Bug 86661 - BUG: unable to handle kernel NULL pointer dereference; IP: [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
Summary: BUG: unable to handle kernel NULL pointer dereference; IP: [<ffffffff812280c2...
Status: ASSIGNED
Alias: None
Product: File System
Classification: Unclassified
Component: NFS (show other bugs)
Hardware: x86-64 Linux
: P1 high
Assignee: Trond Myklebust
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2014-10-21 15:37 UTC by Dwayne Hart
Modified: 2016-04-04 20:19 UTC (History)
3 users (show)

See Also:
Kernel Version: 3.17.1
Subsystem:
Regression: No
Bisected commit-id:

Attachments
Excerpt from dmesg.log (36.03 KB, application/octet-stream)
2014-10-21 15:37 UTC, Dwayne Hart 		Details
Add an attachment (proposed patch, testcase, etc.)

Description Dwayne Hart 2014-10-21 15:37:17 UTC 
Created attachment 154421 [details]
Excerpt from dmesg.log

A user tries to log into one of our systems and encounters stale NFS when trying to access content in their account. Or the user has been using the system for a period of time and all of a sudden they are unable to access the content in their home directory.
Comment 1 Trond Myklebust 2014-10-21 16:22:51 UTC 
Added Neil to the Cc list since this looks like an interaction between the new RCU code and automounts.
Comment 2 Neil Brown 2014-10-21 22:58:33 UTC 
I don't *think* it is RCU related, as d_automount is never called in RCU-WALK mode.

It appears that ->d_automount() is being called on a path with a negative dentry.
That means the dentry has DCACHE_NEED_AUTOMOUNT set.  Within NFS, that only gets set if the dentry has an inode that IS_AUTOMOUNT().
Seeing there is no inode, it cannot possibly be IS_AUTOMOUNT().

My best guess is that the dentry *did* have an IS_AUTOMOUNT() inode, but this was removed by dentry_unlink_inode() or similar, thus leaving a dentry with DCACHE_NEED_AUTOMOUNT set, but with no inode.
I don't know if this is really possible.

Is problem repeatable?
Comment 3 Trond Myklebust 2014-10-22 09:47:22 UTC 
(In reply to Neil Brown from comment #2)
> I don't *think* it is RCU related, as d_automount is never called in
> RCU-WALK mode.

Ah, you are right Neil. Sorry.
Comment 4 Trond Myklebust 2014-10-22 09:52:31 UTC 
Dwayne, what server are you using, and which filesystem is it exporting? Could you please list the contents of /etc/exports on the server?

On the client, would it be possible to list the contents of /proc/mounts while one of the users that has been seeing problems is logged in?
Comment 5 Dwayne Hart 2014-10-22 11:30:06 UTC 
The system that the end user is making use of is a Gentoo 64bit implementation. The file server is also running the same version of OS (using the 3.8.13 kernel). The person is either using PuTTy or a Linux ssh client when connecting to the point of entry system. 

The file server has the following in its /etc/exports file:

/nfs4                                   *.<partial domain name>(ro,fsid=0,no_subtree_check)
/nfs4/users/<path 1>                  *.<partial domain name>(rw,no_subtree_check)
/nfs4/users/<path 2>                  *.<partial domain name>(rw,no_subtree_check)

The point of entry Linux system has the following in its /etc/autofs/auto_maps/direct file:

/users/<path 2>    -rw,fstype=nfs4,noatime,noacl,nodiratime,hard,intr    <file server>:/users/<path 2>

Currently, the /proc/mounts contains the following substrings from a working point in time:

/etc/autofs/auto_maps/direct /users/<path 2> autofs rw,relatime,fd=19,pgrp=2627,timeout=3600,minproto=5,maxproto=5,direct 0 0
<file server>:/users/<path 2> /users/<path 2> nfs4 rw,noatime,nodiratime,vers=4.0,rsize=131072,wsize=131072,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=192.168.204.93,local_lock=none,addr=192.168.180.17 0 0
Comment 6 Trond Myklebust 2014-10-22 11:54:54 UTC 
Are /nfs4, /nfs4/users/<path 1>, and /nfs4/users/<path 2> all located on different filesystems? If not, then you need to use subtree checking, and failing to do so might explain the ESTALE issues.
Comment 7 Dwayne Hart 2014-10-22 12:21:57 UTC 
/nfs4, /nfs4/users/math/misc/fs1, /nfs4/users/users/math/misc/fs2, etc. Are the same directory structure. 

/nfs4/users/math/misc/fs1 is a bind mount from /users/math/misc/fs1 which contains a set of users home directories and /nfs4/users/math/misc/fs2 is a bind mount from /users/users/math/misc/fs2 which contains a different set of users home directories. 

/users/math/misc/fs1 and fs2 are backed by a separate iSCSI disks.
Comment 8 Trond Myklebust 2014-10-23 15:22:40 UTC 
Hi Dwayne,

Can you try backing out commit f39c01047994e66e7f3d89ddb4c6141f23349d8d (NFS: remove BUG possibility in nfs4_open_and_get_state) and then backing out commit 4fa2c54b5198d09607a534e2fd436581064587ed (NFS: nfs4_do_open should add negative results to the dcache) and then recompiling?

The call to d_delete() in those is not covered by the usual checks, and can be called from some very odd contexts (such as finish_open()). In addition, it looks to me as if the root cause of the performance problem those patches are trying to fix is the simply the lack of a call to nfs_set_verifier() in the ENOENT path in nfs_atomic_open().
Comment 9 Dwayne Hart 2014-10-23 21:41:33 UTC 
Hi Trond,

I've compiled a new version of 3.17.1 with the modifications to the kernel source you requested. I've rebooted one of my systems to try it out and will deploy it to another system later tomorrow which was having the same issue.
Comment 10 Dwayne Hart 2014-10-24 16:53:43 UTC 
I have the server which initially showed this error using the newly built kernel. If I hear anything over the weekend I'll update this ticket.
Comment 11 Dwayne Hart 2014-11-16 14:01:09 UTC 
Hi,

One of our research file servers had the following issue on Friday, October 31st. Its currently running the modified 3.17.1 kernel.

