From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965954AbcDLPoG (ORCPT ); Tue, 12 Apr 2016 11:44:06 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:55386 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965794AbcDLPns (ORCPT ); Tue, 12 Apr 2016 11:43:48 -0400 X-IBM-Helo: d03dlp03.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, Artem Savkov Subject: [PATCH tip/core/rcu 14/24] rcuperf: Do not wake up shutdown wait queue if "shutdown" is false. Date: Tue, 12 Apr 2016 08:43:47 -0700 Message-Id: <1460475837-26498-14-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 2.5.2 In-Reply-To: <20160412154332.GA24983@linux.vnet.ibm.com> References: <20160412154332.GA24983@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16041215-0029-0000-0000-000022C68D89 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Artem Savkov After finishing its tests rcuperf tries to wake up shutdown_wq even if "shutdown" param is set to false, resulting in a wake_up() call on an unitialized wait_queue_head_t which leads to "BUG: spinlock bad magic" and "BUG: unable to handle kernel NULL pointer dereference". Fix by checking "shutdown" param before waking up the queue. Signed-off-by: Artem Savkov --- kernel/rcu/rcuperf.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c index 4c0572859ff0..3cee0d8393ed 100644 --- a/kernel/rcu/rcuperf.c +++ b/kernel/rcu/rcuperf.c @@ -423,8 +423,10 @@ rcu_perf_writer(void *arg) b_rcu_perf_writer_finished = cur_ops->completed(); } - smp_mb(); /* Assign before wake. */ - wake_up(&shutdown_wq); + if (shutdown) { + smp_mb(); /* Assign before wake. */ + wake_up(&shutdown_wq); + } } } if (done && !alldone && -- 2.5.2