Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753706AbbDJCsJ (ORCPT ); Thu, 9 Apr 2015 22:48:09 -0400 Received: from mga02.intel.com ([134.134.136.20]:55013 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753130AbbDJCsH (ORCPT ); Thu, 9 Apr 2015 22:48:07 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,554,1422950400"; d="scan'208";a="706627587" From: "Liu, XinwuX" To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org Cc: lin.z.chen@intel.com, bo.he@intel.com, "Liu, XinwuX" Subject: [PATCH] Fix the deadlock in uevent_buffer_pm_notify Date: Sat, 11 Apr 2015 10:49:17 +0800 Message-Id: <1428720557-13690-1-git-send-email-xinwux.liu@intel.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2608 Lines: 69 From: "Liu, XinwuX" When suspend finish uevent_buffer_pm_notify will traverse buffer_list and clean up some kobj that refcount equals zero, it will trigger kobject_event and get uevent_buffer_mutex again. That will cause deadlock. Workqueue: auto_suspend try_to_suspend Call Trace: [<8086a9ad>] ? preempt_count_sub+0xad/0x100 [<8087c237>] ? __wake_up_common+0x47/0x70 [<8086a9ad>] ? preempt_count_sub+0xad/0x100 [<80ee5ea3>] schedule+0x23/0x60 [<80ee6147>] schedule_preempt_disabled+0x17/0x30 [<80ee876b>] __mutex_lock_slowpath+0x10b/0x370 [<80ee89e0>] mutex_lock+0x10/0x1c [<80ab5813>] kobject_uevent_env+0x2d3/0x4a0 [<80ab59ea>] kobject_uevent+0xa/0x10 [<80ab4339>] kobject_cleanup+0xb9/0x1b0 [<80ee865d>] ? mutex_unlock+0xd/0x10 [<80ab53c4>] ? kobject_deliver_uevent+0x174/0x220 [<80ab5110>] ? uevent_net_exit+0x70/0x70 [<80ab41a5>] kobject_put+0x25/0x60 [<80ab550e>] ? uevent_buffer_pm_notify+0x9e/0xd0 [<80ac78bb>] ? list_del+0xb/0x20 [<80ab54ef>] uevent_buffer_pm_notify+0x7f/0xd0 [<80861597>] notifier_call_chain+0x47/0x90 [<80861713>] __blocking_notifier_call_chain+0x43/0x70 [<8086175f>] blocking_notifier_call_chain+0x1f/0x30 [<808865d6>] pm_notifier_call_chain+0x16/0x30 [<8088730d>] pm_suspend+0x1ad/0x220 [<808879c5>] try_to_suspend+0xa5/0xc0 [<80ee9b5d>] ? _raw_spin_unlock_irq+0x1d/0x40 [<80856893>] process_one_work+0x113/0x3e0 [<8084b49d>] ? mod_timer+0xed/0x200 [<8086aa55>] ? preempt_count_add+0x55/0xa0 [<80857a37>] worker_thread+0xf7/0x320 [<80857940>] ? manage_workers.isra.24+0x290/0x290 [<8085d21b>] kthread+0x9b/0xb0 [<80eea9f7>] ret_from_kernel_thread+0x1b/0x28 [<8085d180>] ? flush_kthread_worker+0xb0/0xb0 Change-Id: Iaf62ccd7a729f3eff1b5565f4b7b0d7eb01bc6a6 Signed-off-by: Liu, XinwuX --- lib/kobject_uevent.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index 40d97a9..abebf46 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -507,7 +507,9 @@ int uevent_buffer_pm_notify(struct notifier_block *nb, kobject_deliver_uevent(ub->kobj, ub->env, ub->action, ub->devpath, ub->subsys); list_del(&ub->buffer_list); + mutex_unlock(&uevent_buffer_mutex); kobject_put(ub->kobj); + mutex_lock(&uevent_buffer_mutex); kfree(ub->env); kfree(ub->devpath); kfree(ub->subsys); -- 1.7.9.5 -- 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/