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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 25AC9C10F00 for ; Sat, 7 Mar 2020 11:52:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F2FC62070A for ; Sat, 7 Mar 2020 11:52:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726252AbgCGLwb (ORCPT ); Sat, 7 Mar 2020 06:52:31 -0500 Received: from mga17.intel.com ([192.55.52.151]:37877 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726116AbgCGLwb (ORCPT ); Sat, 7 Mar 2020 06:52:31 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 07 Mar 2020 03:52:30 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,525,1574150400"; d="scan'208";a="388090627" Received: from blu2-mobl3.ccr.corp.intel.com (HELO [10.254.211.93]) ([10.254.211.93]) by orsmga004.jf.intel.com with ESMTP; 07 Mar 2020 03:52:28 -0800 Cc: baolu.lu@linux.intel.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] iommu/vt-d: fix RCU-list bugs in intel_iommu_init To: Qian Cai , jroedel@suse.de References: <1583438446-9959-1-git-send-email-cai@lca.pw> From: Lu Baolu Message-ID: <4d2297b6-f719-68d5-973b-df9405caa7a0@linux.intel.com> Date: Sat, 7 Mar 2020 19:52:27 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <1583438446-9959-1-git-send-email-cai@lca.pw> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2020/3/6 4:00, Qian Cai wrote: > There are several places traverse RCU-list without holding any lock in > intel_iommu_init(). Fix them by acquiring dmar_global_lock. > > WARNING: suspicious RCU usage > ----------------------------- > drivers/iommu/intel-iommu.c:5216 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > rcu_scheduler_active = 2, debug_locks = 1 > no locks held by swapper/0/1. > > Call Trace: > dump_stack+0xa0/0xea > lockdep_rcu_suspicious+0x102/0x10b > intel_iommu_init+0x947/0xb13 > pci_iommu_init+0x26/0x62 > do_one_initcall+0xfe/0x500 > kernel_init_freeable+0x45a/0x4f8 > kernel_init+0x11/0x139 > ret_from_fork+0x3a/0x50 > DMAR: Intel(R) Virtualization Technology for Directed I/O > > Fixes: d8190dc63886 ("iommu/vt-d: Enable DMA remapping after rmrr mapped") > Signed-off-by: Qian Cai Thanks for the fix. Acked-by: Lu Baolu Best regards, baolu > --- > drivers/iommu/intel-iommu.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index 6fa6de2b6ad5..bc138ceb07bc 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -5193,6 +5193,7 @@ int __init intel_iommu_init(void) > > init_iommu_pm_ops(); > > + down_read(&dmar_global_lock); > for_each_active_iommu(iommu, drhd) { > iommu_device_sysfs_add(&iommu->iommu, NULL, > intel_iommu_groups, > @@ -5200,6 +5201,7 @@ int __init intel_iommu_init(void) > iommu_device_set_ops(&iommu->iommu, &intel_iommu_ops); > iommu_device_register(&iommu->iommu); > } > + up_read(&dmar_global_lock); > > bus_set_iommu(&pci_bus_type, &intel_iommu_ops); > if (si_domain && !hw_pass_through) > @@ -5210,7 +5212,6 @@ int __init intel_iommu_init(void) > down_read(&dmar_global_lock); > if (probe_acpi_namespace_devices()) > pr_warn("ACPI name space devices didn't probe correctly\n"); > - up_read(&dmar_global_lock); > > /* Finally, we enable the DMA remapping hardware. */ > for_each_iommu(iommu, drhd) { > @@ -5219,6 +5220,8 @@ int __init intel_iommu_init(void) > > iommu_disable_protect_mem_regions(iommu); > } > + up_read(&dmar_global_lock); > + > pr_info("Intel(R) Virtualization Technology for Directed I/O\n"); > > intel_iommu_enabled = 1; >