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Subject: Re: Kernel v4.3 - RCU hang, USB implicated
From: Oliver Neukum <oneukum@suse.com>
To: Ilia Mirkin <imirkin@alum.mit.edu>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-usb@vger.kernel.org
Date: Tue, 17 Nov 2015 10:41:27 +0100
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On Mon, 2015-11-16 at 12:30 -0500, Ilia Mirkin wrote:
> Task dump for CPU 2:
> kworker/2:2     R  running task    13152 23226      2 0x00000000
> Workqueue: usb_hub_wq hub_event
>  ffff88017fd3ba08 ffff88017fd3b9c8 ffffffff8111dfc8 0000000000000002
>  ffff88017fd3ba08 ffff88017fd3b9e0 ffffffff8111fd39 0000000000000002
>  ffff88017fd3ba30 ffffffff81146727 ffff880100000000 ffff880225e62580
> Call Trace:
>  [<ffffffff8111dfc8>] sched_show_task+0xc8/0x130
>  [<ffffffff8111fd39>] dump_cpu_task+0x39/0x40
>  [<ffffffff81146727>] synchronize_sched_expedited_wait.constprop.64
> +0x1f7/0x220
>  [<ffffffff8112d420>] ? wait_woken+0x80/0x80
>  [<ffffffff81146945>] synchronize_sched_expedited+0x1f5/0x2e0
>  [<ffffffff81146a3e>] synchronize_rcu_expedited+0xe/0x10
>  [<ffffffff811c8eaf>] bdi_unregister+0x4f/0x100
>  [<ffffffff813a6fff>] blk_cleanup_queue+0xef/0x120
>  [<ffffffff815c79b4>] __scsi_remove_device+0x54/0xd0
>  [<ffffffff815c6060>] scsi_forget_host+0x60/0x70
>  [<ffffffff815bb947>] scsi_remove_host+0x77/0x110

Hi,

this looks like the SCSI layer is involved at that point.
Could you repost with a CC to linux-scsi?

	Regards
		Oliver

>  [<ffffffff81661629>] usb_stor_disconnect+0x59/0xc0
>  [<ffffffff8162c723>] usb_unbind_interface+0x83/0x270
>  [<ffffffff8159a8e6>] __device_release_driver+0x96/0x130
>  [<ffffffff8159a9a3>] device_release_driver+0x23/0x30
>  [<ffffffff81599a88>] bus_remove_device+0xf8/0x140
>  [<ffffffff81596499>] device_del+0x139/0x270
>  [<ffffffff81630c1f>] ? usb_remove_ep_devs+0x1f/0x30
>  [<ffffffff8162a270>] usb_disable_device+0xa0/0x1f0
>  [<ffffffff81621767>] usb_disconnect+0x87/0x230
>  [<ffffffff8162196a>] hub_quiesce+0x5a/0xb0
>  [<ffffffff8162310f>] hub_event+0x33f/0x1180
>  [<ffffffff81127731>] ? pick_next_task_fair+0xa1/0x970
>  [<ffffffff8110dd2c>] process_one_work+0x14c/0x3d0
>  [<ffffffff8110e2cb>] worker_thread+0x4b/0x440
>  [<ffffffff818b9f15>] ? __schedule+0x335/0x8e0
>  [<ffffffff8110e280>] ? rescuer_thread+0x2d0/0x2d0
>  [<ffffffff8110e280>] ? rescuer_thread+0x2d0/0x2d0
>  [<ffffffff81112e39>] kthread+0xc9/0xe0
>  [<ffffffff81112d70>] ? kthread_park+0x60/0x60
>  [<ffffffff818be1af>] ret_from_fork+0x3f/0x70
>  [<ffffffff81112d70>] ? kthread_park+0x60/0x60


-- 
Oliver Neukum <oneukum@suse.com>