Hung CIFS driver

["ISHIKAWA,chiaki" <ishikawa-FORCTJUUkgPbmG5+kqVDhQ@public.gmane.org>]

(2013/11/09 2:09), ISHIKAWA,chiaki wrote:
>
> In my next e-mail, I will report that
> under Debian GNU/Linux 64bits, the CIFS driver
> (uname -r shows 3.10-3-amd64)
> can get hung, after a network error simulation by disabling
> network interface and enabling again.
> CIFS connection is reset, but a process gets stuck in I/O state
> ("D" in ps output), and cannot be killed.
>

System: Debian GNU/Linux 64-bits running in a VMPlayer hosted on Win7.

Remote host: Win7 (the host)

Test: CIFS-share is mounted

mount.cifs //192.168.0.112/L-temp /tmp/L-temp/ -o username=myid,noperm

and under that mounted directory, the following test is performed.

/tmp/L-temp is where CIFS-share is mounted.

TEST SCRIPT:
Below,
|cp-test| is a program that copies bytes from a file to the other using
read/write system calls. (I can post a source on request.)

The test script is this:

# big-file is a 26+MiB file.
TDIR=/tmp/L-temp   # changed to suit the system layout.
while true
do
	# t1=`create a temporary file name`
	t1=`mktemp $TDIR/1111XXXX`
	t2=`mktemp $TDIR/2222XXXX`
	t3=`mktemp $TDIR/3333XXXX`

	# big-file is a 26+MiB file.
	./cp-test big-file ${t1}
	sleep 2
	./cp-test ${t1} ${t2}
	sleep 2
	./cp-test ${t2} ${t3}
	sleep 4
	rm -f ${t1} ${t2} ${t3}
	sleep 2
done

The other side: CIFS share is on Windows 7.
I tried the remedies discussed in
https://wiki.archlinux.org/index.php/Samba/Troubleshooting
and in a few other places
to remedy the error ("cannot allocate memory" due to non-paged resource
allocation failure on Win7, and subsequent mount failure on linux side.

Symptom: after a few tests of network failures simulated by
disabling and enabling network interface of the VMPlayer,
I noticed an incarnation of the program ./cp-test got stuck
in "D" state, and could not be interrupted (^C) at all.
I mounted CIFS-share with default option and so "soft" should be in effect.

Since this happened already after a few tests were performed,
I cannot exclude the possibility of screwed up Windows7 host, but even 
after a full day,
I still cannot run "ls -lR" without getting the it hung (I cannot 
interrupt it with
^C).

On the remote side, in Win7 system log, I see about the time the problem 
started
(24 hours ago or so) that windows was complaining that

The system could not allocate 983 work items in 60 seconds
The system could not allocate 983 work items in 60 seconds
  etc.
(my translation : I am using Japanese windows and so not sure what
the English windows would show.)

Now after 24 hours, I don't see it any more even when local "ls -lR" 
gets hung. I just tested.
So it now becomes pure local issue. The driver gets hung somewhere 
without accessing the
remote server at all. (Right, I see not much network traffic.)

Here is the dmesg output : I only copied the last part of the output
and threw away unrelated messages (unrelated, I hope).

[133221.834132] FS-Cache: Netfs 'cifs' registered for caching
[133221.834292] Key type cifs.spnego registered
[133221.834322] Key type cifs.idmap registered
[133221.966838] Status code returned 0xc000006d NT_STATUS_LOGON_FAILURE
[133221.966846] CIFS VFS: Send error in SessSetup = -13
[133221.967211] CIFS VFS: cifs_mount failed w/return code = -13
[133331.808616] CIFS VFS: Error -104 sending data on socket to server
[133331.808644] CIFS VFS: Error -32 sending data on socket to server

		[ lots of same messages (-32)...]

[133331.809348] CIFS VFS: Error -32 sending data on socket to server

		**** Here I simulated the network error again ****

[133566.580607] e1000: eth0 NIC Link is Down
[133566.580722] e1000 0000:02:01.0 eth0: Reset adapter
[133604.856771] e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow 
Control: None

                 **** Somehow CIFS in this version of linux seems to respond
		     only after 120 seconds timeout. I thought there was 15 seconds
		     timeout. ****

[133690.810481] CIFS VFS: Server 192.168.0.112 has not responded in 120 
seconds. Reconnecting...
[133929.781446] e1000: eth0 NIC Link is Down
[133929.781621] e1000 0000:02:01.0 eth0: Reset adapter
[133957.933636] e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow 
Control: None
[134054.949640] CIFS VFS: Server 192.168.0.112 has not responded in 120 
seconds. Reconnecting...