[Fri Oct 31 19:15:13 2014] WARNING: CPU: 1 PID: 6784 at fs/dcache.c:1318 umount_check+0x77/0x7b()
[Fri Oct 31 19:15:13 2014] Modules linked in:
[Fri Oct 31 19:15:13 2014] CPU: 1 PID: 6784 Comm: umount.nfs4 Not tainted 3.17.1-gentoo20141023m-00002-gbe4fcc3 #2
[Fri Oct 31 19:15:13 2014] Hardware name: System manufacturer System Product Name/P6X58-E PRO, BIOS 0504    07/28/2011
[Fri Oct 31 19:15:13 2014]  0000000000000526 ffff88031c70fcc8 ffffffff81800a85 0000000000000000
[Fri Oct 31 19:15:13 2014]  0000000000000000 ffff88031c70fd08 ffffffff8103c4f3 ffff88031c70fd30
[Fri Oct 31 19:15:13 2014]  ffffffff81125a28 ffff880316e7d010 0000000000015c80 ffff880326786901
[Fri Oct 31 19:15:13 2014] Call Trace:
[Fri Oct 31 19:15:13 2014]  [<ffffffff81800a85>] dump_stack+0x46/0x58
[Fri Oct 31 19:15:13 2014]  [<ffffffff8103c4f3>] warn_slowpath_common+0x7c/0x96
[Fri Oct 31 19:15:13 2014]  [<ffffffff81125a28>] ? umount_check+0x77/0x7b
[Fri Oct 31 19:15:13 2014]  [<ffffffff8103c522>] warn_slowpath_null+0x15/0x17
[Fri Oct 31 19:15:13 2014]  [<ffffffff81125a28>] umount_check+0x77/0x7b
[Fri Oct 31 19:15:13 2014]  [<ffffffff811248c6>] d_walk+0x115/0x2d4
[Fri Oct 31 19:15:13 2014]  [<ffffffff81126484>] ? do_one_tree+0x22/0x36
[Fri Oct 31 19:15:13 2014]  [<ffffffff811259b1>] ? d_instantiate_unique+0x68/0x68
[Fri Oct 31 19:15:13 2014]  [<ffffffff81126484>] do_one_tree+0x22/0x36
[Fri Oct 31 19:15:13 2014]  [<ffffffff8112697d>] shrink_dcache_for_umount+0x59/0x6b
[Fri Oct 31 19:15:13 2014]  [<ffffffff8111537e>] generic_shutdown_super+0x1e/0xed
[Fri Oct 31 19:15:13 2014]  [<ffffffff811154c0>] kill_anon_super+0xe/0x19
[Fri Oct 31 19:15:13 2014]  [<ffffffff8121e439>] nfs_kill_super+0x12/0x1e
[Fri Oct 31 19:15:13 2014]  [<ffffffff81115a02>] deactivate_locked_super+0x36/0x4b
[Fri Oct 31 19:15:13 2014]  [<ffffffff811160f1>] deactivate_super+0x3a/0x3e
[Fri Oct 31 19:15:13 2014]  [<ffffffff8112d0d4>] mntput_no_expire+0x1b0/0x1d2
[Fri Oct 31 19:15:13 2014]  [<ffffffff8112e4b3>] ? SyS_umount+0x395/0x3aa
[Fri Oct 31 19:15:13 2014]  [<ffffffff8112e4b3>] SyS_umount+0x395/0x3aa
[Fri Oct 31 19:15:13 2014]  [<ffffffff81808412>] ? system_call_fastpath+0x16/0x1b
[Fri Oct 31 19:15:13 2014]  [<ffffffff810f072a>] ? vm_munmap+0x4e/0x5e
[Fri Oct 31 19:15:13 2014]  [<ffffffff8112cf24>] ? mnt_get_count+0x53/0x53
[Fri Oct 31 19:15:13 2014]  [<ffffffff81808412>] system_call_fastpath+0x16/0x1b
[Fri Oct 31 19:15:13 2014] ---[ end trace f8d9e04a1786ebb6 ]---
Comment 12 Trond Myklebust 2014-11-16 16:53:06 UTC 
That doesn't look as if it is necessarily related to the original bug report. Could you please file it as a separate bugzilla?
Also, I would expect there to be a message of the form "BUG: Dentry XXXXXX {i=yyy, n=foo} still in use" that is intended to give you an idea of which file was still in use when the umount failed.
Comment 13 Dwayne Hart 2014-11-16 17:20:08 UTC 
Hi Tond,

I've opened the following BUG 88321.

Best,
Dwayne
Comment 14 Dwayne Hart 2014-11-16 22:54:55 UTC 
Hi Tron,

I came across the following information on one of our systems this morning. Its running the modified 3.17.1 kernel.

