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 239D3C43217 for ; Thu, 1 Dec 2022 10:23:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229988AbiLAKXs (ORCPT ); Thu, 1 Dec 2022 05:23:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230380AbiLAKXd (ORCPT ); Thu, 1 Dec 2022 05:23:33 -0500 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2EA7C97923; Thu, 1 Dec 2022 02:23:19 -0800 (PST) Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4NNBwy3q3Gz4f3mSw; Thu, 1 Dec 2022 18:23:14 +0800 (CST) Received: from [10.174.176.73] (unknown [10.174.176.73]) by APP1 (Coremail) with SMTP id cCh0CgBHO6qUgIhjvN6HBQ--.58718S3; Thu, 01 Dec 2022 18:23:17 +0800 (CST) Subject: Re: [PATCH -next v2 8/9] block: fix null-pointer dereference in ioc_pd_init To: Tejun Heo , Yu Kuai Cc: Li Nan , josef@toxicpanda.com, axboe@kernel.dk, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, "yukuai (C)" References: <20221130132156.2836184-1-linan122@huawei.com> <20221130132156.2836184-9-linan122@huawei.com> <9ca2b7ab-7fd3-a9a3-12a6-021a78886b54@huaweicloud.com> From: Yu Kuai Message-ID: <431dcb3f-4572-7fd0-9e5d-90b6c34d577c@huaweicloud.com> Date: Thu, 1 Dec 2022 18:23:16 +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: Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID: cCh0CgBHO6qUgIhjvN6HBQ--.58718S3 X-Coremail-Antispam: 1UD129KBjvdXoWrZry3Jw43Ww4rKF4kZF1kXwb_yoWkGwb_uw 4vvw10kw15Ga97A3ZIyF4xXrWvgrs5Jr47X39IgFWfWr9YkasxWFZrZry3WFW5K3WI93Wa kr1DGry5W3y29jkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUb3AFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k26cxKx2IYs7xG 6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8w A2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Cr0_ Gr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s 0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xII jxv20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr 1lF7xvr2IY64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7M4IIrI8v6xkF7I0E8cxan2IY 04v7Mxk0xIA0c2IEe2xFo4CEbIxvr21l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7 v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF 1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIx AIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWrJr0_WFyU JwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCT nIWIevJa73UjIFyTuYvjfUF9a9DUUUU X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, ÔÚ 2022/12/01 18:11, Tejun Heo дµÀ: > On Thu, Dec 01, 2022 at 10:12:13AM +0800, Yu Kuai wrote: >> 1) By mentioning that "del_gendisk() is quiescing the queue", do you >> suggest to add rcu_read_lock()? This seems wrong because blk_iocost_init >> requires memory allocation. > > Quiescing uses SRCU so that should be fine but I'm not sure whether this is > the right one to piggyback on. Jens should have a better idea. > > Thanks. > Currently SRCU is used if BLK_MQ_F_BLOCKING set, otherwise RCU is used. dispatch: #define __blk_mq_run_dispatch_ops(q, check_sleep, dispatch_ops) \ do { \ if ((q)->tag_set->flags & BLK_MQ_F_BLOCKING) { \ int srcu_idx; \ \ might_sleep_if(check_sleep); \ srcu_idx = srcu_read_lock((q)->tag_set->srcu); \ (dispatch_ops); \ srcu_read_unlock((q)->tag_set->srcu, srcu_idx); \ } else { \ rcu_read_lock(); \ (dispatch_ops); \ rcu_read_unlock(); \ } \ } while (0) quiesce: void blk_mq_wait_quiesce_done(struct blk_mq_tag_set *set) { if (set->flags & BLK_MQ_F_BLOCKING) synchronize_srcu(set->srcu); else synchronize_rcu(); } Thanks, Kuai