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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 895A7C2BB84 for ; Wed, 16 Sep 2020 20:24:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1AE0C21D1B for ; Wed, 16 Sep 2020 20:24:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Kzrqmxbs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728396AbgIPUYY (ORCPT ); Wed, 16 Sep 2020 16:24:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60724 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727090AbgIPR2V (ORCPT ); Wed, 16 Sep 2020 13:28:21 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95E8DC0698E0 for ; Wed, 16 Sep 2020 04:51:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=z9WWijjbR2uBiL+KUZRKbMWPO3w9bu66TpFyviEWxgU=; b=KzrqmxbsJhALZYZchk5+ye8x0L UrPqUzSFf4IuLfor+B3fpLQc02EPdViLN6Lz1Y/u7Cm0FUUr19SUlz7D0qhwdArn6mtXBA0cnbI06 4CROo9MfiWJbpoMRtDXk+JCWQBbDiX2S/i1EcFAeAhbgGFxD/hNsb8MgSM92nM61AlS2zyBUaCOzY 2vaBYs/XPwmlXLsvKgvpkfFxngKEOlqSmAJoK6ZYuAWCUkStMM9UCrYI71Q1EcTchVELijBHhtxrt 7LZNFtgHFHoBxsjv8Hza8N31NWfiQj0bxubOYCQMPagfLHcyv2SqIESmuXjhQ2qGW6AQEBgkj4shd 5q5uUg6Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kIVxl-0008P9-T4; Wed, 16 Sep 2020 11:51:02 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 2E0583012DF; Wed, 16 Sep 2020 13:50:58 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 10CE321242349; Wed, 16 Sep 2020 13:50:58 +0200 (CEST) Date: Wed, 16 Sep 2020 13:50:57 +0200 From: peterz@infradead.org To: Dmitry Vyukov Cc: Tetsuo Handa , Ingo Molnar , Will Deacon , Andrew Morton , LKML , syzkaller Subject: Re: [PATCH v2] lockdep: Allow tuning tracing capacity constants. Message-ID: <20200916115057.GO2674@hirez.programming.kicks-ass.net> References: <1595640639-9310-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> <384ce711-25c5-553b-8d22-965847132fbd@i-love.sakura.ne.jp> <0f7233f7-a04a-e9c9-7920-3a170cc97e4b@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 16, 2020 at 01:28:19PM +0200, Dmitry Vyukov wrote: > On Fri, Sep 4, 2020 at 6:05 PM Tetsuo Handa > wrote: > > > > Hello. Can we apply this patch? > > > > This patch addresses top crashers for syzbot, and applying this patch > > will help utilizing syzbot's resource for finding other bugs. > > Acked-by: Dmitry Vyukov > > Peter, do you still have concerns with this? Yeah, I still hate it with a passion; it discourages thinking. A bad annotation that blows up the lockdep storage, no worries, we'll just increase this :/ IIRC the issue with syzbot is that the current sysfs annotation is pretty terrible and generates a gazillion classes, and syzbot likes poking at /sys a lot and thus floods the system. I don't know enough about sysfs to suggest an alternative, and haven't exactly had spare time to look into it either :/ Examples of bad annotations is getting every CPU a separate class, that leads to nr_cpus! chains if CPUs arbitrarily nest (nr_cpus^2 if there's only a single nesting level).