linux-kernel - Re: [BUG] D state process after unplug and umount usb disk

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Message-ID: <Pine.LNX.4.44L0.1109040945370.9175-100000@netrider.rowland.org>
Date:	Sun, 4 Sep 2011 09:49:26 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Lin Ming <mlin@...pku.edu.cn>
cc:	Dave Young <hidave.darkstar@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	<fengguang.wu@...el.com>, <linux-usb@...r.kernel.org>
Subject: Re: [BUG] D state process after unplug and umount usb disk

On Sun, 4 Sep 2011, Lin Ming wrote:

> On Sat, Sep 3, 2011 at 6:31 PM, Dave Young <hidave.darkstar@...il.com> wrote:
> > Hi,
> >
> > Known issue?
> >
> > Reproduce by:
> > mount /dev/sdb2 /mnt/sdb2 -t ext3
> > cat /mnt/sdb2/* >/dev/null
> > unplug usb disk
> > umount -f /mnt/sdb2
> >
> > dmesg as below:

BTW, this may or may not be related:

https://bugzilla.kernel.org/show_bug.cgi?id=25832  (kernel crashes when 
a mounted ext3/4 file system is physically removed)

> > [ 1440.567271] SysRq : Show Blocked State
> > [ 1440.567278]   task                        PC stack   pid father
> > [ 1440.567312] cat             D ffff880037a1e378  4296  2381   2310 0x00000004
> > [ 1440.567320]  ffff88003cca5838 0000000000000046 ffff88003cca57e8
> > ffffffff00000000
> > [ 1440.567332]  00000000000134c0 00000000000134c0 00000000000134c0
> > ffff880037a1e000
> > [ 1440.567339]  00000000000134c0 ffff88003cca5fd8 00000000000134c0
> > 00000000000134c0
> > [ 1440.567347] Call Trace:
> > [ 1440.567357]  [<ffffffff810c0468>] ? lock_page+0x2a/0x2a
> > [ 1440.567363]  [<ffffffff815e452d>] io_schedule+0x5e/0x79
> > [ 1440.567368]  [<ffffffff810c0471>] sleep_on_page+0x9/0xd
> > [ 1440.567373]  [<ffffffff815e4adf>] __wait_on_bit_lock+0x41/0x8a
> > [ 1440.567378]  [<ffffffff810c0437>] __lock_page+0x61/0x68
> > [ 1440.567384]  [<ffffffff81058739>] ? autoremove_wake_function+0x34/0x34
> > [ 1440.567390]  [<ffffffff8102f704>] ? should_resched+0x9/0x29
> > [ 1440.567395]  [<ffffffff810c9b0b>] lock_page+0x25/0x29
> > [ 1440.567400]  [<ffffffff810ca1ac>] truncate_inode_pages_range+0x2a6/0x32d
> > [ 1440.567406]  [<ffffffff810ca240>] truncate_inode_pages+0xd/0xf
> > [ 1440.567411]  [<ffffffff811642cf>] ext3_evict_inode+0xc9/0x1d7
> > [ 1440.567417]  [<ffffffff8111288e>] evict+0xa3/0x15e
> > [ 1440.567422]  [<ffffffff81112b34>] dispose_list+0x3d/0x49
> > [ 1440.567426]  [<ffffffff81113475>] evict_inodes+0xf1/0x100
> > [ 1440.567431]  [<ffffffff810ffd21>] generic_shutdown_super+0x47/0xc7
> > [ 1440.567436]  [<ffffffff810ffdc3>] kill_block_super+0x22/0x65
> > [ 1440.567441]  [<ffffffff811000da>] deactivate_locked_super+0x21/0x52
> > [ 1440.567445]  [<ffffffff811009ab>] deactivate_super+0x35/0x39
> > [ 1440.567452]  [<ffffffff81116395>] mntput_no_expire+0xcb/0xd0
> > [ 1440.567457]  [<ffffffff811163bb>] mntput+0x21/0x23
> > [ 1440.567461]  [<ffffffff810ff8e7>] fput+0x196/0x1a5
> > [ 1440.567467]  [<ffffffff810fc7a1>] filp_close+0x6b/0x76
> > [ 1440.567472]  [<ffffffff8103fa8a>] put_files_struct+0x73/0xd1
> > [ 1440.567477]  [<ffffffff8103fb7b>] exit_files+0x46/0x4f
> > [ 1440.567481]  [<ffffffff8103fe01>] do_exit+0x27d/0x7b3
> > [ 1440.567487]  [<ffffffff8104d97f>] ? get_signal_to_deliver+0x81/0x4ac
> > [ 1440.567493]  [<ffffffff812e5e27>] ? do_raw_spin_lock+0x6b/0x122
> > [ 1440.567497]  [<ffffffff810405c5>] do_group_exit+0x7d/0xa8
> > [ 1440.567502]  [<ffffffff8104dd8b>] get_signal_to_deliver+0x48d/0x4ac
> > [ 1440.567509]  [<ffffffff81001ea2>] do_signal+0x39/0x600
> > [ 1440.567514]  [<ffffffff810fdb37>] ? fsnotify_access+0x5d/0x65
> > [ 1440.567519]  [<ffffffff810024a4>] do_notify_resume+0x27/0x69
> > [ 1440.567524]  [<ffffffff812e158e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
> > [ 1440.567529]  [<ffffffff815ecd63>] int_signal+0x12/0x17

> Where does this exit signal come from?
> Does USB interrupt handler will send kill signal to all processes
> accessing it when it's unplugged(by hand)?

The USB stack does not send any signals at all unless a process 
specifically asks for them.

Alan Stern

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