From patchwork Fri Mar 9 12:59:06 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maurizio Lombardi X-Patchwork-Id: 10270551 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D18D260236 for ; Fri, 9 Mar 2018 12:59:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C7B5729D85 for ; Fri, 9 Mar 2018 12:59:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BBA2029DD7; Fri, 9 Mar 2018 12:59:11 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2F84F29D85 for ; Fri, 9 Mar 2018 12:59:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751146AbeCIM7J (ORCPT ); Fri, 9 Mar 2018 07:59:09 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:32966 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751059AbeCIM7I (ORCPT ); Fri, 9 Mar 2018 07:59:08 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E30B68D746; Fri, 9 Mar 2018 12:59:07 +0000 (UTC) Received: from manaslu.brq.redhat.com (unknown [10.43.2.45]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6AE5C2026609; Fri, 9 Mar 2018 12:59:07 +0000 (UTC) From: Maurizio Lombardi To: axboe@kernel.dk Cc: linux-scsi@vger.kernel.org Subject: [PATCH] cdrom: do not call check_disk_change() inside cdrom_open() Date: Fri, 9 Mar 2018 13:59:06 +0100 Message-Id: <1520600346-1074-1-git-send-email-mlombard@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 09 Mar 2018 12:59:07 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 09 Mar 2018 12:59:07 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'mlombard@redhat.com' RCPT:'' Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP when mounting an ISO filesystem sometimes (very rarely) the system hangs because of a race condition between two tasks. PID: 6766 TASK: ffff88007b2a6dd0 CPU: 0 COMMAND: "mount" #0 [ffff880078447ae0] __schedule at ffffffff8168d605 #1 [ffff880078447b48] schedule_preempt_disabled at ffffffff8168ed49 #2 [ffff880078447b58] __mutex_lock_slowpath at ffffffff8168c995 #3 [ffff880078447bb8] mutex_lock at ffffffff8168bdef #4 [ffff880078447bd0] sr_block_ioctl at ffffffffa00b6818 [sr_mod] #5 [ffff880078447c10] blkdev_ioctl at ffffffff812fea50 #6 [ffff880078447c70] ioctl_by_bdev at ffffffff8123a8b3 #7 [ffff880078447c90] isofs_fill_super at ffffffffa04fb1e1 [isofs] #8 [ffff880078447da8] mount_bdev at ffffffff81202570 #9 [ffff880078447e18] isofs_mount at ffffffffa04f9828 [isofs] #10 [ffff880078447e28] mount_fs at ffffffff81202d09 #11 [ffff880078447e70] vfs_kern_mount at ffffffff8121ea8f #12 [ffff880078447ea8] do_mount at ffffffff81220fee #13 [ffff880078447f28] sys_mount at ffffffff812218d6 #14 [ffff880078447f80] system_call_fastpath at ffffffff81698c49 RIP: 00007fd9ea914e9a RSP: 00007ffd5d9bf648 RFLAGS: 00010246 RAX: 00000000000000a5 RBX: ffffffff81698c49 RCX: 0000000000000010 RDX: 00007fd9ec2bc210 RSI: 00007fd9ec2bc290 RDI: 00007fd9ec2bcf30 RBP: 0000000000000000 R8: 0000000000000000 R9: 0000000000000010 R10: 00000000c0ed0001 R11: 0000000000000206 R12: 00007fd9ec2bc040 R13: 00007fd9eb6b2380 R14: 00007fd9ec2bc210 R15: 00007fd9ec2bcf30 ORIG_RAX: 00000000000000a5 CS: 0033 SS: 002b This task was trying to mount the cdrom. It allocated and configured a super_block struct and owned the write-lock for the super_block->s_umount rwsem. While exclusively owning the s_umount lock, it called sr_block_ioctl and waited to acquire the global sr_mutex lock. PID: 6785 TASK: ffff880078720fb0 CPU: 0 COMMAND: "systemd-udevd" #0 [ffff880078417898] __schedule at ffffffff8168d605 #1 [ffff880078417900] schedule at ffffffff8168dc59 #2 [ffff880078417910] rwsem_down_read_failed at ffffffff8168f605 #3 [ffff880078417980] call_rwsem_down_read_failed at ffffffff81328838 #4 [ffff8800784179d0] down_read at ffffffff8168cde0 #5 [ffff8800784179e8] get_super at ffffffff81201cc7 #6 [ffff880078417a10] __invalidate_device at ffffffff8123a8de #7 [ffff880078417a40] flush_disk at ffffffff8123a94b #8 [ffff880078417a88] check_disk_change at ffffffff8123ab50 #9 [ffff880078417ab0] cdrom_open at ffffffffa00a29e1 [cdrom] #10 [ffff880078417b68] sr_block_open at ffffffffa00b6f9b [sr_mod] #11 [ffff880078417b98] __blkdev_get