From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932430AbdCTSNN (ORCPT ); Mon, 20 Mar 2017 14:13:13 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:40660 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756448AbdCTSCR (ORCPT ); Mon, 20 Mar 2017 14:02:17 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Niklas Cassel , "Peter Zijlstra (Intel)" , mhocko@suse.com, Andrew Morton , Linus Torvalds , Niklas Cassel , "Paul E. McKenney" , Thomas Gleixner , Ingo Molnar Subject: [PATCH 4.10 61/63] locking/rwsem: Fix down_write_killable() for CONFIG_RWSEM_GENERIC_SPINLOCK=y Date: Mon, 20 Mar 2017 18:52:26 +0100 Message-Id: <20170320174747.201103145@linuxfoundation.org> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170320174742.712298584@linuxfoundation.org> References: <20170320174742.712298584@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Niklas Cassel commit 17fcbd590d0c3e35bd9646e2215f86586378bc42 upstream. We hang if SIGKILL has been sent, but the task is stuck in down_read() (after do_exit()), even though no task is doing down_write() on the rwsem in question: INFO: task libupnp:21868 blocked for more than 120 seconds. libupnp D 0 21868 1 0x08100008 ... Call Trace: __schedule() schedule() __down_read() do_exit() do_group_exit() __wake_up_parent() This bug has already been fixed for CONFIG_RWSEM_XCHGADD_ALGORITHM=y in the following commit: 04cafed7fc19 ("locking/rwsem: Fix down_write_killable()") ... however, this bug also exists for CONFIG_RWSEM_GENERIC_SPINLOCK=y. Signed-off-by: Niklas Cassel Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Andrew Morton Cc: Linus Torvalds Cc: Niklas Cassel Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: d47996082f52 ("locking/rwsem: Introduce basis for down_write_killable()") Link: http://lkml.kernel.org/r/1487981873-12649-1-git-send-email-niklass@axis.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/locking/rwsem-spinlock.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) --- a/kernel/locking/rwsem-spinlock.c +++ b/kernel/locking/rwsem-spinlock.c @@ -216,10 +216,8 @@ int __sched __down_write_common(struct r */ if (sem->count == 0) break; - if (signal_pending_state(state, current)) { - ret = -EINTR; - goto out; - } + if (signal_pending_state(state, current)) + goto out_nolock; set_task_state(tsk, state); raw_spin_unlock_irqrestore(&sem->wait_lock, flags); schedule(); @@ -227,12 +225,19 @@ int __sched __down_write_common(struct r } /* got the lock */ sem->count = -1; -out: list_del(&waiter.list); raw_spin_unlock_irqrestore(&sem->wait_lock, flags); return ret; + +out_nolock: + list_del(&waiter.list); + if (!list_empty(&sem->wait_list)) + __rwsem_do_wake(sem, 1); + raw_spin_unlock_irqrestore(&sem->wait_lock, flags); + + return -EINTR; } void __sched __down_write(struct rw_semaphore *sem)