[Sun Nov 16 11:48:06 2014] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[Sun Nov 16 11:48:06 2014] IP: [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:48:06 2014] PGD 6dab2067 PUD 789b3067 PMD 0
[Sun Nov 16 11:48:06 2014] Oops: 0000 [#1] SMP
[Sun Nov 16 11:48:06 2014] Modules linked in:
[Sun Nov 16 11:48:06 2014] CPU: 0 PID: 15549 Comm: sftp-server Not tainted 3.17.1-gentoo20141023m-00002-gbe4fcc3 #2
[Sun Nov 16 11:48:06 2014] Hardware name: System manufacturer P5Q Premium, BIOS 1306 11/28/2013
[Sun Nov 16 11:48:06 2014] task: ffff880074ff2990 ti: ffff880042b30000 task.ti: ffff880042b30000
[Sun Nov 16 11:48:06 2014] RIP: 0010:[<ffffffff812280c2>]  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:48:06 2014] RSP: 0018:ffff880042b33bd8  EFLAGS: 00010246
[Sun Nov 16 11:48:06 2014] RAX: 0000000000000000 RBX: ffff880042b33d08 RCX: 0000000000000001
[Sun Nov 16 11:48:06 2014] RDX: ffffffff81848d00 RSI: 0000000000000000 RDI: ffff880042b33d08
[Sun Nov 16 11:48:06 2014] RBP: ffff880042b33bf8 R08: 0000000000000000 R09: ffffffff813bb847
[Sun Nov 16 11:48:06 2014] R10: ffffffff813bb847 R11: 0000000000000246 R12: 0000000000020000
[Sun Nov 16 11:48:06 2014] R13: 0000000000000000 R14: ffff880042b33d08 R15: ffff880074a63420
[Sun Nov 16 11:48:06 2014] FS:  00007fea10f11700(0000) GS:ffff88007b400000(0000) knlGS:0000000000000000
[Sun Nov 16 11:48:06 2014] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Sun Nov 16 11:48:06 2014] CR2: 0000000000000028 CR3: 00000000317a0000 CR4: 00000000000006f0
[Sun Nov 16 11:48:06 2014] Stack:
[Sun Nov 16 11:48:06 2014]  ffff880042b33d08 0000000000020000 0000000000000000 ffff880074ff2990
[Sun Nov 16 11:48:06 2014]  ffff880042b33c58 ffffffff8111b9f6 ffff880042b33d08 0000000000000001
[Sun Nov 16 11:48:06 2014]  ffff880042b33c58 0000000200000000 ffff880042b33c38 ffff880042b33dc0
[Sun Nov 16 11:48:06 2014] Call Trace:
[Sun Nov 16 11:48:06 2014]  [<ffffffff8111b9f6>] follow_managed+0x139/0x218
[Sun Nov 16 11:48:06 2014]  [<ffffffff8111c335>] lookup_fast+0x271/0x2c3
[Sun Nov 16 11:48:06 2014]  [<ffffffff8111d94d>] path_lookupat+0xdb/0x617
[Sun Nov 16 11:48:06 2014]  [<ffffffff81128f08>] ? touch_atime+0x116/0x123
[Sun Nov 16 11:48:06 2014]  [<ffffffff8111deaa>] filename_lookup.isra.46+0x21/0x59
[Sun Nov 16 11:48:06 2014]  [<ffffffff81120501>] user_path_at_empty+0x4e/0x8d
[Sun Nov 16 11:48:06 2014]  [<ffffffff8111a3ac>] ? pipe_read+0x262/0x274
[Sun Nov 16 11:48:06 2014]  [<ffffffff81112f11>] ? new_sync_read+0x72/0x99
[Sun Nov 16 11:48:06 2014]  [<ffffffff8112054c>] user_path_at+0xc/0xe
[Sun Nov 16 11:48:06 2014]  [<ffffffff81117587>] vfs_fstatat+0x49/0x8d
[Sun Nov 16 11:48:06 2014]  [<ffffffff811175e4>] vfs_lstat+0x19/0x1b
[Sun Nov 16 11:48:06 2014]  [<ffffffff81117718>] SyS_newlstat+0x15/0x2e
[Sun Nov 16 11:48:06 2014]  [<ffffffff813bb589>] ? lockdep_sys_exit_thunk+0x35/0x67
[Sun Nov 16 11:48:06 2014]  [<ffffffff81808412>] system_call_fastpath+0x16/0x1b
[Sun Nov 16 11:48:06 2014] Code: 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 55 f6 05 2b 98 91 01 01 48 89 e5 41 56 49 89 fe 41 55 41 54 53 48 8b 47 08 48 8b 40 68 <48> 8b 40 28 48 8b 98 20 06 00 00 74 0e 48 c7 c7 46 8a b2 81 31
[Sun Nov 16 11:48:06 2014] RIP  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:48:06 2014]  RSP <ffff880042b33bd8>
[Sun Nov 16 11:48:06 2014] CR2: 0000000000000028
[Sun Nov 16 11:48:06 2014] ---[ end trace 177aaf47fd4980d2 ]---
[Sun Nov 16 11:48:34 2014] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[Sun Nov 16 11:48:34 2014] IP: [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:48:34 2014] PGD 3db2a067 PUD 6db37067 PMD 0
[Sun Nov 16 11:48:34 2014] Oops: 0000 [#2] SMP
[Sun Nov 16 11:48:34 2014] Modules linked in:
[Sun Nov 16 11:48:34 2014] CPU: 1 PID: 13243 Comm: sftp-server Tainted: G      D        3.17.1-gentoo20141023m-00002-gbe4fcc3 #2
[Sun Nov 16 11:48:34 2014] Hardware name: System manufacturer P5Q Premium, BIOS 1306 11/28/2013
[Sun Nov 16 11:48:34 2014] task: ffff88001b9a07d0 ti: ffff88004cac0000 task.ti: ffff88004cac0000
[Sun Nov 16 11:48:34 2014] RIP: 0010:[<ffffffff812280c2>]  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:48:34 2014] RSP: 0018:ffff88004cac3bd8  EFLAGS: 00010246
[Sun Nov 16 11:48:34 2014] RAX: 0000000000000000 RBX: ffff88004cac3d08 RCX: 0000000000000001
[Sun Nov 16 11:48:34 2014] RDX: ffffffff81848d00 RSI: 0000000000000000 RDI: ffff88004cac3d08
[Sun Nov 16 11:48:34 2014] RBP: ffff88004cac3bf8 R08: 0000000000000000 R09: ffffffff813bb847
