From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751386AbdLARLF (ORCPT ); Fri, 1 Dec 2017 12:11:05 -0500 Received: from verein.lst.de ([213.95.11.211]:37163 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750782AbdLARLE (ORCPT ); Fri, 1 Dec 2017 12:11:04 -0500 Date: Fri, 1 Dec 2017 18:11:02 +0100 From: Christoph Hellwig To: Jason Baron Cc: Christoph Hellwig , Andrew Morton , Ingo Molnar , Peter Zijlstra , Al Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: waitqueue lockdep annotation Message-ID: <20171201171102.GA20072@lst.de> References: <20171130142037.19339-1-hch@lst.de> <20171130125050.1faba3f06fc572846f792f17@linux-foundation.org> <20171130221126.GA31795@lst.de> <21c34413-d178-fda0-91b2-6ab02c6d5a06@akamai.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <21c34413-d178-fda0-91b2-6ab02c6d5a06@akamai.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 30, 2017 at 05:18:07PM -0500, Jason Baron wrote: > Yes, but for those cases it uses the ep->poll_wait waitqueue not the > ep->wq, which is guarded by the ep->wq->lock. True. So it looks like we have one waitqueue in the system that is special in providing its own synchronization for waitqueues while entirely ignoring the waitqueue code documentation that states that waitqueues are internally synchronized. We could drop the lockdep annotation, updated the documentation and not add any validation of the assumptions, or just make epoll fit the scheme used by everyone else. So either we can drop these patches, or I need to fix up more of the epoll code.