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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FAKE_REPLY_C,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 2E002C433E1 for ; Wed, 15 Jul 2020 13:49:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0AD1D20656 for ; Wed, 15 Jul 2020 13:49:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chrisdown.name header.i=@chrisdown.name header.b="HMX8H/+V" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729411AbgGONtf (ORCPT ); Wed, 15 Jul 2020 09:49:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45182 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729086AbgGONte (ORCPT ); Wed, 15 Jul 2020 09:49:34 -0400 Received: from mail-ej1-x641.google.com (mail-ej1-x641.google.com [IPv6:2a00:1450:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 554BBC061755 for ; Wed, 15 Jul 2020 06:49:34 -0700 (PDT) Received: by mail-ej1-x641.google.com with SMTP id a1so2209473ejg.12 for ; Wed, 15 Jul 2020 06:49:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chrisdown.name; s=google; h=date:from:to:cc:subject:message-id:mime-version:content-disposition :in-reply-to:user-agent; bh=zeViOh2orgG60XFzN87odItB31rTFkAqEDgeYYexRbU=; b=HMX8H/+VSPb0AWs/HTx8iR768QkR1c9tvZftaQegAfNxCbqdkHTEaDz2QXG2OL8cXM f/C0NWyHazgGXOivIGw+5/O/ZvvH0J51ycLQKkdYdTlB2OblB+4lXAik/kUvaVnShacb 7DfNoKobfxFYZpTEHQblKFCKJwEahj6gOe0Zg= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition:in-reply-to:user-agent; bh=zeViOh2orgG60XFzN87odItB31rTFkAqEDgeYYexRbU=; b=tirdku1w+oGfyaC1oKzRESuQ1GTcakP3UEcEgA5kkouGgtCdPWXOGdZN//uTmgQvVN BUVCK5Qdry+DKskkGcailHpvYpaKHWziLXTqPVlc1H9mdg62KvgF6o8xIYNAoWEPIi2K 7b1ITQz1yIcG3A9cEku5OZnsvIXCFkCB2URMIEbijTOw84KBVHzVvnpjiv7K8TTixDEf EQZ9+AUN/q8lAoMFendnkf+4OsN7xD64dmlBZf7WV8QipoFh8t03/y75JxI8ER+VDUpf NucBge8kSDhXec6plxta2iU8ENue5+olgbnqxCGmnOT+cw8dHioUaeEtOLAQ9AcjZj4l oLww== X-Gm-Message-State: AOAM530rgOpIjfM0QyyzMBEoJcWzszZuJyGiEgRNfiozFY2YgiSGgU6y zWsQxA3TWDFBhPLvVtCWqKbqyw== X-Google-Smtp-Source: ABdhPJwZnF/x41ajJsrab8AP8TGY2hx8AqSI8JdB3MCIjndyFlBsXgYmbocbNOq1qkY8a0m27vepRQ== X-Received: by 2002:a17:906:a459:: with SMTP id cb25mr9226346ejb.234.1594820972892; Wed, 15 Jul 2020 06:49:32 -0700 (PDT) Received: from localhost ([2620:10d:c093:400::5:a5b1]) by smtp.gmail.com with ESMTPSA id e8sm2124878eja.101.2020.07.15.06.49.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jul 2020 06:49:32 -0700 (PDT) Date: Wed, 15 Jul 2020 14:49:31 +0100 From: Chris Down To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH v2 2/2] btrfs: qgroup: add sysfs interface for debug Message-ID: <20200715134931.GA2140@chrisdown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200628050715.60961-3-wqu@suse.com> User-Agent: Mutt/1.14.6 (2020-07-11) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Hi Wenruo, While testing my pending patches on top of linux-next, I encountered a bug that seems related to this patch during btrfs unmount. Specifically, a null pointer dereference in kobject_del inside btrfs_sysfs_del_qgroups from close_ctree. The fix may be as simple as checking if the kobject is initialised, although perhaps it should always be initialised in this case, so I'll leave you to work out what the real issue is :-) RIP: kobject_del+0x1/0x20 [...] Call Trace: btrfs_sysfs_del_qgroups+0xa5/0xe0 close_ctree+0x1cd/0x2c0 generic_shutdown_super+0x6c/0x100 kill_anon_super+0x14/0x30 btrfs_kill_super+0x12/0x20 deactivate_locked_super+0x36/0x90 cleanup_mnt+0x12d/0x190 task_work_run+0x5c/0x90 __prepare_exit_to_usermode+0x164/0x170 [...] Thanks, Chris