Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752811AbdI0MOh (ORCPT ); Wed, 27 Sep 2017 08:14:37 -0400 Received: from thoth.sbs.de ([192.35.17.2]:55853 "EHLO thoth.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752387AbdI0MOg (ORCPT ); Wed, 27 Sep 2017 08:14:36 -0400 To: iommu@lists.linux-foundation.org, Linux Kernel Mailing List From: Jan Kiszka Subject: intel-dmar: possible circular locking dependency detected Message-ID: <4e9f9665-38f7-c5f0-2a9d-13bb3a00aab2@siemens.com> Date: Wed, 27 Sep 2017 14:14:29 +0200 User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4203 Lines: 125 Hi, while I'm triggering this with a still out-of-tree module from the Jailhouse project, the potential deadlock appears to me being unrelated to it. Please have a look: ====================================================== WARNING: possible circular locking dependency detected 4.14.0-rc2-dbg+ #176 Tainted: G O ------------------------------------------------------ jailhouse/6105 is trying to acquire lock: dmar_pci_bus_notifier+0x4f/0xcb but task is already holding lock: __blocking_notifier_call_chain+0x31/0x65 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&(&priv->bus_notifier)->rwsem){++++}: __lock_acquire+0xed7/0x113b lock_acquire+0x148/0x1f6 down_write+0x3b/0x6a blocking_notifier_chain_register+0x33/0x53 bus_register_notifier+0x1c/0x1e dmar_dev_scope_init+0x2c6/0x2db intel_iommu_init+0xec/0x11c2 pci_iommu_init+0x17/0x41 do_one_initcall+0x90/0x143 kernel_init_freeable+0x1cc/0x256 kernel_init+0xe/0xf8 ret_from_fork+0x2a/0x40 -> #0 (dmar_global_lock){++++}: check_prev_add+0x112/0x65f __lock_acquire+0xed7/0x113b lock_acquire+0x148/0x1f6 down_write+0x3b/0x6a dmar_pci_bus_notifier+0x4f/0xcb notifier_call_chain+0x3c/0x5e __blocking_notifier_call_chain+0x4c/0x65 blocking_notifier_call_chain+0x14/0x16 device_add+0x40c/0x522 pci_device_add+0x1c0/0x1ce pci_scan_single_device+0x92/0x9d pci_scan_slot+0x59/0x10a jailhouse_pci_do_all_devices+0x74/0x263 [jailhouse] jailhouse_pci_virtual_root_devices_add+0x40/0x42 [jailhouse] jailhouse_cmd_enable+0x4fd/0x5e8 [jailhouse] jailhouse_ioctl+0x28/0x70 [jailhouse] vfs_ioctl+0x18/0x34 do_vfs_ioctl+0x51b/0x5e3 SyS_ioctl+0x50/0x7b entry_SYSCALL_64_fastpath+0x1f/0xbe other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&priv->bus_notifier)->rwsem); lock(dmar_global_lock); lock(&(&priv->bus_notifier)->rwsem); lock(dmar_global_lock); *** DEADLOCK *** 2 locks held by jailhouse/6105: jailhouse_cmd_enable+0x130/0x5e8 [jailhouse] __blocking_notifier_call_chain+0x31/0x65 stack backtrace: CPU: 1 PID: 6105 Comm: jailhouse Tainted: G O 4.14.0-rc2-dbg+ #176 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014 Call Trace: dump_stack+0x85/0xbe print_circular_bug+0x389/0x398 ? add_lock_to_list.isra.23+0x96/0x96 check_prev_add+0x112/0x65f ? kernel_text_address+0x1c/0x6a ? add_lock_to_list.isra.23+0x96/0x96 __lock_acquire+0xed7/0x113b ? __lock_acquire+0xed7/0x113b lock_acquire+0x148/0x1f6 ? dmar_pci_bus_notifier+0x4f/0xcb down_write+0x3b/0x6a ? dmar_pci_bus_notifier+0x4f/0xcb dmar_pci_bus_notifier+0x4f/0xcb notifier_call_chain+0x3c/0x5e __blocking_notifier_call_chain+0x4c/0x65 blocking_notifier_call_chain+0x14/0x16 device_add+0x40c/0x522 pci_device_add+0x1c0/0x1ce pci_scan_single_device+0x92/0x9d pci_scan_slot+0x59/0x10a jailhouse_pci_do_all_devices+0x74/0x263 [jailhouse] jailhouse_pci_virtual_root_devices_add+0x40/0x42 [jailhouse] jailhouse_cmd_enable+0x4fd/0x5e8 [jailhouse] jailhouse_ioctl+0x28/0x70 [jailhouse] vfs_ioctl+0x18/0x34 do_vfs_ioctl+0x51b/0x5e3 ? kmem_cache_free+0x15b/0x1fa ? entry_SYSCALL_64_fastpath+0x5/0xbe ? trace_hardirqs_on_caller+0x180/0x19c SyS_ioctl+0x50/0x7b entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x7f8b3b110d87 RSP: 002b:00007ffc44b70088 EFLAGS: 00000206 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000046 RCX: 00007f8b3b110d87 RDX: 0000000000604010 RSI: 0000000040080000 RDI: 0000000000000003 RBP: 0000000000604010 R08: 00007f8b3b3ade80 R09: 00000000000885d0 R10: 00007ffc44b6fe40 R11: 0000000000000206 R12: 00000000000025d4 R13: 0000000000000000 R14: 00007ffc44b714a4 R15: 0000000000000000 Thanks, Jan -- Siemens AG, Corporate Technology, CT RDA ITP SES-DE Corporate Competence Center Embedded Linux