[Sun Nov 16 11:48:34 2014] R10: ffffffff813bb847 R11: 000000ff00000101 R12: 0000000000020000
[Sun Nov 16 11:48:34 2014] R13: 0000000000000000 R14: ffff88004cac3d08 R15: ffff880074a63420
[Sun Nov 16 11:48:34 2014] FS:  00007f15d128c700(0000) GS:ffff88007b600000(0000) knlGS:0000000000000000
[Sun Nov 16 11:48:34 2014] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Sun Nov 16 11:48:34 2014] CR2: 0000000000000028 CR3: 000000000977b000 CR4: 00000000000006e0
[Sun Nov 16 11:48:34 2014] Stack:
[Sun Nov 16 11:48:34 2014]  ffff88004cac3d08 0000000000020000 0000000000000000 ffff88001b9a07d0
[Sun Nov 16 11:48:34 2014]  ffff88004cac3c58 ffffffff8111b9f6 ffff88004cac3d08 0000000000000001
[Sun Nov 16 11:48:34 2014]  ffff88004cac3c58 0000000200000000 ffff88004cac3c38 ffff88004cac3dc0
[Sun Nov 16 11:48:34 2014] Call Trace:
[Sun Nov 16 11:48:34 2014]  [<ffffffff8111b9f6>] follow_managed+0x139/0x218
[Sun Nov 16 11:48:34 2014]  [<ffffffff8111c335>] lookup_fast+0x271/0x2c3
[Sun Nov 16 11:48:34 2014]  [<ffffffff8111d94d>] path_lookupat+0xdb/0x617
[Sun Nov 16 11:48:34 2014]  [<ffffffff81128f08>] ? touch_atime+0x116/0x123
[Sun Nov 16 11:48:34 2014]  [<ffffffff8111deaa>] filename_lookup.isra.46+0x21/0x59
[Sun Nov 16 11:48:34 2014]  [<ffffffff81120501>] user_path_at_empty+0x4e/0x8d
[Sun Nov 16 11:48:34 2014]  [<ffffffff8111a3ac>] ? pipe_read+0x262/0x274
[Sun Nov 16 11:48:34 2014]  [<ffffffff81112f11>] ? new_sync_read+0x72/0x99
[Sun Nov 16 11:48:34 2014]  [<ffffffff8112054c>] user_path_at+0xc/0xe
[Sun Nov 16 11:48:34 2014]  [<ffffffff81117587>] vfs_fstatat+0x49/0x8d
[Sun Nov 16 11:48:34 2014]  [<ffffffff811175e4>] vfs_lstat+0x19/0x1b
[Sun Nov 16 11:48:34 2014]  [<ffffffff81117718>] SyS_newlstat+0x15/0x2e
[Sun Nov 16 11:48:34 2014]  [<ffffffff813bb589>] ? lockdep_sys_exit_thunk+0x35/0x67
[Sun Nov 16 11:48:34 2014]  [<ffffffff81808412>] system_call_fastpath+0x16/0x1b
[Sun Nov 16 11:48:34 2014] Code: 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 55 f6 05 2b 98 91 01 01 48 89 e5 41 56 49 89 fe 41 55 41 54 53 48 8b 47 08 48 8b 40 68 <48> 8b 40 28 48 8b 98 20 06 00 00 74 0e 48 c7 c7 46 8a b2 81 31
[Sun Nov 16 11:48:34 2014] RIP  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:48:34 2014]  RSP <ffff88004cac3bd8>
[Sun Nov 16 11:48:34 2014] CR2: 0000000000000028
[Sun Nov 16 11:48:34 2014] ---[ end trace 177aaf47fd4980d3 ]---
[Sun Nov 16 11:48:43 2014] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[Sun Nov 16 11:48:43 2014] IP: [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:48:43 2014] PGD 42b9f067 PUD 3db16067 PMD 0
[Sun Nov 16 11:48:43 2014] Oops: 0000 [#3] SMP
[Sun Nov 16 11:48:43 2014] Modules linked in:
[Sun Nov 16 11:48:43 2014] CPU: 0 PID: 13249 Comm: sftp-server Tainted: G      D        3.17.1-gentoo20141023m-00002-gbe4fcc3 #2
[Sun Nov 16 11:48:43 2014] Hardware name: System manufacturer P5Q Premium, BIOS 1306 11/28/2013
[Sun Nov 16 11:48:43 2014] task: ffff880018a72850 ti: ffff88003b0b4000 task.ti: ffff88003b0b4000
[Sun Nov 16 11:48:43 2014] RIP: 0010:[<ffffffff812280c2>]  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:48:43 2014] RSP: 0018:ffff88003b0b7bd8  EFLAGS: 00010246
[Sun Nov 16 11:48:43 2014] RAX: 0000000000000000 RBX: ffff88003b0b7d08 RCX: 0000000000000001
[Sun Nov 16 11:48:43 2014] RDX: ffffffff81848d00 RSI: 0000000000000000 RDI: ffff88003b0b7d08
[Sun Nov 16 11:48:43 2014] RBP: ffff88003b0b7bf8 R08: 0000000000000000 R09: ffffffff813bb847
[Sun Nov 16 11:48:43 2014] R10: ffffffff813bb847 R11: 000100ff00000101 R12: 0000000000020000
[Sun Nov 16 11:48:43 2014] R13: 0000000000000000 R14: ffff88003b0b7d08 R15: ffff880074a63420
[Sun Nov 16 11:48:43 2014] FS:  00007f0d8d1fa700(0000) GS:ffff88007b400000(0000) knlGS:0000000000000000
[Sun Nov 16 11:48:43 2014] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Sun Nov 16 11:48:43 2014] CR2: 0000000000000028 CR3: 0000000079f4f000 CR4: 00000000000006f0
[Sun Nov 16 11:48:43 2014] Stack:
[Sun Nov 16 11:48:43 2014]  ffff88003b0b7d08 0000000000020000 0000000000000000 ffff880018a72850
[Sun Nov 16 11:48:43 2014]  ffff88003b0b7c58 ffffffff8111b9f6 ffff88003b0b7d08 0000000000000001
[Sun Nov 16 11:48:43 2014]  ffff88003b0b7c58 0000000200000000 ffff88003b0b7c38 ffff88003b0b7dc0
[Sun Nov 16 11:48:43 2014] Call Trace:
[Sun Nov 16 11:48:43 2014]  [<ffffffff8111b9f6>] follow_managed+0x139/0x218
[Sun Nov 16 11:48:43 2014]  [<ffffffff8111c335>] lookup_fast+0x271/0x2c3
[Sun Nov 16 11:48:43 2014]  [<ffffffff810802e2>] ? current_fs_time+0x11/0x39
[Sun Nov 16 11:48:43 2014]  [<ffffffff8111d94d>] path_lookupat+0xdb/0x617
