From patchwork Wed Feb 21 09:01:22 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Li Nan X-Patchwork-Id: 13565138 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 14EF33D576; Wed, 21 Feb 2024 09:07:15 +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=1708506445; cv=none; b=O78TAYCRh69oZIy+LQJudGI10j7Fe/rXGtQ9a6oGcaSQlf6Gn2wTppcLXyq0lshY/plvLhVlT795BJg08hBXeSmiZTS97rg5Fa5DYSW9D1IkUzvYKCVQ8H5ZNl0An71HkTKtwlBJb/LTU3k4lPQC5kmapxaQJl08A+L3Wr2G/PQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708506445; c=relaxed/simple; bh=YYB5LvmnN6Hst4z0XRzNTIaIeLr1z5XlifL/wMlc+bo=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=QgaFjnS929WYrvAqRIGPUbkTHb/6JmFnl3fiowSgxhGBMxcdhVVnkOTfnk0HWvT7Bn3pOlSONXbbXT3sJJWenmC4zY/Sxziw9IaSJbRiZD00/SWVSX5vu/2j7Gw5pvU/GHNa7hYZGqIoVjZ1Lu3dBdCq1HIuwAQmQ5pY3cJmsYo= 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 [172.19.163.235]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4Tfr4d34rCz4f3jdL; Wed, 21 Feb 2024 17:06:57 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.112]) by mail.maildlp.com (Postfix) with ESMTP id 653541A0568; Wed, 21 Feb 2024 17:07:02 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP1 (Coremail) with SMTP id cCh0CgDHlxAsvdVlKPi+Eg--.18486S4; Wed, 21 Feb 2024 17:06:54 +0800 (CST) From: linan666@huaweicloud.com To: axboe@kernel.dk, song@kernel.org, yukuai3@huawei.com Cc: linux-raid@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linan666@huaweicloud.com, yi.zhang@huawei.com, houtao1@huawei.com, yangerkun@huawei.com Subject: [PATCH v2] block: fix deadlock between bd_link_disk_holder and partition scan Date: Wed, 21 Feb 2024 17:01:22 +0800 Message-Id: <20240221090122.1281868-1-linan666@huaweicloud.com> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: cCh0CgDHlxAsvdVlKPi+Eg--.18486S4 X-Coremail-Antispam: 1UD129KBjvJXoWxZFy8KF45WF43KryfXFyftFb_yoW5uF48pF Z8KFWktry8tF4DuF4Dt3y7ur4UKw18Wa1xJr97KrWS9rZrAr4v9Fy2yFy7uFy8KrWIyFWD tF1UX3yYva10k3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBj14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1lnxkEFVAIw20F6cxK64vIFxWle2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xv F2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r 4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I 648v4I1lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lw4CEc2x0rVAKj4xxMxAIw28IcxkI7VAKI4 8JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xv wVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjx v20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20E Y4v20xvaj40_WFyUJVCq3wCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I 0E14v26r1j6r4UYxBIdaVFxhVjvjDU0xZFpf9x0JUBSoJUUUUU= 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 'blk_holder_mutex' to replace 'open_mutex'. Fixes: 1b0a2d950ee2 ("md: use new apis to suspend array for ioctls involed array reconfiguration") Reported-by: mgperkow@gmail.com Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218459 Signed-off-by: Li Nan Reviewed-by: Yu Kuai Reviewed-by: Christoph Hellwig --- v2: add a blk_ prefix to 'holder_mutex'. block/holder.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/block/holder.c b/block/holder.c index 37d18c13d958..791091a7eac2 100644 --- a/block/holder.c +++ b/block/holder.c @@ -8,6 +8,8 @@ struct bd_holder_disk { int refcnt; }; +static DEFINE_MUTEX(blk_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(&blk_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(&blk_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(&blk_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(&blk_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(&blk_holder_mutex); } EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);