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=-1.0 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 47D96C04EB8 for ; Fri, 30 Nov 2018 14:38:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0D93A20868 for ; Fri, 30 Nov 2018 14:38:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0D93A20868 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com 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 S1727073AbeLABsF (ORCPT ); Fri, 30 Nov 2018 20:48:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42600 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726340AbeLABsE (ORCPT ); Fri, 30 Nov 2018 20:48:04 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8DED6637ED; Fri, 30 Nov 2018 14:38:32 +0000 (UTC) Received: from llong.remote.csb (dhcp-17-8.bos.redhat.com [10.18.17.8]) by smtp.corp.redhat.com (Postfix) with ESMTP id D2E67105705E; Fri, 30 Nov 2018 14:38:31 +0000 (UTC) Subject: Re: [PATCH 0/2] locking/lockdep: Track number of zapped classes & report abuse To: Peter Zijlstra Cc: Ingo Molnar , Will Deacon , Thomas Gleixner , linux-kernel@vger.kernel.org, Bart Van Assche References: <1543531297-18349-1-git-send-email-longman@redhat.com> <20181129224836.GI11632@hirez.programming.kicks-ass.net> From: Waiman Long Openpgp: preference=signencrypt Autocrypt: addr=longman@redhat.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181129224836.GI11632@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Fri, 30 Nov 2018 14:38:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/29/2018 05:48 PM, Peter Zijlstra wrote: > On Thu, Nov 29, 2018 at 05:41:35PM -0500, Waiman Long wrote: >> When a kernel module is repeatedly load and unload, it will eventually >> exhaust the lockdep entries resulting in a bug message. This is a use >> case that the current lockdep code cannot support. >> >> This patchset tracks the number of zapped classes and print a warning if >> too many lockdep entries are wasted because of too many module unloading. >> For example, >> >> [ 2490.651531] BUG: MAX_LOCKDEP_KEYS too low! >> [ 2490.669925] turning off the locking correctness validator. >> [ 2490.669925] Please attach the output of /proc/lock_stat to the bug report >> [ 2490.669926] ======================================================== >> [ 2490.669927] WARNING: 6499 out of 8191 locks have been destroyed >> [ 2490.669927] through kernel module unload operations. >> [ 2490.669928] The corresponding lockdep entries are not reusable. >> [ 2490.669928] The system might have run out of lockdep entries because >> [ 2490.669929] of repeated kernel module load and unload operations. >> [ 2490.669929] Lockdep cannot support this particular use case. >> [ 2490.669930] -------------------------------------------------------- > Have a look here: > > https://lkml.kernel.org/r/20181128234325.110011-1-bvanassche@acm.org Thanks for the pointer, I will take a look at that. Cheers, Longman