[Sun Nov 16 11:48:43 2014]  [<ffffffff81128f08>] ? touch_atime+0x116/0x123
[Sun Nov 16 11:48:43 2014]  [<ffffffff8111deaa>] filename_lookup.isra.46+0x21/0x59
[Sun Nov 16 11:48:43 2014]  [<ffffffff81120501>] user_path_at_empty+0x4e/0x8d
[Sun Nov 16 11:48:43 2014]  [<ffffffff8111a3ac>] ? pipe_read+0x262/0x274
[Sun Nov 16 11:48:43 2014]  [<ffffffff81112f11>] ? new_sync_read+0x72/0x99
[Sun Nov 16 11:48:43 2014]  [<ffffffff8112054c>] user_path_at+0xc/0xe
[Sun Nov 16 11:48:43 2014]  [<ffffffff81117587>] vfs_fstatat+0x49/0x8d
[Sun Nov 16 11:48:43 2014]  [<ffffffff811175e4>] vfs_lstat+0x19/0x1b
[Sun Nov 16 11:48:43 2014]  [<ffffffff81117718>] SyS_newlstat+0x15/0x2e
[Sun Nov 16 11:48:43 2014]  [<ffffffff813bb589>] ? lockdep_sys_exit_thunk+0x35/0x67
[Sun Nov 16 11:48:43 2014]  [<ffffffff81808412>] system_call_fastpath+0x16/0x1b
[Sun Nov 16 11:48:43 2014] Code: 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 55 f6 05 2b 98 91 01 01 48 89 e5 41 56 49 89 fe 41 55 41 54 53 48 8b 47 08 48 8b 40 68 <48> 8b 40 28 48 8b 98 20 06 00 00 74 0e 48 c7 c7 46 8a b2 81 31
[Sun Nov 16 11:48:43 2014] RIP  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:48:43 2014]  RSP <ffff88003b0b7bd8>
[Sun Nov 16 11:48:43 2014] CR2: 0000000000000028
[Sun Nov 16 11:48:43 2014] ---[ end trace 177aaf47fd4980d4 ]---
[Sun Nov 16 11:49:07 2014] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[Sun Nov 16 11:49:07 2014] IP: [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:49:07 2014] PGD 977b067 PUD 79ec5067 PMD 0
[Sun Nov 16 11:49:07 2014] Oops: 0000 [#4] SMP
[Sun Nov 16 11:49:07 2014] Modules linked in:
[Sun Nov 16 11:49:07 2014] CPU: 0 PID: 13254 Comm: sftp-server Tainted: G      D        3.17.1-gentoo20141023m-00002-gbe4fcc3 #2
[Sun Nov 16 11:49:07 2014] Hardware name: System manufacturer P5Q Premium, BIOS 1306 11/28/2013
[Sun Nov 16 11:49:07 2014] task: ffff880074908810 ti: ffff88003b0b4000 task.ti: ffff88003b0b4000
[Sun Nov 16 11:49:07 2014] RIP: 0010:[<ffffffff812280c2>]  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:49:07 2014] RSP: 0018:ffff88003b0b7bd8  EFLAGS: 00010246
[Sun Nov 16 11:49:07 2014] RAX: 0000000000000000 RBX: ffff88003b0b7d08 RCX: 0000000000000001
[Sun Nov 16 11:49:07 2014] RDX: ffffffff81848d00 RSI: 0000000000000000 RDI: ffff88003b0b7d08
[Sun Nov 16 11:49:07 2014] RBP: ffff88003b0b7bf8 R08: 0000000000000000 R09: ffffffff813bb847
[Sun Nov 16 11:49:07 2014] R10: ffffffff813bb847 R11: 000000ff00000101 R12: 0000000000020000
[Sun Nov 16 11:49:07 2014] R13: 0000000000000000 R14: ffff88003b0b7d08 R15: ffff880074a63420
[Sun Nov 16 11:49:07 2014] FS:  00007fa9196bb700(0000) GS:ffff88007b400000(0000) knlGS:0000000000000000
[Sun Nov 16 11:49:07 2014] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Sun Nov 16 11:49:07 2014] CR2: 0000000000000028 CR3: 000000003668b000 CR4: 00000000000006f0
[Sun Nov 16 11:49:07 2014] Stack:
[Sun Nov 16 11:49:07 2014]  ffff88003b0b7d08 0000000000020000 0000000000000000 ffff880074908810
[Sun Nov 16 11:49:07 2014]  ffff88003b0b7c58 ffffffff8111b9f6 ffff88003b0b7d08 0000000000000001
[Sun Nov 16 11:49:07 2014]  ffff88003b0b7c58 0000000200000000 ffff88003b0b7c38 ffff88003b0b7dc0
[Sun Nov 16 11:49:07 2014] Call Trace:
[Sun Nov 16 11:49:07 2014]  [<ffffffff8111b9f6>] follow_managed+0x139/0x218
[Sun Nov 16 11:49:07 2014]  [<ffffffff8111c335>] lookup_fast+0x271/0x2c3
[Sun Nov 16 11:49:07 2014]  [<ffffffff810802e2>] ? current_fs_time+0x11/0x39
[Sun Nov 16 11:49:07 2014]  [<ffffffff8111d94d>] path_lookupat+0xdb/0x617
[Sun Nov 16 11:49:07 2014]  [<ffffffff81128f08>] ? touch_atime+0x116/0x123
[Sun Nov 16 11:49:07 2014]  [<ffffffff8111deaa>] filename_lookup.isra.46+0x21/0x59
[Sun Nov 16 11:49:07 2014]  [<ffffffff81120501>] user_path_at_empty+0x4e/0x8d
[Sun Nov 16 11:49:07 2014]  [<ffffffff8111a3ac>] ? pipe_read+0x262/0x274
[Sun Nov 16 11:49:07 2014]  [<ffffffff81112f11>] ? new_sync_read+0x72/0x99
[Sun Nov 16 11:49:07 2014]  [<ffffffff8112054c>] user_path_at+0xc/0xe
[Sun Nov 16 11:49:07 2014]  [<ffffffff81117587>] vfs_fstatat+0x49/0x8d
[Sun Nov 16 11:49:07 2014]  [<ffffffff811175e4>] vfs_lstat+0x19/0x1b
[Sun Nov 16 11:49:07 2014]  [<ffffffff81117718>] SyS_newlstat+0x15/0x2e
[Sun Nov 16 11:49:07 2014]  [<ffffffff813bb589>] ? lockdep_sys_exit_thunk+0x35/0x67
[Sun Nov 16 11:49:07 2014]  [<ffffffff81808412>] system_call_fastpath+0x16/0x1b
[Sun Nov 16 11:49:07 2014] Code: 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 55 f6 05 2b 98 91 01 01 48 89 e5 41 56 49 89 fe 41 55 41 54 53 48 8b 47 08 48 8b 40 68 <48> 8b 40 28 48 8b 98 20 06 00 00 74 0e 48 c7 c7 46 8a b2 81 31
