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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1667C77B61 for ; Tue, 25 Apr 2023 08:09:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233521AbjDYIJo (ORCPT ); Tue, 25 Apr 2023 04:09:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38964 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233416AbjDYIJm (ORCPT ); Tue, 25 Apr 2023 04:09:42 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 203FEA2; Tue, 25 Apr 2023 01:09:39 -0700 (PDT) Received: from kwepemm600009.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4Q5F0w0f5GzSsln; Tue, 25 Apr 2023 16:05:20 +0800 (CST) Received: from [10.174.176.73] (10.174.176.73) by kwepemm600009.china.huawei.com (7.193.23.164) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Tue, 25 Apr 2023 16:09:35 +0800 Subject: Re: [PATCH] Remove blkg node after destroying blkg To: Tao Su , , CC: , , , "yukuai (C)" References: <20230425075911.839539-1-tao1.su@linux.intel.com> From: Yu Kuai Message-ID: Date: Tue, 25 Apr 2023 16:09:34 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20230425075911.839539-1-tao1.su@linux.intel.com> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.176.73] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemm600009.china.huawei.com (7.193.23.164) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, ÔÚ 2023/04/25 15:59, Tao Su дµÀ: > Kernel hang when poweroff or reboot, due to infinite restart in function > blkg_destroy_all. It will goto restart label when a batch of blkgs are > destroyed, but not remove blkg node in blkg_list. So the blkg_list is > same in every 'restart' and result in kernel hang. > > By adding list_del to remove blkg node after destroying, can solve this > kernel hang issue and satisfy the previous will to 'restart'. > > Reported-by: Xiangfei Ma > Tested-by: Xiangfei Ma > Tested-by: Farrah Chen > Signed-off-by: Tao Su > --- > block/blk-cgroup.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c > index bd50b55bdb61..960eb538a704 100644 > --- a/block/blk-cgroup.c > +++ b/block/blk-cgroup.c > @@ -530,6 +530,7 @@ static void blkg_destroy_all(struct gendisk *disk) > > spin_lock(&blkcg->lock); > blkg_destroy(blkg); > + list_del(&blkg->q_node); blkg should stay on the queue list until blkg_free_workfn(), otherwise parent blkg can be freed before child, which will cause some known issue. I think this hung happens when total blkg is greater than BLKG_DESTROY_BATCH_SIZE, right? Can you try if following patch fix your problem? index 1c1ebeb51003..0ecb4cce8af2 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -527,6 +527,9 @@ static void blkg_destroy_all(struct gendisk *disk) list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { struct blkcg *blkcg = blkg->blkcg; + if (hlist_unhashed(&blkg->blkcg_node)) + continue; + spin_lock(&blkcg->lock); blkg_destroy(blkg); spin_unlock(&blkcg->lock); > spin_unlock(&blkcg->lock); > > /* >