Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753859AbbDGL01 (ORCPT ); Tue, 7 Apr 2015 07:26:27 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:60471 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752661AbbDGL0Z (ORCPT ); Tue, 7 Apr 2015 07:26:25 -0400 From: "Rafael J. Wysocki" To: Xie XiuQi Cc: lenb@kernel.org, guohanjun@huawei.com, hanjun.guo@linaro.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ACPI / HOTPLUG: fix device->physical_node_lock deadlock Date: Tue, 07 Apr 2015 13:50:48 +0200 Message-ID: <12760195.2odgqTkKju@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.19.0+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <5219717.RxvSXtBaZ8@vostro.rjw.lan> References: <1428397392-26200-1-git-send-email-xiexiuqi@huawei.com> <5219717.RxvSXtBaZ8@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2246 Lines: 52 On Tuesday, April 07, 2015 01:22:52 PM Rafael J. Wysocki wrote: > On Tuesday, April 07, 2015 05:03:12 PM Xie XiuQi wrote: > > I meet a deadlock during cpu hotplug. The code path is bellow: > > > > Call Trace: > > [] dump_stack+0x19/0x1b > > [] validate_chain.isra.43+0xf4a/0x1120 > > [] ? sched_clock+0x9/0x10 > > [] ? sched_clock_local+0x1d/0x80 > > [] ? sched_clock_cpu+0xa8/0x100 > > [] __lock_acquire+0x3c6/0xb70 > > [] ? sched_clock_cpu+0xa8/0x100 > > [] lock_acquire+0xa2/0x1f0 > > [] ? acpi_scan_is_offline+0x2c/0xa3 > > [] mutex_lock_nested+0x94/0x3f0 > > [] ? acpi_scan_is_offline+0x2c/0xa3 > > [] ? acpi_scan_is_offline+0x2c/0xa3 > > [] ? trace_hardirqs_on+0xd/0x10 > > [] acpi_scan_is_offline+0x2c/0xa3 --> LOCK (DEADLOCK) > > Is it the same device, actually? acpi_container_offline() walks the *children* > of the container while acpi_bus_offline() locks the container itself. So the patch below should make the splat go away too if I'm not mistaken. --- drivers/acpi/scan.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) Index: linux-pm/drivers/acpi/scan.c =================================================================== --- linux-pm.orig/drivers/acpi/scan.c +++ linux-pm/drivers/acpi/scan.c @@ -298,7 +298,11 @@ bool acpi_scan_is_offline(struct acpi_de struct acpi_device_physical_node *pn; bool offline = true; - mutex_lock(&adev->physical_node_lock); + /* + * acpi_container_offline() calls this for all of the container's + * children under the container's physical_node_lock lock. + */ + mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING); list_for_each_entry(pn, &adev->physical_node_list, node) if (device_supports_offline(pn->dev) && !pn->dev->offline) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/