[Sun Nov 16 11:49:07 2014] RIP  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:49:07 2014]  RSP <ffff88003b0b7bd8>
[Sun Nov 16 11:49:07 2014] CR2: 0000000000000028
[Sun Nov 16 11:49:07 2014] ---[ end trace 177aaf47fd4980d5 ]---
[Sun Nov 16 11:50:58 2014] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[Sun Nov 16 11:50:58 2014] IP: [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:50:58 2014] PGD 36796067 PUD 19149067 PMD 0
[Sun Nov 16 11:50:58 2014] Oops: 0000 [#5] SMP
[Sun Nov 16 11:50:58 2014] Modules linked in:
[Sun Nov 16 11:50:58 2014] CPU: 0 PID: 12914 Comm: sftp-server Tainted: G      D        3.17.1-gentoo20141023m-00002-gbe4fcc3 #2
[Sun Nov 16 11:50:58 2014] Hardware name: System manufacturer P5Q Premium, BIOS 1306 11/28/2013
[Sun Nov 16 11:50:58 2014] task: ffff88003db28c10 ti: ffff880042b34000 task.ti: ffff880042b34000
[Sun Nov 16 11:50:58 2014] RIP: 0010:[<ffffffff812280c2>]  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:50:58 2014] RSP: 0018:ffff880042b37bd8  EFLAGS: 00010246
[Sun Nov 16 11:50:58 2014] RAX: 0000000000000000 RBX: ffff880042b37d08 RCX: 0000000000000001
[Sun Nov 16 11:50:58 2014] RDX: ffffffff81848d00 RSI: 0000000000000000 RDI: ffff880042b37d08
[Sun Nov 16 11:50:58 2014] RBP: ffff880042b37bf8 R08: 0000000000000000 R09: ffffffff813bb847
[Sun Nov 16 11:50:58 2014] R10: ffffffff813bb847 R11: 0700000000000101 R12: 0000000000020000
[Sun Nov 16 11:50:58 2014] R13: 0000000000000000 R14: ffff880042b37d08 R15: ffff880074a63420
[Sun Nov 16 11:50:58 2014] FS:  00007f405880d700(0000) GS:ffff88007b400000(0000) knlGS:0000000000000000
[Sun Nov 16 11:50:58 2014] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Sun Nov 16 11:50:58 2014] CR2: 0000000000000028 CR3: 00000000317e2000 CR4: 00000000000006f0
[Sun Nov 16 11:50:58 2014] Stack:
[Sun Nov 16 11:50:58 2014]  ffff880042b37d08 0000000000020000 0000000000000000 ffff88003db28c10
[Sun Nov 16 11:50:58 2014]  ffff880042b37c58 ffffffff8111b9f6 ffff880042b37d08 0000000000000001
[Sun Nov 16 11:50:58 2014]  ffff880042b37c58 0000000000000000 ffff880042b37c38 ffff880042b37dc0
[Sun Nov 16 11:50:58 2014] Call Trace:
[Sun Nov 16 11:50:58 2014]  [<ffffffff8111b9f6>] follow_managed+0x139/0x218
[Sun Nov 16 11:50:58 2014]  [<ffffffff8111c335>] lookup_fast+0x271/0x2c3
[Sun Nov 16 11:50:58 2014]  [<ffffffff810802e2>] ? current_fs_time+0x11/0x39
[Sun Nov 16 11:50:58 2014]  [<ffffffff8111d94d>] path_lookupat+0xdb/0x617
[Sun Nov 16 11:50:58 2014]  [<ffffffff81128f08>] ? touch_atime+0x116/0x123
[Sun Nov 16 11:50:58 2014]  [<ffffffff8111deaa>] filename_lookup.isra.46+0x21/0x59
[Sun Nov 16 11:50:58 2014]  [<ffffffff81120501>] user_path_at_empty+0x4e/0x8d
[Sun Nov 16 11:50:58 2014]  [<ffffffff8111a3ac>] ? pipe_read+0x262/0x274
[Sun Nov 16 11:50:58 2014]  [<ffffffff81112f11>] ? new_sync_read+0x72/0x99
[Sun Nov 16 11:50:58 2014]  [<ffffffff8112054c>] user_path_at+0xc/0xe
[Sun Nov 16 11:50:58 2014]  [<ffffffff81117587>] vfs_fstatat+0x49/0x8d
[Sun Nov 16 11:50:58 2014]  [<ffffffff811175fc>] vfs_stat+0x16/0x18
[Sun Nov 16 11:50:58 2014]  [<ffffffff811176ea>] SyS_newstat+0x15/0x2e
[Sun Nov 16 11:50:58 2014]  [<ffffffff813bb589>] ? lockdep_sys_exit_thunk+0x35/0x67
[Sun Nov 16 11:50:58 2014]  [<ffffffff81808412>] system_call_fastpath+0x16/0x1b
[Sun Nov 16 11:50:58 2014] Code: 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 55 f6 05 2b 98 91 01 01 48 89 e5 41 56 49 89 fe 41 55 41 54 53 48 8b 47 08 48 8b 40 68 <48> 8b 40 28 48 8b 98 20 06 00 00 74 0e 48 c7 c7 46 8a b2 81 31
[Sun Nov 16 11:50:58 2014] RIP  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:50:58 2014]  RSP <ffff880042b37bd8>
[Sun Nov 16 11:50:58 2014] CR2: 0000000000000028
[Sun Nov 16 11:50:58 2014] ---[ end trace 177aaf47fd4980d6 ]---
[Sun Nov 16 11:51:31 2014] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[Sun Nov 16 11:51:31 2014] IP: [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:51:31 2014] PGD 18aed067 PUD 1b93a067 PMD 0
[Sun Nov 16 11:51:31 2014] Oops: 0000 [#6] SMP
[Sun Nov 16 11:51:31 2014] Modules linked in:
[Sun Nov 16 11:51:31 2014] CPU: 1 PID: 13261 Comm: sftp-server Tainted: G      D        3.17.1-gentoo20141023m-00002-gbe4fcc3 #2
[Sun Nov 16 11:51:31 2014] Hardware name: System manufacturer P5Q Premium, BIOS 1306 11/28/2013
[Sun Nov 16 11:51:31 2014] task: ffff88001b9a08d0 ti: ffff880074808000 task.ti: ffff880074808000