at ffffffff8123ba86 #12 [ffff880078417bf0] blkdev_get at ffffffff8123bd65 #13 [ffff880078417c78] blkdev_open at ffffffff8123bf9b #14 [ffff880078417c90] do_dentry_open at ffffffff811fc7f7 #15 [ffff880078417cd8] vfs_open at ffffffff811fc9cf #16 [ffff880078417d00] do_last at ffffffff8120d53d #17 [ffff880078417db0] path_openat at ffffffff8120e6b2 #18 [ffff880078417e48] do_filp_open at ffffffff8121082b #19 [ffff880078417f18] do_sys_open at ffffffff811fdd33 #20 [ffff880078417f70] sys_open at ffffffff811fde4e #21 [ffff880078417f80] system_call_fastpath at ffffffff81698c49 RIP: 00007f29438b0c20 RSP: 00007ffc76624b78 RFLAGS: 00010246 RAX: 0000000000000002 RBX: ffffffff81698c49 RCX: 0000000000000000 RDX: 00007f2944a5fa70 RSI: 00000000000a0800 RDI: 00007f2944a5fa70 RBP: 00007f2944a5f540 R8: 0000000000000000 R9: 0000000000000020 R10: 00007f2943614c40 R11: 0000000000000246 R12: ffffffff811fde4e R13: ffff880078417f78 R14: 000000000000000c R15: 00007f2944a4b010 ORIG_RAX: 0000000000000002 CS: 0033 SS: 002b This task tried to open the cdrom device, the sr_block_open function acquired the global sr_mutex lock. The call to check_disk_change() then saw an event flag indicating a possible media change and tried to flush any cached data for the device. As part of the flush, it tried to acquire the super_block->s_umount lock associated with the cdrom device. This was the same super_block as created and locked by the previous task. The first task acquires the s_umount lock and then the sr_mutex_lock; the second task acquires the sr_mutex_lock and then the s_umount lock. This patch fixes the issue by moving check_disk_change() out of cdrom_open() and let the caller take care of it. Signed-off-by: Maurizio Lombardi --- drivers/block/paride/pcd.c | 2 ++ drivers/cdrom/cdrom.c | 3 --- drivers/cdrom/gdrom.c | 3 +++ drivers/ide/ide-cd.c | 2 ++ drivers/scsi/sr.c | 2 ++ 5 files changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/block/paride/pcd.c b/drivers/block/paride/pcd.c index 7b8c636..a026211 100644 --- a/drivers/block/paride/pcd.c +++ b/drivers/block/paride/pcd.c @@ -230,6 +230,8 @@ static int pcd_block_open(struct block_device *bdev, fmode_t mode) struct pcd_unit *cd = bdev->bd_disk->private_data; int ret; + check_disk_change(bdev); + mutex_lock(&pcd_mutex); ret = cdrom_open(&cd->info, bdev, mode); mutex_unlock(&pcd_mutex); diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c index e36d160..8327478 100644 --- a/drivers/cdrom/cdrom.c +++ b/drivers/cdrom/cdrom.c @@ -1152,9 +1152,6 @@ int cdrom_open(struct cdrom_device_info *cdi, struct block_device *bdev, cd_dbg(CD_OPEN, "entering cdrom_open\n"); - /* open is event synchronization point, check events first */ - check_disk_change(bdev); - /* if this was a O_NONBLOCK open and we should honor the flags, * do a quick open without drive/disc integrity checks. */ cdi->use_count++; diff --git a/drivers/cdrom/gdrom.c b/drivers/cdrom/gdrom.c index 6495b03f..ae3a753 100644 --- a/drivers/cdrom/gdrom.c +++ b/drivers/cdrom/gdrom.c @@ -497,6 +497,9 @@ static int gdrom_audio_ioctl(struct cdrom_device_info *cdi, unsigned int cmd, static int gdrom_bdops_open(struct block_device *bdev, fmode_t mode) { int ret; + + check_disk_change(bdev); + mutex_lock(&gdrom_mutex); ret = cdrom_open(gd.cd_info, bdev, mode); mutex_unlock(&gdrom_mutex); diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c index 7c3ed7c..5613cc2 100644 --- a/drivers/ide/ide-cd.c +++ b/drivers/ide/ide-cd.c @@ -1613,6 +1613,8 @@ static int idecd_open(struct block_device *bdev, fmode_t mode) struct cdrom_info *info; int rc = -ENXIO; + check_disk_change(bdev); + mutex_lock(&ide_cd_mutex); info = ide_cd_get(bdev->bd_disk); if (!info) diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c index 9be34d3..0cf25d7 100644 --- a/drivers/scsi/sr.c +++ b/drivers/scsi/sr.c @@ -525,6 +525,8 @@ static int sr_block_open(struct block_device *bdev, fmode_t mode) struct scsi_cd *cd; int ret = -ENXIO; + check_disk_change(bdev); + mutex_lock(&sr_mutex); cd = scsi_cd_get(bdev->bd_disk); if (cd) {