From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932445AbcFIQfj (ORCPT <rfc822;w@1wt.eu>);
	Thu, 9 Jun 2016 12:35:39 -0400
Received: from mail.kernel.org ([198.145.29.136]:46274 "EHLO mail.kernel.org"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S932089AbcFIQfe (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Thu, 9 Jun 2016 12:35:34 -0400
Date: Thu, 9 Jun 2016 09:35:30 -0700
From: Shaohua Li <shli@kernel.org>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] md: use a mutex to protect a global list
Message-ID: <20160609163530.GA16840@kernel.org>
References: <1465402816-10882-1-git-send-email-xiyou.wangcong@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1465402816-10882-1-git-send-email-xiyou.wangcong@gmail.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Jun 08, 2016 at 09:20:16AM -0700, Cong Wang wrote:
> We saw a list corruption in the list all_detected_devices:
> 
>  WARNING: CPU: 16 PID: 226 at lib/list_debug.c:29 __list_add+0x3c/0xa9()
>  list_add corruption. next->prev should be prev (ffff880859d58320), but was ffff880859ce74c0. (next=ffffffff81abfdb0).
>  Modules linked in: ahci libahci libata sd_mod scsi_mod
>  CPU: 16 PID: 226 Comm: kworker/u241:4 Not tainted 4.1.20 #1
>  Hardware name: Dell Inc. PowerEdge C6220/04GD66, BIOS 2.2.3 11/07/2013
>  Workqueue: events_unbound async_run_entry_fn
>   0000000000000000 ffff880859a5baf8 ffffffff81502872 ffff880859a5bb48
>   0000000000000009 ffff880859a5bb38 ffffffff810692a5 ffff880859ee8828
>   ffffffff812ad02c ffff880859d58320 ffffffff81abfdb0 ffff880859eb90c0
>  Call Trace:
>   [<ffffffff81502872>] dump_stack+0x4d/0x63
>   [<ffffffff810692a5>] warn_slowpath_common+0xa1/0xbb
>   [<ffffffff812ad02c>] ? __list_add+0x3c/0xa9
>   [<ffffffff81069305>] warn_slowpath_fmt+0x46/0x48
>   [<ffffffff812ad02c>] __list_add+0x3c/0xa9
>   [<ffffffff81406f28>] md_autodetect_dev+0x41/0x62
>   [<ffffffff81285862>] rescan_partitions+0x25f/0x29d
>   [<ffffffff81506372>] ? mutex_lock+0x13/0x31
>   [<ffffffff811a090f>] __blkdev_get+0x1aa/0x3cd
>   [<ffffffff811a0b91>] blkdev_get+0x5f/0x294
>   [<ffffffff81377ceb>] ? put_device+0x17/0x19
>   [<ffffffff8128227c>] ? disk_put_part+0x12/0x14
>   [<ffffffff812836f3>] add_disk+0x29d/0x407
>   [<ffffffff81384345>] ? __pm_runtime_use_autosuspend+0x5c/0x64
>   [<ffffffffa004a724>] sd_probe_async+0x115/0x1af [sd_mod]
>   [<ffffffff81083177>] async_run_entry_fn+0x72/0x12c
>   [<ffffffff8107c44c>] process_one_work+0x198/0x2ce
>   [<ffffffff8107cac7>] worker_thread+0x1dd/0x2bb
>   [<ffffffff8107c8ea>] ? cancel_delayed_work_sync+0x15/0x15
>   [<ffffffff8107c8ea>] ? cancel_delayed_work_sync+0x15/0x15
>   [<ffffffff81080d9c>] kthread+0xae/0xb6
>   [<ffffffff81080000>] ? param_array_set+0x40/0xfa
>   [<ffffffff81080cee>] ? __kthread_parkme+0x61/0x61
>   [<ffffffff81508152>] ret_from_fork+0x42/0x70
>   [<ffffffff81080cee>] ? __kthread_parkme+0x61/0x61
> 
> I suspect it is because there is no lock protecting this
> global list, autostart_arrays() is called in ioctl() path
> where there is no lock.
> 
> Cc: Shaohua Li <shli@kernel.org>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>

Applied, thanks! This probably is because deiver can do async probe now.