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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 9C31CC49EA7 for ; Thu, 24 Jun 2021 11:34:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 825AE611AC for ; Thu, 24 Jun 2021 11:34:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232418AbhFXLgl (ORCPT ); Thu, 24 Jun 2021 07:36:41 -0400 Received: from foss.arm.com ([217.140.110.172]:54654 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232363AbhFXLgk (ORCPT ); Thu, 24 Jun 2021 07:36:40 -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 884CA11FB; Thu, 24 Jun 2021 04:34:21 -0700 (PDT) Received: from [10.57.9.136] (unknown [10.57.9.136]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 361C23F718; Thu, 24 Jun 2021 04:34:14 -0700 (PDT) Subject: Re: [PATCH v14 06/12] swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing To: Will Deacon Cc: Claire Chang , Christoph Hellwig , Qian Cai , Rob Herring , mpe@ellerman.id.au, Joerg Roedel , Frank Rowand , Konrad Rzeszutek Wilk , boris.ostrovsky@oracle.com, jgross@suse.com, Marek Szyprowski , heikki.krogerus@linux.intel.com, thomas.hellstrom@linux.intel.com, peterz@infradead.org, benh@kernel.crashing.org, joonas.lahtinen@linux.intel.com, dri-devel@lists.freedesktop.org, chris@chris-wilson.co.uk, grant.likely@arm.com, paulus@samba.org, mingo@kernel.org, Jianxiong Gao , Stefano Stabellini , Saravana Kannan , xypron.glpk@gmx.de, "Rafael J . Wysocki" , Bartosz Golaszewski , bskeggs@redhat.com, linux-pci@vger.kernel.org, xen-devel@lists.xenproject.org, Thierry Reding , intel-gfx@lists.freedesktop.org, matthew.auld@intel.com, linux-devicetree , Daniel Vetter , airlied@linux.ie, maarten.lankhorst@linux.intel.com, linuxppc-dev@lists.ozlabs.org, jani.nikula@linux.intel.com, Nicolas Boichat , rodrigo.vivi@intel.com, Bjorn Helgaas , Dan Williams , Andy Shevchenko , Greg KH , Randy Dunlap , lkml , "list@263.net:IOMMU DRIVERS" , Jim Quinlan , Tom Lendacky , bauerman@linux.ibm.com References: <20210619034043.199220-1-tientzu@chromium.org> <20210619034043.199220-7-tientzu@chromium.org> <76c3343d-72e5-9df3-8924-5474ee698ef4@quicinc.com> <20210623183736.GA472@willie-the-truck> <19d4c7a2-744d-21e0-289c-a576e1f0e6f3@quicinc.com> <20210624054315.GA25381@lst.de> <364e6715-eafd-fc4a-e0af-ce2a042756b4@arm.com> <20210624111855.GA1382@willie-the-truck> From: Robin Murphy Message-ID: <452155d2-c98e-23f6-86d6-3a2ff2e74783@arm.com> Date: Thu, 24 Jun 2021 12:34:09 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210624111855.GA1382@willie-the-truck> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 2021-06-24 12:18, Will Deacon wrote: > On Thu, Jun 24, 2021 at 12:14:39PM +0100, Robin Murphy wrote: >> On 2021-06-24 07:05, Claire Chang wrote: >>> On Thu, Jun 24, 2021 at 1:43 PM Christoph Hellwig wrote: >>>> >>>> On Wed, Jun 23, 2021 at 02:44:34PM -0400, Qian Cai wrote: >>>>> is_swiotlb_force_bounce at /usr/src/linux-next/./include/linux/swiotlb.h:119 >>>>> >>>>> is_swiotlb_force_bounce() was the new function introduced in this patch here. >>>>> >>>>> +static inline bool is_swiotlb_force_bounce(struct device *dev) >>>>> +{ >>>>> + return dev->dma_io_tlb_mem->force_bounce; >>>>> +} >>>> >>>> To me the crash looks like dev->dma_io_tlb_mem is NULL. Can you >>>> turn this into : >>>> >>>> return dev->dma_io_tlb_mem && dev->dma_io_tlb_mem->force_bounce; >>>> >>>> for a quick debug check? >>> >>> I just realized that dma_io_tlb_mem might be NULL like Christoph >>> pointed out since swiotlb might not get initialized. >>> However, `Unable to handle kernel paging request at virtual address >>> dfff80000000000e` looks more like the address is garbage rather than >>> NULL? >>> I wonder if that's because dev->dma_io_tlb_mem is not assigned >>> properly (which means device_initialize is not called?). >> >> What also looks odd is that the base "address" 0xdfff800000000000 is held in >> a couple of registers, but the offset 0xe looks too small to match up to any >> relevant structure member in that dereference chain :/ > > FWIW, I've managed to trigger a NULL dereference locally when swiotlb hasn't > been initialised but we dereference 'dev->dma_io_tlb_mem', so I think > Christoph's suggestion is needed regardless. Ack to that - for SWIOTLB_NO_FORCE, io_tlb_default_mem will remain NULL. The massive jump in KernelCI baseline failures as of yesterday looks like every arm64 machine with less than 4GB of RAM blowing up... Robin. > But I agree that it won't help > with the issue reported by Qian Cai. > > Qian Cai: please can you share your .config and your command line? > > Thanks, > > Will >