From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2AEDCC46475 for ; Thu, 25 Oct 2018 15:27:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F006D20834 for ; Thu, 25 Oct 2018 15:27:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F006D20834 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sipsolutions.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727583AbeJZABG (ORCPT ); Thu, 25 Oct 2018 20:01:06 -0400 Received: from s3.sipsolutions.net ([144.76.43.62]:44654 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727367AbeJZABG (ORCPT ); Thu, 25 Oct 2018 20:01:06 -0400 Received: by sipsolutions.net with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.91) (envelope-from ) id 1gFhY3-0004Vj-4a; Thu, 25 Oct 2018 17:27:47 +0200 Message-ID: <8e7bac982621666375c2f5698e995f443343b3ad.camel@sipsolutions.net> Subject: Re: [PATCH 0/3] Suppress false positives triggered by workqueue lockdep annotations From: Johannes Berg To: Bart Van Assche , Tejun Heo Cc: "linux-kernel@vger.kernel.org" , Christoph Hellwig , Sagi Grimberg , "tytso@mit.edu" Date: Thu, 25 Oct 2018 17:27:28 +0200 In-Reply-To: <20181025150540.259281-1-bvanassche@acm.org> References: <20181025150540.259281-1-bvanassche@acm.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-1.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Bart, > In my tests with kernel v4.19 I noticed that several new false positive > reports were generated by the workqueue lockdep annotations. This patch > series addresses one of these false positives. I tried my best to explain why they're not false positives as far as lockdep is concerned, so I'd appreciate if you could address *why* you actually think they are such. I can understand that they are false positives as far as the code *causing* this is concerned, but this isn't how lockdep works. It generally tracks any dependency between "locks" (timers also, btw.) at any time, to later be able to find issues. This, however, should be solved at the places that actually show the problem, not by making the lockdep annotations less powerful. johannes