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=-12.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 96E06C4338F for ; Tue, 17 Aug 2021 10:18:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7506260232 for ; Tue, 17 Aug 2021 10:18:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235204AbhHQKSz (ORCPT ); Tue, 17 Aug 2021 06:18:55 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:54874 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236486AbhHQKSz (ORCPT ); Tue, 17 Aug 2021 06:18:55 -0400 Received: from fsav415.sakura.ne.jp (fsav415.sakura.ne.jp [133.242.250.114]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 17HAI8C7041403; Tue, 17 Aug 2021 19:18:08 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav415.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav415.sakura.ne.jp); Tue, 17 Aug 2021 19:18:08 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav415.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 17HAI8V2041399 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Tue, 17 Aug 2021 19:18:08 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [PATCH v3] block: genhd: don't call probe function with major_names_lock held To: Hillf Danton Cc: Christoph Hellwig , Greg KH , Desmond Cheong Zhi Xi , linux-kernel@vger.kernel.org, linux-block References: <4e153910-bf60-2cca-fa02-b46d22b6e2c5@i-love.sakura.ne.jp> <20210816073313.GA27275@lst.de> <20210817081045.3609-1-hdanton@sina.com> From: Tetsuo Handa Message-ID: <3cf9d371-50e4-76a0-4024-64eca22befdf@i-love.sakura.ne.jp> Date: Tue, 17 Aug 2021 19:18:09 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210817081045.3609-1-hdanton@sina.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2021/08/17 17:10, Hillf Danton wrote: > See if it is safe to kfree(lo) after removing it from idr, with the > deadlock dissolved. It is not safe to call loop_remove() after idr_remove(). Please see HIDDEN_LOOP_DEVICE magic in "[PATCH] loop: break loop_ctl_mutex into loop_idr_spinlock and loop_removal_mutex". > > --- x/drivers/block/loop.c > +++ y/drivers/block/loop.c > @@ -2459,7 +2459,9 @@ static int loop_control_remove(int idx) > mutex_unlock(&lo->lo_mutex); > > idr_remove(&loop_index_idr, lo->lo_number); > + mutex_unlock(&loop_ctl_mutex); > loop_remove(lo); > + return 0; > out_unlock_ctrl: > mutex_unlock(&loop_ctl_mutex); > return ret; > -- > "[PATCH] loop: break loop_ctl_mutex into loop_idr_spinlock and loop_removal_mutex" can be a further improvement after "[PATCH v3] block: genhd: don't call probe function with major_names_lock held". I really would like to apply "[PATCH v3] block: genhd: don't call probe function with major_names_lock held" first.