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=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 71343C31E44 for ; Wed, 12 Jun 2019 00:36:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 539B1208C4 for ; Wed, 12 Jun 2019 00:36:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2408206AbfFLAg3 (ORCPT ); Tue, 11 Jun 2019 20:36:29 -0400 Received: from mga09.intel.com ([134.134.136.24]:50299 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407953AbfFLAgR (ORCPT ); Tue, 11 Jun 2019 20:36:17 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jun 2019 17:36:17 -0700 X-ExtLoop1: 1 Received: from allen-box.sh.intel.com ([10.239.159.136]) by orsmga001.jf.intel.com with ESMTP; 11 Jun 2019 17:36:15 -0700 From: Lu Baolu To: Joerg Roedel , David Woodhouse Cc: ashok.raj@intel.com, jacob.jun.pan@intel.com, kevin.tian@intel.com, sai.praneeth.prakhya@intel.com, cai@lca.pw, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Lu Baolu Subject: [PATCH v2 5/7] iommu/vt-d: Fix suspicious RCU usage in probe_acpi_namespace_devices() Date: Wed, 12 Jun 2019 08:28:49 +0800 Message-Id: <20190612002851.17103-6-baolu.lu@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190612002851.17103-1-baolu.lu@linux.intel.com> References: <20190612002851.17103-1-baolu.lu@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The drhd and device scope list should be iterated with the iommu global lock held. Otherwise, a suspicious RCU usage message will be displayed. [ 3.695886] ============================= [ 3.695917] WARNING: suspicious RCU usage [ 3.695950] 5.2.0-rc2+ #2467 Not tainted [ 3.695981] ----------------------------- [ 3.696014] drivers/iommu/intel-iommu.c:4569 suspicious rcu_dereference_check() usage! [ 3.696069] other info that might help us debug this: [ 3.696126] rcu_scheduler_active = 2, debug_locks = 1 [ 3.696173] no locks held by swapper/0/1. [ 3.696204] stack backtrace: [ 3.696241] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.2.0-rc2+ #2467 [ 3.696370] Call Trace: [ 3.696404] dump_stack+0x85/0xcb [ 3.696441] intel_iommu_init+0x128c/0x13ce [ 3.696478] ? kmem_cache_free+0x16b/0x2c0 [ 3.696516] ? __fput+0x14b/0x270 [ 3.696550] ? __call_rcu+0xb7/0x300 [ 3.696583] ? get_max_files+0x10/0x10 [ 3.696631] ? set_debug_rodata+0x11/0x11 [ 3.696668] ? e820__memblock_setup+0x60/0x60 [ 3.696704] ? pci_iommu_init+0x16/0x3f [ 3.696737] ? set_debug_rodata+0x11/0x11 [ 3.696770] pci_iommu_init+0x16/0x3f [ 3.696805] do_one_initcall+0x5d/0x2e4 [ 3.696844] ? set_debug_rodata+0x11/0x11 [ 3.696880] ? rcu_read_lock_sched_held+0x6b/0x80 [ 3.696924] kernel_init_freeable+0x1f0/0x27c [ 3.696961] ? rest_init+0x260/0x260 [ 3.696997] kernel_init+0xa/0x110 [ 3.697028] ret_from_fork+0x3a/0x50 Fixes: fa212a97f3a36 ("iommu/vt-d: Probe DMA-capable ACPI name space devices") Signed-off-by: Lu Baolu --- drivers/iommu/intel-iommu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 19c4c387a3f6..84e650c6a46d 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -4793,8 +4793,10 @@ int __init intel_iommu_init(void) cpuhp_setup_state(CPUHP_IOMMU_INTEL_DEAD, "iommu/intel:dead", NULL, intel_iommu_cpu_dead); + 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) { -- 2.17.1