		**** Obviously a read/write routine gets stuck more than 120 seconds.
		     CIFS is being remounted after 120 seconds, but remount took more
		     than a few seconds, I guess. So 120+ seconds hung for the
		     stucked task/process ****

[134251.478654] INFO: task kworker/0:166:17092 blocked for more than 120 
seconds.
[134251.478659] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[134251.478661] kworker/0:166   D ffff88028b613f40     0 17092      2 
0x00000000
[134251.478694] Workqueue: cifsiod cifs_oplock_break [cifs]
[134251.478697]  ffff8800a3c54100 0000000000000046 ffffffff81613400 
0000000000013f40
[134251.478703]  ffff88005e8a1fd8 ffff88005e8a1fd8 ffff8800a3c54100 
ffff88028b613f40
[134251.478706]  ffff8800a3c54100 ffff88005e8a1d28 ffffffff810c051f 
0000000000000002
[134251.478709] Call Trace:
[134251.478781]  [<ffffffff810c051f>] ? __lock_page+0x61/0x61
[134251.478820]  [<ffffffff813858be>] ? io_schedule+0x54/0x69
[134251.478824]  [<ffffffff810c0524>] ? sleep_on_page+0x5/0x8
[134251.478827]  [<ffffffff813846dd>] ? __wait_on_bit+0x3b/0x6e
[134251.478829]  [<ffffffff810c05ce>] ? wait_on_page_bit+0x69/0x6e
[134251.478851]  [<ffffffff81057ca7>] ? autoremove_wake_function+0x2a/0x2a
[134251.478854]  [<ffffffff810c0c7b>] ? filemap_fdatawait_range+0x65/0xfa
[134251.478860]  [<ffffffffa04dec18>] ? cifs_oplock_break+0xd5/0x21d [cifs]
[134251.478865]  [<ffffffff8105f74a>] ? finish_task_switch+0x81/0xaa
[134251.478871]  [<ffffffff81052a71>] ? process_one_work+0x18b/0x28c
[134251.478873]  [<ffffffff81052f1b>] ? worker_thread+0x121/0x1e7
[134251.478876]  [<ffffffff81052dfa>] ? rescuer_thread+0x265/0x265
[134251.478878]  [<ffffffff81057325>] ? kthread+0x7d/0x85
[134251.478881]  [<ffffffff810572a8>] ? __kthread_parkme+0x59/0x59
[134251.478885]  [<ffffffff8138b47c>] ? ret_from_fork+0x7c/0xb0
[134251.478887]  [<ffffffff810572a8>] ? __kthread_parkme+0x59/0x59
[134251.478895] INFO: task pool:17993 blocked for more than 120 seconds.
[134251.478897] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[134251.478898] pool            D ffff88028b613f40     0 17993   5142 
0x00000000
[134251.478901]  ffff88027cbe6780 0000000000000082 ffffffff81613400 
0000000000013f40
[134251.478904]  ffff880221259fd8 ffff880221259fd8 ffff88027cbe6780 
ffff88028b613f40
[134251.478906]  ffff88027cbe6780 ffff880221259bc0 ffffffff810c051f 
0000000000000002
[134251.478909] Call Trace:
[134251.478911]  [<ffffffff810c051f>] ? __lock_page+0x61/0x61
[134251.478914]  [<ffffffff813858be>] ? io_schedule+0x54/0x69
[134251.478916]  [<ffffffff810c0524>] ? sleep_on_page+0x5/0x8
[134251.478918]  [<ffffffff813846dd>] ? __wait_on_bit+0x3b/0x6e
[134251.478920]  [<ffffffff810c05ce>] ? wait_on_page_bit+0x69/0x6e
[134251.478922]  [<ffffffff81057ca7>] ? autoremove_wake_function+0x2a/0x2a
[134251.478987]  [<ffffffff810cb14b>] ? 
invalidate_inode_pages2_range+0x94/0x226
[134251.478995]  [<ffffffffa04e64af>] ? 
cifs_invalidate_mapping+0x22/0x51 [cifs]
[134251.479000]  [<ffffffffa04dce7a>] ? cifs_d_revalidate+0x17/0x88 [cifs]
[134251.479022]  [<ffffffff81111ad0>] ? lookup_fast+0x17f/0x213
[134251.479026]  [<ffffffff81111d7b>] ? walk_component+0x33/0x1a2
[134251.479029]  [<ffffffff81112b39>] ? path_lookupat+0x8e/0x293
[134251.479034]  [<ffffffff810fa52e>] ? kmem_cache_alloc+0x8c/0xfd
[134251.479037]  [<ffffffff81112d5d>] ? filename_lookup+0x1f/0x73
[134251.479054]  [<ffffffff81114efe>] ? user_path_at_empty+0x6f/0xa6
[134251.479064]  [<ffffffff8107c8f5>] ? do_futex+0xd1/0x7b5
[134251.479066]  [<ffffffff8110d1f7>] ? vfs_fstatat+0x3e/0x8b
[134251.479069]  [<ffffffff8110d4bd>] ? SYSC_newlstat+0x10/0x29
[134251.479072]  [<ffffffff8138b529>] ? system_call_fastpath+0x16/0x1b
[134251.479074] INFO: task pool:18378 blocked for more than 120 seconds.
[134251.479076] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[134251.479077] pool            D ffff88028b633f40     0 18378   5142 
0x00000000
[134251.479079]  ffff88010cc2c840 0000000000000082 ffff880281179780 
0000000000013f40
[134251.479082]  ffff88024678bfd8 ffff88024678bfd8 ffff88010cc2c840 
ffff88028b633f40
[134251.479084]  ffff88010cc2c840 ffff88024678bbc0 0000000000000002 
ffffffff810c051f
[134251.479087] Call Trace:
[134251.479089]  [<ffffffff810c051f>] ? __lock_page+0x61/0x61
[134251.479092]  [<ffffffff813858be>] ? io_schedule+0x54/0x69
[134251.479094]  [<ffffffff810c0524>] ? sleep_on_page+0x5/0x8
[134251.479096]  [<ffffffff813847c0>] ? __wait_on_bit_lock+0x3a/0x7e
[134251.479098]  [<ffffffff810c051a>] ? __lock_page+0x5c/0x61
[134251.479101]  [<ffffffff81057ca7>] ? autoremove_wake_function+0x2a/0x2a
[134251.479105]  [<ffffffff810cb121>] ? 
invalidate_inode_pages2_range+0x6a/0x226
[134251.479111]  [<ffffffffa04e64af>] ? 
cifs_invalidate_mapping+0x22/0x51 [cifs]
[134251.479116]  [<ffffffffa04dce7a>] ? cifs_d_revalidate+0x17/0x88 [cifs]
[134251.479119]  [<ffffffff81111ad0>] ? lookup_fast+0x17f/0x213
[134251.479122]  [<ffffffff81111d7b>] ? walk_component+0x33/0x1a2
[134251.479125]  [<ffffffff81112b39>] ? path_lookupat+0x8e/0x293
[134251.479128]  [<ffffffff810fa52e>] ? kmem_cache_alloc+0x8c/0xfd
[134251.479131]  [<ffffffff81112d5d>] ? filename_lookup+0x1f/0x73
[134251.479133]  [<ffffffff81114efe>] ? user_path_at_empty+0x6f/0xa6
[134251.479136]  [<ffffffff810f9498>] ? ____cache_alloc+0x1d3/0x290
[134251.479138]  [<ffffffff8110d1f7>] ? vfs_fstatat+0x3e/0x8b
[134251.479141]  [<ffffffff8109fb12>] ? __call_rcu.constprop.51+0xc2/0x1c6
[134251.479143]  [<ffffffff8110d4bd>] ? SYSC_newlstat+0x10/0x29
[134251.479147]  [<ffffffff8104f3f1>] ? SyS_prctl+0x104/0x32f
[134251.479149]  [<ffffffff8138b529>] ? system_call_fastpath+0x16/0x1b
[134251.479151] INFO: task pool:18384 blocked for more than 120 seconds.
[134251.479153] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[134251.479154] pool            D ffff88028b613f40     0 18384   5142 
0x00000000
[134251.479156]  ffff88027c9c8800 0000000000000082 ffffffff81613400 
0000000000013f40
[134251.479159]  ffff88024267dfd8 ffff88024267dfd8 ffff88027c9c8800 
ffff88028b613f40
[134251.479161]  ffff88027c9c8800 ffff88024267dbc0 0000000000000002 
ffffffff810c051f
[134251.479163] Call Trace:
[134251.479166]  [<ffffffff810c051f>] ? __lock_page+0x61/0x61
[134251.479168]  [<ffffffff813858be>] ? io_schedule+0x54/0x69
[134251.479170]  [<ffffffff810c0524>] ? sleep_on_page+0x5/0x8
[134251.479172]  [<ffffffff813847c0>] ? __wait_on_bit_lock+0x3a/0x7e
[134251.479174]  [<ffffffff810c051a>] ? __lock_page+0x5c/0x61
[134251.479177]  [<ffffffff81057ca7>] ? autoremove_wake_function+0x2a/0x2a
[134251.479179]  [<ffffffff810cb121>] ? 
invalidate_inode_pages2_range+0x6a/0x226
[134251.479184]  [<ffffffffa04e64af>] ? 
cifs_invalidate_mapping+0x22/0x51 [cifs]
[134251.479189]  [<ffffffffa04dce7a>] ? cifs_d_revalidate+0x17/0x88 [cifs]
[134251.479192]  [<ffffffff81111ad0>] ? lookup_fast+0x17f/0x213
[134251.479195]  [<ffffffff81111d7b>] ? walk_component+0x33/0x1a2
[134251.479197]  [<ffffffff81112b39>] ? path_lookupat+0x8e/0x293
[134251.479200]  [<ffffffff810fa52e>] ? kmem_cache_alloc+0x8c/0xfd
[134251.479203]  [<ffffffff81112d5d>] ? filename_lookup+0x1f/0x73
[134251.479205]  [<ffffffff81114efe>] ? user_path_at_empty+0x6f/0xa6
[134251.479208]  [<ffffffff8105f5ff>] ? __wake_up_sync_key+0x3d/0x55
[134251.479211]  [<ffffffff810fa52e>] ? kmem_cache_alloc+0x8c/0xfd
[134251.479213]  [<ffffffff8110d1f7>] ? vfs_fstatat+0x3e/0x8b
[134251.479215]  [<ffffffff8109fb12>] ? __call_rcu.constprop.51+0xc2/0x1c6
[134251.479217]  [<ffffffff8110d4bd>] ? SYSC_newlstat+0x10/0x29
[134251.479220]  [<ffffffff8104f3f1>] ? SyS_prctl+0x104/0x32f
[134251.479223]  [<ffffffff8138b529>] ? system_call_fastpath+0x16/0x1b
[134251.479225] INFO: task pool:18385 blocked for more than 120 seconds.
[134251.479226] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[134251.479227] pool            D ffff88028b613f40     0 18385   5142 
0x00000000
[134251.479229]  ffff8802427e9080 0000000000000082 ffffffff81613400 
0000000000013f40
[134251.479232]  ffff88024674ffd8 ffff88024674ffd8 ffff8802427e9080 
ffff88028b613f40
[134251.479234]  ffff8802427e9080 ffff88024674fda8 ffffffff810c051f 
0000000000000002
[134251.479236] Call Trace:
[134251.479239]  [<ffffffff810c051f>] ? __lock_page+0x61/0x61
[134251.479241]  [<ffffffff813858be>] ? io_schedule+0x54/0x69
[134251.479243]  [<ffffffff810c0524>] ? sleep_on_page+0x5/0x8
[134251.479245]  [<ffffffff813846dd>] ? __wait_on_bit+0x3b/0x6e
[134251.479247]  [<ffffffff810c05ce>] ? wait_on_page_bit+0x69/0x6e
[134251.479250]  [<ffffffff81057ca7>] ? autoremove_wake_function+0x2a/0x2a
[134251.479252]  [<ffffffff810c0c7b>] ? filemap_fdatawait_range+0x65/0xfa
[134251.479259]  [<ffffffffa04e6706>] ? cifs_getattr+0x45/0xe6 [cifs]
[134251.479262]  [<ffffffff8110d208>] ? vfs_fstatat+0x4f/0x8b
[134251.479264]  [<ffffffff8110d4bd>] ? SYSC_newlstat+0x10/0x29
[134251.479267]  [<ffffffff8104f3f1>] ? SyS_prctl+0x104/0x32f
[134251.479270]  [<ffffffff8138b529>] ? system_call_fastpath+0x16/0x1b
[134251.479273] INFO: task cp-test:17969 blocked for more than 120 seconds.
[134251.479275] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[134251.479276] cp-test         D ffff88028b613f40     0 17969  16775 
0x00000000
[134251.479278]  ffff880221270040 0000000000000086 ffffffff81613400 
0000000000013f40
[134251.479281]  ffff88010cc85fd8 ffff88010cc85fd8 ffff880221270040 
ffff88028b613f40
[134251.479283]  ffff880221270040 ffff88010cc85e38 ffffffff810c051f 
0000000000000002
[134251.479285] Call Trace:
[134251.479288]  [<ffffffff810c051f>] ? __lock_page+0x61/0x61
[134251.479290]  [<ffffffff813858be>] ? io_schedule+0x54/0x69
[134251.479292]  [<ffffffff810c0524>] ? sleep_on_page+0x5/0x8
[134251.479294]  [<ffffffff813846dd>] ? __wait_on_bit+0x3b/0x6e
[134251.479296]  [<ffffffff810c05ce>] ? wait_on_page_bit+0x69/0x6e
[134251.479299]  [<ffffffff81057ca7>] ? autoremove_wake_function+0x2a/0x2a
[134251.479301]  [<ffffffff810c0c7b>] ? filemap_fdatawait_range+0x65/0xfa
[134251.479304]  [<ffffffff810c22be>] ? filemap_write_and_wait+0x20/0x33
[134251.479309]  [<ffffffffa04e2d79>] ? cifs_flush+0x1d/0x4d [cifs]
[134251.479329]  [<ffffffff81107bc5>] ? filp_close+0x37/0x68
[134251.479333]  [<ffffffff81108c82>] ? SyS_close+0x1a/0x3c
[134251.479335]  [<ffffffff8138b529>] ? system_call_fastpath+0x16/0x1b
[134371.629437] INFO: task kworker/0:166:17092 blocked for more than 120 
seconds.
[134371.629442] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[134371.629445] kworker/0:166   D ffff88028b613f40     0 17092      2 
0x00000000
[134371.629504] Workqueue: cifsiod cifs_oplock_break [cifs]
[134371.629507]  ffff8800a3c54100 0000000000000046 ffffffff81613400 
0000000000013f40
[134371.629511]  ffff88005e8a1fd8 ffff88005e8a1fd8 ffff8800a3c54100 
ffff88028b613f40
[134371.629515]  ffff8800a3c54100 ffff88005e8a1d28 ffffffff810c051f 
0000000000000002
[134371.629518] Call Trace:
[134371.629526]  [<ffffffff810c051f>] ? __lock_page+0x61/0x61
[134371.629532]  [<ffffffff813858be>] ? io_schedule+0x54/0x69
[134371.629535]  [<ffffffff810c0524>] ? sleep_on_page+0x5/0x8
[134371.629538]  [<ffffffff813846dd>] ? __wait_on_bit+0x3b/0x6e
[134371.629541]  [<ffffffff810c05ce>] ? wait_on_page_bit+0x69/0x6e
[134371.629546]  [<ffffffff81057ca7>] ? autoremove_wake_function+0x2a/0x2a
[134371.629549]  [<ffffffff810c0c7b>] ? filemap_fdatawait_range+0x65/0xfa
[134371.629557]  [<ffffffffa04dec18>] ? cifs_oplock_break+0xd5/0x21d [cifs]
[134371.629562]  [<ffffffff8105f74a>] ? finish_task_switch+0x81/0xaa
[134371.629566]  [<ffffffff81052a71>] ? process_one_work+0x18b/0x28c
[134371.629570]  [<ffffffff81052f1b>] ? worker_thread+0x121/0x1e7
[134371.629573]  [<ffffffff81052dfa>] ? rescuer_thread+0x265/0x265
[134371.629576]  [<ffffffff81057325>] ? kthread+0x7d/0x85
[134371.629579]  [<ffffffff810572a8>] ? __kthread_parkme+0x59/0x59
[134371.629583]  [<ffffffff8138b47c>] ? ret_from_fork+0x7c/0xb0
[134371.629586]  [<ffffffff810572a8>] ? __kthread_parkme+0x59/0x59
[134371.629596] INFO: task pool:17993 blocked for more than 120 seconds.
[134371.629598] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[134371.629600] pool            D ffff88028b613f40     0 17993   5142 
0x00000000
[134371.629603]  ffff88027cbe6780 0000000000000082 ffffffff81613400 
0000000000013f40
[134371.629606]  ffff880221259fd8 ffff880221259fd8 ffff88027cbe6780 
ffff88028b613f40
[134371.629609]  ffff88027cbe6780 ffff880221259bc0 ffffffff810c051f 
0000000000000002
[134371.629613] Call Trace:
[134371.629616]  [<ffffffff810c051f>] ? __lock_page+0x61/0x61
[134371.629619]  [<ffffffff813858be>] ? io_schedule+0x54/0x69
[134371.629622]  [<ffffffff810c0524>] ? sleep_on_page+0x5/0x8
[134371.629625]  [<ffffffff813846dd>] ? __wait_on_bit+0x3b/0x6e
[134371.629632]  [<ffffffff810c05ce>] ? wait_on_page_bit+0x69/0x6e
[134371.629636]  [<ffffffff81057ca7>] ? autoremove_wake_function+0x2a/0x2a
[134371.629641]  [<ffffffff810cb14b>] ? 
invalidate_inode_pages2_range+0x94/0x226
[134371.629649]  [<ffffffffa04e64af>] ? 
cifs_invalidate_mapping+0x22/0x51 [cifs]
[134371.629656]  [<ffffffffa04dce7a>] ? cifs_d_revalidate+0x17/0x88 [cifs]
[134371.629661]  [<ffffffff81111ad0>] ? lookup_fast+0x17f/0x213
[134371.629664]  [<ffffffff81111d7b>] ? walk_component+0x33/0x1a2
[134371.629668]  [<ffffffff81112b39>] ? path_lookupat+0x8e/0x293
[134371.629673]  [<ffffffff810fa52e>] ? kmem_cache_alloc+0x8c/0xfd
[134371.629677]  [<ffffffff81112d5d>] ? filename_lookup+0x1f/0x73
[134371.629680]  [<ffffffff81114efe>] ? user_path_at_empty+0x6f/0xa6
[134371.629686]  [<ffffffff8107c8f5>] ? do_futex+0xd1/0x7b5
[134371.629689]  [<ffffffff8110d1f7>] ? vfs_fstatat+0x3e/0x8b
[134371.629692]  [<ffffffff8110d4bd>] ? SYSC_newlstat+0x10/0x29
[134371.629696]  [<ffffffff8138b529>] ? system_call_fastpath+0x16/0x1b
[134371.629699] INFO: task pool:18378 blocked for more than 120 seconds.
[134371.629700] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[134371.629702] pool            D ffff88028b633f40     0 18378   5142 
0x00000000
[134371.629705]  ffff88010cc2c840 0000000000000082 ffff880281179780 
0000000000013f40
[134371.629708]  ffff88024678bfd8 ffff88024678bfd8 ffff88010cc2c840 
ffff88028b633f40
[134371.629711]  ffff88010cc2c840 ffff88024678bbc0 0000000000000002 
ffffffff810c051f
[134371.629715] Call Trace:
[134371.629717]  [<ffffffff810c051f>] ? __lock_page+0x61/0x61
[134371.629721]  [<ffffffff813858be>] ? io_schedule+0x54/0x69
[134371.629723]  [<ffffffff810c0524>] ? sleep_on_page+0x5/0x8
[134371.629727]  [<ffffffff813847c0>] ? __wait_on_bit_lock+0x3a/0x7e
[134371.629729]  [<ffffffff810c051a>] ? __lock_page+0x5c/0x61
[134371.629732]  [<ffffffff81057ca7>] ? autoremove_wake_function+0x2a/0x2a
[134371.629736]  [<ffffffff810cb121>] ? 
invalidate_inode_pages2_range+0x6a/0x226
[134371.629743]  [<ffffffffa04e64af>] ? 
cifs_invalidate_mapping+0x22/0x51 [cifs]
[134371.629749]  [<ffffffffa04dce7a>] ? cifs_d_revalidate+0x17/0x88 [cifs]
[134371.629753]  [<ffffffff81111ad0>] ? lookup_fast+0x17f/0x213
[134371.629757]  [<ffffffff81111d7b>] ? walk_component+0x33/0x1a2
[134371.629760]  [<ffffffff81112b39>] ? path_lookupat+0x8e/0x293
[134371.629764]  [<ffffffff810fa52e>] ? kmem_cache_alloc+0x8c/0xfd
[134371.629768]  [<ffffffff81112d5d>] ? filename_lookup+0x1f/0x73
[134371.629770]  [<ffffffff81114efe>] ? user_path_at_empty+0x6f/0xa6
[134371.629775]  [<ffffffff810f9498>] ? ____cache_alloc+0x1d3/0x290
[134371.629777]  [<ffffffff8110d1f7>] ? vfs_fstatat+0x3e/0x8b
[134371.629781]  [<ffffffff8109fb12>] ? __call_rcu.constprop.51+0xc2/0x1c6
[134371.629784]  [<ffffffff8110d4bd>] ? SYSC_newlstat+0x10/0x29
[134371.629788]  [<ffffffff8104f3f1>] ? SyS_prctl+0x104/0x32f
[134371.629792]  [<ffffffff8138b529>] ? system_call_fastpath+0x16/0x1b
[134371.629794] INFO: task pool:18384 blocked for more than 120 seconds.
[134371.629796] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[134371.629798] pool            D ffff88028b613f40     0 18384   5142 
0x00000000
[134371.629801]  ffff88027c9c8800 0000000000000082 ffffffff81613400 
0000000000013f40
[134371.629804]  ffff88024267dfd8 ffff88024267dfd8 ffff88027c9c8800 
ffff88028b613f40
[134371.629807]  ffff88027c9c8800 ffff88024267dbc0 0000000000000002 
ffffffff810c051f
[134371.629811] Call Trace:
[134371.629813]  [<ffffffff810c051f>] ? __lock_page+0x61/0x61
[134371.629817]  [<ffffffff813858be>] ? io_schedule+0x54/0x69
[134371.629819]  [<ffffffff810c0524>] ? sleep_on_page+0x5/0x8
[134371.629822]  [<ffffffff813847c0>] ? __wait_on_bit_lock+0x3a/0x7e
[134371.629825]  [<ffffffff810c051a>] ? __lock_page+0x5c/0x61
[134371.629828]  [<ffffffff81057ca7>] ? autoremove_wake_function+0x2a/0x2a
[134371.629831]  [<ffffffff810cb121>] ? 
invalidate_inode_pages2_range+0x6a/0x226
[134371.629838]  [<ffffffffa04e64af>] ? 
cifs_invalidate_mapping+0x22/0x51 [cifs]
[134371.629846]  [<ffffffffa04dce7a>] ? cifs_d_revalidate+0x17/0x88 [cifs]
[134371.629850]  [<ffffffff81111ad0>] ? lookup_fast+0x17f/0x213
[134371.629854]  [<ffffffff81111d7b>] ? walk_component+0x33/0x1a2
[134371.629857]  [<ffffffff81112b39>] ? path_lookupat+0x8e/0x293
[134371.629861]  [<ffffffff810fa52e>] ? kmem_cache_alloc+0x8c/0xfd
[134371.629865]  [<ffffffff81112d5d>] ? filename_lookup+0x1f/0x73
[134371.629868]  [<ffffffff81114efe>] ? user_path_at_empty+0x6f/0xa6
[134371.629871]  [<ffffffff8105f5ff>] ? __wake_up_sync_key+0x3d/0x55
[134371.629875]  [<ffffffff810fa52e>] ? kmem_cache_alloc+0x8c/0xfd
[134371.629878]  [<ffffffff8110d1f7>] ? vfs_fstatat+0x3e/0x8b
[134371.629881]  [<ffffffff8109fb12>] ? __call_rcu.constprop.51+0xc2/0x1c6
[134371.629884]  [<ffffffff8110d4bd>] ? SYSC_newlstat+0x10/0x29
[134371.629888]  [<ffffffff8104f3f1>] ? SyS_prctl+0x104/0x32f
[134371.629891]  [<ffffffff8138b529>] ? system_call_fastpath+0x16/0x1b
[184501.155185] CIFS VFS: Server 192.168.0.112 has not responded in 120 
seconds. Reconnecting...

		**** But now after this, the test program copying a file from the other
		     gets stuck in D state and cannot be killed.
		     I think only reboot will remedy this situation.

Hope this helps.

Even if this could be triggered by flakey windows 7 CIFS-share issues,
I think it is worthwhile to make CIFS driver robust in such situations.

I am keeping this linux running in this manner and so
let me know if you need some runtime information which can be gleaned by
some means (like system trace, etc.). Please advise how to obtain the 
information in that case (the particular command to obtain the desired 
value will be useful.)

TIA