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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 A854CC2D0A3 for ; Thu, 12 Nov 2020 08:52:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5E5D02100A for ; Thu, 12 Nov 2020 08:52:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727132AbgKLIwi (ORCPT ); Thu, 12 Nov 2020 03:52:38 -0500 Received: from lgeamrelo13.lge.com ([156.147.23.53]:34154 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725902AbgKLIwi (ORCPT ); Thu, 12 Nov 2020 03:52:38 -0500 Received: from unknown (HELO lgeamrelo01.lge.com) (156.147.1.125) by 156.147.23.53 with ESMTP; 12 Nov 2020 17:52:35 +0900 X-Original-SENDERIP: 156.147.1.125 X-Original-MAILFROM: byungchul.park@lge.com Received: from unknown (HELO X58A-UD3R) (10.177.222.33) by 156.147.1.125 with ESMTP; 12 Nov 2020 17:52:35 +0900 X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com Date: Thu, 12 Nov 2020 17:51:14 +0900 From: Byungchul Park To: Ingo Molnar Cc: torvalds@linux-foundation.org, peterz@infradead.org, mingo@redhat.com, will@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, rostedt@goodmis.org, joel@joelfernandes.org, alexander.levin@microsoft.com, daniel.vetter@ffwll.ch, chris@chris-wilson.co.uk, duyuyang@gmail.com, johannes.berg@intel.com, tj@kernel.org, tytso@mit.edu, willy@infradead.org, david@fromorbit.com, amir73il@gmail.com, bfields@fieldses.org, gregkh@linuxfoundation.org, kernel-team@lge.com Subject: Re: [RFC] Are you good with Lockdep? Message-ID: <20201112085114.GC14554@X58A-UD3R> References: <20201111050559.GA24438@X58A-UD3R> <20201111105441.GA78848@gmail.com> <20201112061532.GA14554@X58A-UD3R> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201112061532.GA14554@X58A-UD3R> User-Agent: Mutt/1.5.21 (2010-09-15) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 12, 2020 at 03:15:32PM +0900, Byungchul Park wrote: > > If on the other hand there's some bug in lockdep itself that causes > > excessive false positives, it's better to limit the number of reports > > to one per bootup, so that it's not seen as a nuisance debugging > > facility. > > > > Or if lockdep gets extended that causes multiple previously unreported > > (but very much real) bugs to be reported, it's *still* better to > > handle them one by one: because lockdep doesn't know whether it's real > > Why do you think we cannot handle them one by one with multi-reporting? > We can handle them with the first one as we do with single-reporting. > And also that's how we work, for example, when building the kernel or > somethinig. Let me add a little bit more. I just said the fact that we are able to handle the bugs one by one as if we do with single-reporting. But the thing is multi-reporting could be more useful in some cases. More precisely speaking, bugs not caused by IRQ state will be reported without annoying nuisance. I bet you have experienced a ton of nuisances when multi-reporting Lockdep detected a deadlock by IRQ state. For some cases, multi-reporting is as useful as single-reporting, while for the other cases, multi-reporting is more useful. Then I think we have to go with mutil-reporting if there's no technical issue. Thanks, Byungchul