From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753330AbeEORtE (ORCPT ); Tue, 15 May 2018 13:49:04 -0400 Received: from merlin.infradead.org ([205.233.59.134]:57118 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752458AbeEORtC (ORCPT ); Tue, 15 May 2018 13:49:02 -0400 Date: Tue, 15 May 2018 19:48:37 +0200 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Thomas Gleixner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Davidlohr Bueso , "Theodore Y. Ts'o" , Oleg Nesterov , Amir Goldstein , Jan Kara , Matthew Wilcox Subject: Re: [PATCH v3 1/2] locking/rwsem: Add a new RWSEM_ANONYMOUSLY_OWNED flag Message-ID: <20180515174837.GL12217@hirez.programming.kicks-ass.net> References: <1526405884-4860-1-git-send-email-longman@redhat.com> <1526405884-4860-2-git-send-email-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1526405884-4860-2-git-send-email-longman@redhat.com> User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 15, 2018 at 01:38:03PM -0400, Waiman Long wrote: > diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c > index 30465a2..b7208e1 100644 > --- a/kernel/locking/rwsem.c > +++ b/kernel/locking/rwsem.c > @@ -130,7 +130,8 @@ void up_read(struct rw_semaphore *sem) > void up_write(struct rw_semaphore *sem) > { > rwsem_release(&sem->dep_map, 1, _RET_IP_); > - DEBUG_RWSEMS_WARN_ON(sem->owner != current); > + DEBUG_RWSEMS_WARN_ON((sem->owner != current) && > + !rwsem_has_anonymous_owner(sem->owner)); Why? Don't we always do percpu_rwsem_acquire() before up? > > rwsem_clear_owner(sem); > __up_write(sem);