[Sun Nov 16 11:51:31 2014] RIP: 0010:[<ffffffff812280c2>]  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:51:31 2014] RSP: 0018:ffff88007480bbd8  EFLAGS: 00010246
[Sun Nov 16 11:51:31 2014] RAX: 0000000000000000 RBX: ffff88007480bd08 RCX: 0000000000000001
[Sun Nov 16 11:51:31 2014] RDX: ffffffff81848d00 RSI: 0000000000000000 RDI: ffff88007480bd08
[Sun Nov 16 11:51:31 2014] RBP: ffff88007480bbf8 R08: 0000000000000000 R09: ffffffff813bb847
[Sun Nov 16 11:51:31 2014] R10: ffffffff813bb847 R11: 000000ff00000101 R12: 0000000000020000
[Sun Nov 16 11:51:31 2014] R13: 0000000000000000 R14: ffff88007480bd08 R15: ffff880074a63420
[Sun Nov 16 11:51:31 2014] FS:  00007f6a5e0db700(0000) GS:ffff88007b600000(0000) knlGS:0000000000000000
[Sun Nov 16 11:51:31 2014] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Sun Nov 16 11:51:31 2014] CR2: 0000000000000028 CR3: 000000004cbe9000 CR4: 00000000000006e0
[Sun Nov 16 11:51:31 2014] Stack:
[Sun Nov 16 11:51:31 2014]  ffff88007480bd08 0000000000020000 0000000000000000 ffff88001b9a08d0
[Sun Nov 16 11:51:31 2014]  ffff88007480bc58 ffffffff8111b9f6 ffff88007480bd08 0000000000000001
[Sun Nov 16 11:51:31 2014]  ffff88007480bc58 0000000200000000 ffff88007480bc38 ffff88007480bdc0
[Sun Nov 16 11:51:31 2014] Call Trace:
[Sun Nov 16 11:51:31 2014]  [<ffffffff8111b9f6>] follow_managed+0x139/0x218
[Sun Nov 16 11:51:31 2014]  [<ffffffff8111c335>] lookup_fast+0x271/0x2c3
[Sun Nov 16 11:51:31 2014]  [<ffffffff810802e2>] ? current_fs_time+0x11/0x39
[Sun Nov 16 11:51:31 2014]  [<ffffffff8111d94d>] path_lookupat+0xdb/0x617
[Sun Nov 16 11:51:31 2014]  [<ffffffff81128f08>] ? touch_atime+0x116/0x123
[Sun Nov 16 11:51:31 2014]  [<ffffffff8111deaa>] filename_lookup.isra.46+0x21/0x59
[Sun Nov 16 11:51:31 2014]  [<ffffffff81120501>] user_path_at_empty+0x4e/0x8d
[Sun Nov 16 11:51:31 2014]  [<ffffffff8111a3ac>] ? pipe_read+0x262/0x274
[Sun Nov 16 11:51:31 2014]  [<ffffffff81112f11>] ? new_sync_read+0x72/0x99
[Sun Nov 16 11:51:31 2014]  [<ffffffff8112054c>] user_path_at+0xc/0xe
[Sun Nov 16 11:51:31 2014]  [<ffffffff81117587>] vfs_fstatat+0x49/0x8d
[Sun Nov 16 11:51:31 2014]  [<ffffffff811175e4>] vfs_lstat+0x19/0x1b
[Sun Nov 16 11:51:31 2014]  [<ffffffff81117718>] SyS_newlstat+0x15/0x2e
[Sun Nov 16 11:51:31 2014]  [<ffffffff813bb589>] ? lockdep_sys_exit_thunk+0x35/0x67
[Sun Nov 16 11:51:31 2014]  [<ffffffff81808412>] system_call_fastpath+0x16/0x1b
[Sun Nov 16 11:51:31 2014] Code: 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 55 f6 05 2b 98 91 01 01 48 89 e5 41 56 49 89 fe 41 55 41 54 53 48 8b 47 08 48 8b 40 68 <48> 8b 40 28 48 8b 98 20 06 00 00 74 0e 48 c7 c7 46 8a b2 81 31
[Sun Nov 16 11:51:31 2014] RIP  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:51:31 2014]  RSP <ffff88007480bbd8>
[Sun Nov 16 11:51:31 2014] CR2: 0000000000000028
[Sun Nov 16 11:51:31 2014] ---[ end trace 177aaf47fd4980d7 ]---
[Sun Nov 16 11:51:50 2014] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[Sun Nov 16 11:51:50 2014] IP: [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:51:50 2014] PGD 5fffe067 PUD 963d067 PMD 0
[Sun Nov 16 11:51:50 2014] Oops: 0000 [#7] SMP
[Sun Nov 16 11:51:50 2014] Modules linked in:
[Sun Nov 16 11:51:50 2014] CPU: 1 PID: 13294 Comm: sftp-server Tainted: G      D        3.17.1-gentoo20141023m-00002-gbe4fcc3 #2
[Sun Nov 16 11:51:50 2014] Hardware name: System manufacturer P5Q Premium, BIOS 1306 11/28/2013
[Sun Nov 16 11:51:50 2014] task: ffff880078bde210 ti: ffff880074808000 task.ti: ffff880074808000
[Sun Nov 16 11:51:50 2014] RIP: 0010:[<ffffffff812280c2>]  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:51:50 2014] RSP: 0018:ffff88007480bbd8  EFLAGS: 00010246
[Sun Nov 16 11:51:50 2014] RAX: 0000000000000000 RBX: ffff88007480bd08 RCX: 0000000000000001
[Sun Nov 16 11:51:50 2014] RDX: ffffffff81848d00 RSI: 0000000000000000 RDI: ffff88007480bd08
[Sun Nov 16 11:51:50 2014] RBP: ffff88007480bbf8 R08: 0000000000000000 R09: ffffffff813bb847
[Sun Nov 16 11:51:50 2014] R10: ffffffff813bb847 R11: 000000ff00000101 R12: 0000000000020000
[Sun Nov 16 11:51:50 2014] R13: 0000000000000000 R14: ffff88007480bd08 R15: ffff880074a63420
[Sun Nov 16 11:51:50 2014] FS:  00007f2d6af21700(0000) GS:ffff88007b600000(0000) knlGS:0000000000000000
[Sun Nov 16 11:51:50 2014] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Sun Nov 16 11:51:50 2014] CR2: 0000000000000028 CR3: 000000006da1f000 CR4: 00000000000006e0
[Sun Nov 16 11:51:50 2014] Stack:
[Sun Nov 16 11:51:50 2014]  ffff88007480bd08 0000000000020000 0000000000000000 ffff880078bde210
