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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 B38CBC433DF for ; Sun, 17 May 2020 01:17:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 882CE206F4 for ; Sun, 17 May 2020 01:17:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iaSiRWtO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726918AbgEQBQG (ORCPT ); Sat, 16 May 2020 21:16:06 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:48369 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726833AbgEQBQG (ORCPT ); Sat, 16 May 2020 21:16:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589678165; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DkMpg+DAZVobJN3z7nH0TAxZiR3oF4oJ3zndpFda8ag=; b=iaSiRWtOYjwQRzRNseQg1TFLt0j1Z+mny0K/v7LWz9/rIKE/Ncl0bs/yxBO5gz1VRcF9// 464/Mc1zfeoNJ5LcpwrAKtOsc4sNDvamRZQq3MqYDtHforV8wvrzMKgFJ+bJFBo647+Qmv kmF5OfFNfxPPYWLjNhlC7vnXgX1If3U= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-291-sw_h2SfLOCSt6ovumpljBA-1; Sat, 16 May 2020 21:15:58 -0400 X-MC-Unique: sw_h2SfLOCSt6ovumpljBA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 771F01009440; Sun, 17 May 2020 01:15:57 +0000 (UTC) Received: from llong.remote.csb (ovpn-112-26.rdu2.redhat.com [10.10.112.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id E7D805C1D6; Sun, 17 May 2020 01:15:55 +0000 (UTC) Subject: Re: "BUG: MAX_LOCKDEP_ENTRIES too low" with 6979 "&type->s_umount_key" To: Qian Cai , Peter Zijlstra , Will Deacon , Ingo Molnar Cc: David Howells , Alexander Viro , linux-fsdevel@vger.kernel.org, Linux Kernel Mailing List References: From: Waiman Long Organization: Red Hat Message-ID: Date: Sat, 16 May 2020 21:15:55 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/15/20 1:21 AM, Qian Cai wrote: > Lockdep is screwed here in next-20200514 due to "BUG: MAX_LOCKDEP_ENTRIES too low". One of the traces below pointed to this linux-next commit, > > 8c8e824d4ef0 watch_queue: Introduce a non-repeating system-unique superblock ID > > which was accidentally just showed up in next-20200514 along with, > > 46896d79c514 watch_queue: Add superblock notifications > > I did have here, > > CONFIG_SB_NOTIFICATIONS=y > CONFIG_MOUNT_NOTIFICATIONS=y > CONFIG_FSINFO=y > > While MAX_LOCKDEP_ENTRIES is 32768, I noticed there is one type of lock had a lot along, > > # grep 'type->s_umount_key’ /proc/lockdep_chains | wc -l > 6979 The lock_list table entries are for tracking a lock's forward and backward dependencies. The lockdep_chains isn't the right lockdep file to look at. Instead, check the lockdep files for entries with the maximum BD (backward dependency) + FD (forward dependency). That will give you a better view of which locks are consuming most of the lock_list entries. Also take a look at lockdep_stats for an overall view of how much various table entries are being consumed. Cheers, Longman