From patchwork Tue Apr 25 11:52:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 13223246 X-Patchwork-Delegate: song@kernel.org 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 8F20FC7EE21 for ; Tue, 25 Apr 2023 11:55:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234018AbjDYLzF (ORCPT ); Tue, 25 Apr 2023 07:55:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233880AbjDYLzA (ORCPT ); Tue, 25 Apr 2023 07:55:00 -0400 Received: from dggsgout11.his.huawei.com (unknown [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A64C524C; Tue, 25 Apr 2023 04:54:43 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Q5L5W4plCz4f42rc; Tue, 25 Apr 2023 19:54:39 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgBnHbF+v0dkGEZ+IA--.20559S5; Tue, 25 Apr 2023 19:54:40 +0800 (CST) From: Yu Kuai To: logang@deltatee.com, axboe@kernel.dk, song@kernel.org Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com Subject: [PATCH -next v7 1/5] md: factor out a helper to wake up md_thread directly Date: Tue, 25 Apr 2023 19:52:52 +0800 Message-Id: <20230425115256.3663932-2-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230425115256.3663932-1-yukuai1@huaweicloud.com> References: <20230425115256.3663932-1-yukuai1@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: gCh0CgBnHbF+v0dkGEZ+IA--.20559S5 X-Coremail-Antispam: 1UD129KBjvJXoWxXFW8CF17JrW5Xr1kKF4xtFb_yoW5CFW3p3 y8tF15Wr48AFZ8ZFZrJa4vka4rZr10qFy7try3Cw4rJw1rKw43tFyS9FyjyFyDAFyrAw45 Zw15tFWruFZ2kr7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBE14x267AKxVW5JVWrJwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jr4l82xGYIkIc2 x26xkF7I0E14v26r1I6r4UM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F4UJw A2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kIc2 xKxwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v2 6r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2 Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_ Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMI IF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUqAp5UUUUU = X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org From: Yu Kuai md_wakeup_thread() can't wakeup md_thread->tsk if md_thread->run is still in progress, and in some cases md_thread->tsk need to be woke up directly, like md_set_readonly() and do_md_stop(). Commit 9dfbdafda3b3 ("md: unlock mddev before reap sync_thread in action_store") introduce a new scenario where unregister sync_thread is not protected by 'reconfig_mutex', this can cause null-ptr-deference in theroy: t1: md_set_readonly t2: action_store md_unregister_thread // 'reconfig_mutex' is not held // 'reconfig_mutex' is held by caller if (mddev->sync_thread) thread = *threadp *threadp = NULL wake_up_process(mddev->sync_thread->tsk) // null-ptr-deference This patch factor out a helper to wake up md_thread directly, so that 'sync_thread' won't be accessed multiple times from the reader side. And perhaps this helper will be used later to fix action_store(). This patch also prepare to protect md_thread with rcu. Signed-off-by: Yu Kuai --- drivers/md/md.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 8e344b4b3444..b4f482d69de3 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -92,6 +92,7 @@ static struct workqueue_struct *md_rdev_misc_wq; static int remove_and_add_spares(struct mddev *mddev, struct md_rdev *this); static void mddev_detach(struct mddev *mddev); +static void md_wakeup_thread_directly(struct md_thread *thread); enum md_ro_state { MD_RDWR, @@ -6269,10 +6270,12 @@ static int md_set_readonly(struct mddev *mddev, struct block_device *bdev) } if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) set_bit(MD_RECOVERY_INTR, &mddev->recovery); - if (mddev->sync_thread) - /* Thread might be blocked waiting for metadata update - * which will now never happen */ - wake_up_process(mddev->sync_thread->tsk); + + /* + * Thread might be blocked waiting for metadata update which will now + * never happen + */ + md_wakeup_thread_directly(mddev->sync_thread); if (mddev->external && test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) return -EBUSY; @@ -6333,10 +6336,12 @@ static int do_md_stop(struct mddev *mddev, int mode, } if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) set_bit(MD_RECOVERY_INTR, &mddev->recovery); - if (mddev->sync_thread) - /* Thread might be blocked waiting for metadata update - * which will now never happen */ - wake_up_process(mddev->sync_thread->tsk); + + /* + * Thread might be blocked waiting for metadata update which will now + * never happen + */ + md_wakeup_thread_directly(mddev->sync_thread); mddev_unlock(mddev); wait_event(resync_wait, (mddev->sync_thread == NULL && @@ -7886,6 +7891,12 @@ static int md_thread(void *arg) return 0; } +static void md_wakeup_thread_directly(struct md_thread *thread) +{ + if (thread) + wake_up_process(thread->tsk); +} + void md_wakeup_thread(struct md_thread *thread) { if (thread) {