Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753087AbdI0NVc (ORCPT ); Wed, 27 Sep 2017 09:21:32 -0400 Received: from goliath.siemens.de ([192.35.17.28]:45357 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751959AbdI0NVb (ORCPT ); Wed, 27 Sep 2017 09:21:31 -0400 Subject: Re: intel-dmar: possible circular locking dependency detected From: Jan Kiszka To: iommu@lists.linux-foundation.org, Linux Kernel Mailing List , Joerg Roedel References: <4e9f9665-38f7-c5f0-2a9d-13bb3a00aab2@siemens.com> Message-ID: <6ed4183a-b2eb-b8d3-c54c-fb0c4fd7a813@siemens.com> Date: Wed, 27 Sep 2017 15:21:21 +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 In-Reply-To: <4e9f9665-38f7-c5f0-2a9d-13bb3a00aab2@siemens.com> 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: 4646 Lines: 134 On 2017-09-27 14:14, Jan Kiszka wrote: > 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 > Oh, just realized that I already sent this report earlier this year [1] but didn't receive any feedback so far. Jan [1] https://lkml.org/lkml/2017/7/24/238 -- Siemens AG, Corporate Technology, CT RDA ITP SES-DE Corporate Competence Center Embedded Linux