From patchwork Wed Feb 7 09:27:56 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Li Nan X-Patchwork-Id: 13548236 Received: from dggsgout12.his.huawei.com (unknown [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4EACF20DFA; Wed, 7 Feb 2024 09:32:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707298374; cv=none; b=tzSbRHUNkc1Gt9RoQYIC8V/T+mAZPCsMXqTClxtPUqLkhRzZq/62pM8wIygUQfTUlSB+yIheLTS+iit2Aj+RepSdAXSRDNcVmfF/amB8gNjphF0DG7VNDFPNKQaIoTBjsxbdIpaIaxLi5cGHlwTGff9ibmFIaxcYES/A0i301hM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707298374; c=relaxed/simple; bh=7u+z3q+4Hs3vIsnTCgfHn67LCKeRoHsrK3+hSZEaDt0=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=kHfmuE0nCQe9eIW5fU+oYG2Wgo9bSpVVlAOVuqadVQI0gaGRrh1paPv1OW5UxHQTeM8dKEofRixX6UBz9hhOh916lI122Cr9a3cGTpAwjUo14YIXI0uWFCPh4HZ6VWW7zCcx+JXcM4PgJ9hz4OZLeJxu4vtJHo8GQ6BcCFps58Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4TVFJh5RQmz4f3jsm; Wed, 7 Feb 2024 17:32:36 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id 394401A0A9A; Wed, 7 Feb 2024 17:32:41 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP1 (Coremail) with SMTP id cCh0CgDHlxA3TsNl4_n7DA--.43370S4; Wed, 07 Feb 2024 17:32:41 +0800 (CST) From: linan666@huaweicloud.com To: axboe@kernel.dk Cc: linux-raid@vger.kernel.org, song@kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linan666@huaweicloud.com, yukuai3@huawei.com, yi.zhang@huawei.com, houtao1@huawei.com, yangerkun@huawei.com Subject: [PATCH] block: fix deadlock between bd_link_disk_holder and partition scan Date: Wed, 7 Feb 2024 17:27:56 +0800 Message-Id: <20240207092756.2087888-1-linan666@huaweicloud.com> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: cCh0CgDHlxA3TsNl4_n7DA--.43370S4 X-Coremail-Antispam: 1UD129KBjvJXoWxZFy8KF45WF43KryfWr4rKrg_yoW5Cr4fpF Z0gFZ7try8ta1Dur4Dt3y7Zr4UKw18Wa1xJr97KFy29rZrArs29r12yFy7uFy8KrWIyF4D tF1UX3yYvF40k3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9E14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4j 6r4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAac4AC62xK8xCEY4vEwIxC4wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC 0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr 1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IE rcIFxwACI402YVCY1x02628vn2kIc2xKxwAKzVCY07xG64k0F24l42xK82IYc2Ij64vIr4 1l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK 67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI 8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK8VAv wI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxV AFwI0_Jr0_GrUvcSsGvfC2KfnxnUUI43ZEXa7VUbSApUUUUUU== X-CM-SenderInfo: polqt0awwwqx5xdzvxpfor3voofrz/ From: Li Nan 'open_mutex' of gendisk is used to protect open/close block devices. But in bd_link_disk_holder(), it is used to protect the creation of symlink between holding disk and slave bdev, which introduces some issues. When bd_link_disk_holder() is called, the driver is usually in the process of initialization/modification and may suspend submitting io. At this time, any io hold 'open_mutex', such as scanning partitions, can cause deadlocks. For example, in raid: T1 T2 bdev_open_by_dev lock open_mutex [1] ... efi_partition ... md_submit_bio md_ioctl mddev_syspend -> suspend all io md_add_new_disk bind_rdev_to_array bd_link_disk_holder try lock open_mutex [2] md_handle_request -> wait mddev_resume T1 scan partition, T2 add a new device to raid. T1 waits for T2 to resume mddev, but T2 waits for open_mutex held by T1. Deadlock occurs. Fix it by introducing a local mutex 'holder_mutex' to replace 'open_mutex'. Signed-off-by: Li Nan --- block/holder.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/block/holder.c b/block/holder.c index 37d18c13d958..5bfb0a674cc7 100644 --- a/block/holder.c +++ b/block/holder.c @@ -8,6 +8,8 @@ struct bd_holder_disk { int refcnt; }; +static DEFINE_MUTEX(holder_mutex); + static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev, struct gendisk *disk) { @@ -80,7 +82,7 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) kobject_get(bdev->bd_holder_dir); mutex_unlock(&bdev->bd_disk->open_mutex); - mutex_lock(&disk->open_mutex); + mutex_lock(&holder_mutex); WARN_ON_ONCE(!bdev->bd_holder); holder = bd_find_holder_disk(bdev, disk); @@ -108,7 +110,7 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) goto out_del_symlink; list_add(&holder->list, &disk->slave_bdevs); - mutex_unlock(&disk->open_mutex); + mutex_unlock(&holder_mutex); return 0; out_del_symlink: @@ -116,7 +118,7 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) out_free_holder: kfree(holder); out_unlock: - mutex_unlock(&disk->open_mutex); + mutex_unlock(&holder_mutex); if (ret) kobject_put(bdev->bd_holder_dir); return ret; @@ -140,7 +142,7 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk) if (WARN_ON_ONCE(!disk->slave_dir)) return; - mutex_lock(&disk->open_mutex); + mutex_lock(&holder_mutex); holder = bd_find_holder_disk(bdev, disk); if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) { del_symlink(disk->slave_dir, bdev_kobj(bdev)); @@ -149,6 +151,6 @@ void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk) list_del_init(&holder->list); kfree(holder); } - mutex_unlock(&disk->open_mutex); + mutex_unlock(&holder_mutex); } EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);