 22 Jan 2021 10:02:56 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l2tHK-0000kq-QT for linux-arm-kernel@lists.infradead.org; Fri, 22 Jan 2021 10:02:55 +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 DF1AF139F; Fri, 22 Jan 2021 02:02:52 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.41.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1A3493F719; Fri, 22 Jan 2021 02:02:47 -0800 (PST) Date: Fri, 22 Jan 2021 10:02:30 +0000 From: Mark Rutland To: "Paul E. McKenney" , vincenzo.frascino@arm.com Subject: Re: rcu-torture: Internal error: Oops: 96000006 Message-ID: <20210122095925.GA29124@C02TD0UTHF1T.local> References: <20210121185521.GQ2743@paulmck-ThinkPad-P72> <20210121213110.GB23234@willie-the-truck> <20210121214314.GW2743@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210121214314.GW2743@paulmck-ThinkPad-P72> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210122_050254_936900_FC2982BD X-CRM114-Status: GOOD ( 23.08 ) 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: Peter Zijlstra , catalin.marinas@arm.com, Naresh Kamboju , open list , lkft-triage@lists.linaro.org, rcu@vger.kernel.org, Linux-Next Mailing List , Steven Rostedt , Will Deacon , Ingo Molnar , 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+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jan 21, 2021 at 01:43:14PM -0800, Paul E. McKenney wrote: > On Thu, Jan 21, 2021 at 09:31:10PM +0000, Will Deacon wrote: > > On Thu, Jan 21, 2021 at 10:55:21AM -0800, Paul E. McKenney wrote: > > > On Thu, Jan 21, 2021 at 10:37:21PM +0530, Naresh Kamboju wrote: > > > > While running rcu-torture test on qemu_arm64 and arm64 Juno-r2 device > > > > the following kernel crash noticed. This started happening from Linux next > > > > next-20210111 tag to next-20210121. > > > > > > > > metadata: > > > > git branch: master > > > > git repo: https://gitlab.com/Linaro/lkft/mirrors/next/linux-next > > > > git describe: next-20210111 > > > > kernel-config: https://builds.tuxbuild.com/1muTTn7AfqcWvH5x2Alxifn7EUH/config > > > > > > > > output log: > > > > > > > > [ 621.538050] mem_dump_obj() slab test: rcu_torture_stats = > > > > ffff0000c0a3ac40, &rhp = ffff800012debe40, rhp = ffff0000c8cba000, &z > > > > = ffff8000091ab8e0 > > > > [ 621.546662] mem_dump_obj(ZERO_SIZE_PTR): > > > > [ 621.546696] Unable to handle kernel NULL pointer dereference at > > > > virtual address 0000000000000008 > > > > [...] > > > > > Huh. I am relying on virt_addr_valid() rejecting NULL pointers and > > > things like ZERO_SIZE_PTR, which is defined as ((void *)16). It looks > > > like your configuration rejects NULL as an invalid virtual address, > > > but does not reject ZERO_SIZE_PTR. Is this the intent, given that you > > > are not allowed to dereference a ZERO_SIZE_PTR? > > > > > > Adding the ARM64 guys on CC for their thoughts. > > > > Spooky timing, there was a thread _today_ about that: > > > > https://lore.kernel.org/r/ecbc7651-82c4-6518-d4a9-dbdbdf833b5b@arm.com > > Very good, then my workaround (shown below for Naresh's ease of testing) > is only a short-term workaround. Yay! ;-) Hopefully, though we might need to check other architectures beyond arm64, ppc, and x86, to be certain! Is there any other latent use of virt_addr_valid() that needs this semantic? If so we'll probably want to backport the changes to arm64's implementation, at least for v5.10. Vincenzo, would you mind taking a look? Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel