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=-2.3 required=3.0 tests=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 9CC13C7618B for ; Wed, 24 Jul 2019 15:47:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7A1EC2238C for ; Wed, 24 Jul 2019 15:47:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728551AbfGXPrE (ORCPT ); Wed, 24 Jul 2019 11:47:04 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:37780 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727608AbfGXPrD (ORCPT ); Wed, 24 Jul 2019 11:47:03 -0400 Received: by mail-pg1-f194.google.com with SMTP id i70so10691507pgd.4 for ; Wed, 24 Jul 2019 08:47:03 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Vy+7PP8pTGQ+X9auiWqQ+l1tfzBTRZcEHjGxTn8iQ5M=; b=t3UK8y50C6nkx8jbivtKeYjUpIyQSPlULPwQMumjwYNtzJhkXHpMSxMvIERrmdg3eB uvfUxCB/Lovy0qkG2wvSYrZm6P7x3DsoJy2ME0rfNOuman4r+056cDyoV7cGmfcOzk5X nbbmgKwe3bC+EBDLZcJ0ur9OCB7iUiX1RI35B8PCmLrP1OhXfeFqdHzlAKdlQ+nRRwH6 Qqhr3eWuDFoHBmdBSVF7fWotXuYDLnPFkLP47UV8KR+pBWOxrryph1dRLnUojLQN44Rs ums5qikqJg8Htlduh8Z3KLcVb88c2ldLHYwSuSdZKF1qap0laYhtUzPmhQRKdQwrClLH IrpQ== X-Gm-Message-State: APjAAAWqq+IAMcnoq4iXTvVUR6KTdl0s+7gQhoYxfbmiaZzUwX9tW7eU f8g3oQUWCnaRMjQ8DJqvNcI= X-Google-Smtp-Source: APXvYqwM7yJkDlRA6fOFXNax17rTw0VruON9zuB3CNfJ43SO8bUzE0XM59us9YeC1R/CsSNDKnT09w== X-Received: by 2002:a62:e308:: with SMTP id g8mr12570717pfh.162.1563983223060; Wed, 24 Jul 2019 08:47:03 -0700 (PDT) Received: from asus.site ([2601:647:4000:52d2:bbe8:c2d7:f336:57bc]) by smtp.gmail.com with ESMTPSA id o14sm97085674pfh.153.2019.07.24.08.47.01 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Wed, 24 Jul 2019 08:47:02 -0700 (PDT) Subject: Re: [PATCH 3/4] locking/lockdep: Reduce space occupied by stack traces To: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, Thomas Gleixner , Will Deacon , Yuyang Du , Waiman Long References: <20190722182443.216015-1-bvanassche@acm.org> <20190722182443.216015-4-bvanassche@acm.org> <20190724045610.GC643@sol.localdomain> From: Bart Van Assche Message-ID: Date: Wed, 24 Jul 2019 08:47:00 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190724045610.GC643@sol.localdomain> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/23/19 9:56 PM, Eric Biggers wrote: > Does this also fix any of the other bugs listed at > https://lore.kernel.org/lkml/20190710055838.GC2152@sol.localdomain/ > ? > > BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low! > BUG: MAX_LOCKDEP_CHAINS too low! > BUG: MAX_LOCK_DEPTH too low! (2) > BUG: MAX_LOCKDEP_ENTRIES too low! Hi Eric, I don't think so. This patch only affects the space occupied by stack traces and not the space occupied by any of the other lockdep data strutures. BTW, in that report I found the following: Title: BUG: MAX_LOCKDEP_CHAINS too low! Last occurred: 5 days ago Reported: 284 days ago Title: BUG: MAX_LOCK_DEPTH too low! (2) Last occurred: 362 days ago Reported: 392 days ago Since these bugs were reported more than 150 days ago these bugs are older than my lockdep changes and hence not a regression due to my lockdep changes. My patch series did not increase the number of "list_entries" tracked by lockdep so I don't think that the "BUG: MAX_LOCKDEP_ENTRIES too low" behavior can be triggered more easily due to my lockdep changes. The "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" complaint however may be related. I will check whether it is possible to reduce the space occupied by held lock chains again to what was needed before my patch series. Bart.