[Sun Nov 16 11:51:50 2014]  ffff88007480bc58 ffffffff8111b9f6 ffff88007480bd08 0000000000000001
[Sun Nov 16 11:51:50 2014]  ffff88007480bc58 0000000200000000 ffff88007480bc38 ffff88007480bdc0
[Sun Nov 16 11:51:50 2014] Call Trace:
[Sun Nov 16 11:51:50 2014]  [<ffffffff8111b9f6>] follow_managed+0x139/0x218
[Sun Nov 16 11:51:50 2014]  [<ffffffff8111c335>] lookup_fast+0x271/0x2c3
[Sun Nov 16 11:51:50 2014]  [<ffffffff8111d94d>] path_lookupat+0xdb/0x617
[Sun Nov 16 11:51:50 2014]  [<ffffffff81128f08>] ? touch_atime+0x116/0x123
[Sun Nov 16 11:51:50 2014]  [<ffffffff8111deaa>] filename_lookup.isra.46+0x21/0x59
[Sun Nov 16 11:51:50 2014]  [<ffffffff81120501>] user_path_at_empty+0x4e/0x8d
[Sun Nov 16 11:51:50 2014]  [<ffffffff8111a3ac>] ? pipe_read+0x262/0x274
[Sun Nov 16 11:51:50 2014]  [<ffffffff81112f11>] ? new_sync_read+0x72/0x99
[Sun Nov 16 11:51:50 2014]  [<ffffffff8112054c>] user_path_at+0xc/0xe
[Sun Nov 16 11:51:50 2014]  [<ffffffff81117587>] vfs_fstatat+0x49/0x8d
[Sun Nov 16 11:51:50 2014]  [<ffffffff811175e4>] vfs_lstat+0x19/0x1b
[Sun Nov 16 11:51:50 2014]  [<ffffffff81117718>] SyS_newlstat+0x15/0x2e
[Sun Nov 16 11:51:50 2014]  [<ffffffff813bb589>] ? lockdep_sys_exit_thunk+0x35/0x67
[Sun Nov 16 11:51:50 2014]  [<ffffffff81808412>] system_call_fastpath+0x16/0x1b
[Sun Nov 16 11:51:50 2014] Code: 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 55 f6 05 2b 98 91 01 01 48 89 e5 41 56 49 89 fe 41 55 41 54 53 48 8b 47 08 48 8b 40 68 <48> 8b 40 28 48 8b 98 20 06 00 00 74 0e 48 c7 c7 46 8a b2 81 31
[Sun Nov 16 11:51:50 2014] RIP  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:51:50 2014]  RSP <ffff88007480bbd8>
[Sun Nov 16 11:51:50 2014] CR2: 0000000000000028
[Sun Nov 16 11:51:50 2014] ---[ end trace 177aaf47fd4980d8 ]---
[Sun Nov 16 11:52:25 2014] BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
[Sun Nov 16 11:52:25 2014] IP: [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:52:25 2014] PGD 6e599067 PUD 78ffc067 PMD 0
[Sun Nov 16 11:52:25 2014] Oops: 0000 [#8] SMP
[Sun Nov 16 11:52:25 2014] Modules linked in:
[Sun Nov 16 11:52:25 2014] CPU: 1 PID: 13303 Comm: sftp-server Tainted: G      D        3.17.1-gentoo20141023m-00002-gbe4fcc3 #2
[Sun Nov 16 11:52:25 2014] Hardware name: System manufacturer P5Q Premium, BIOS 1306 11/28/2013
[Sun Nov 16 11:52:25 2014] task: ffff88006dacc250 ti: ffff880074808000 task.ti: ffff880074808000
[Sun Nov 16 11:52:25 2014] RIP: 0010:[<ffffffff812280c2>]  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:52:25 2014] RSP: 0018:ffff88007480bbd8  EFLAGS: 00010246
[Sun Nov 16 11:52:25 2014] RAX: 0000000000000000 RBX: ffff88007480bd08 RCX: 0000000000000001
[Sun Nov 16 11:52:25 2014] RDX: ffffffff81848d00 RSI: 0000000000000000 RDI: ffff88007480bd08
[Sun Nov 16 11:52:25 2014] RBP: ffff88007480bbf8 R08: 0000000000000000 R09: ffffffff813bb847
[Sun Nov 16 11:52:25 2014] R10: ffffffff813bb847 R11: 000000ff00000101 R12: 0000000000020000
[Sun Nov 16 11:52:25 2014] R13: 0000000000000000 R14: ffff88007480bd08 R15: ffff880074a63420
[Sun Nov 16 11:52:25 2014] FS:  00007f3137655700(0000) GS:ffff88007b600000(0000) knlGS:0000000000000000
[Sun Nov 16 11:52:25 2014] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[Sun Nov 16 11:52:25 2014] CR2: 0000000000000028 CR3: 000000003164c000 CR4: 00000000000006e0
[Sun Nov 16 11:52:25 2014] Stack:
[Sun Nov 16 11:52:25 2014]  ffff88007480bd08 0000000000020000 0000000000000000 ffff88006dacc250
[Sun Nov 16 11:52:25 2014]  ffff88007480bc58 ffffffff8111b9f6 ffff88007480bd08 0000000000000001
[Sun Nov 16 11:52:25 2014]  ffff88007480bc58 0000000200000000 ffff88007480bc38 ffff88007480bdc0
[Sun Nov 16 11:52:25 2014] Call Trace:
[Sun Nov 16 11:52:25 2014]  [<ffffffff8111b9f6>] follow_managed+0x139/0x218
[Sun Nov 16 11:52:25 2014]  [<ffffffff8111c335>] lookup_fast+0x271/0x2c3
[Sun Nov 16 11:52:25 2014]  [<ffffffff8111d94d>] path_lookupat+0xdb/0x617
[Sun Nov 16 11:52:25 2014]  [<ffffffff81128f08>] ? touch_atime+0x116/0x123
[Sun Nov 16 11:52:25 2014]  [<ffffffff8111deaa>] filename_lookup.isra.46+0x21/0x59
[Sun Nov 16 11:52:25 2014]  [<ffffffff81120501>] user_path_at_empty+0x4e/0x8d
[Sun Nov 16 11:52:25 2014]  [<ffffffff8111a3ac>] ? pipe_read+0x262/0x274
[Sun Nov 16 11:52:25 2014]  [<ffffffff81112f11>] ? new_sync_read+0x72/0x99
[Sun Nov 16 11:52:25 2014]  [<ffffffff8112054c>] user_path_at+0xc/0xe
[Sun Nov 16 11:52:25 2014]  [<ffffffff81117587>] vfs_fstatat+0x49/0x8d
[Sun Nov 16 11:52:25 2014]  [<ffffffff811175e4>] vfs_lstat+0x19/0x1b
[Sun Nov 16 11:52:25 2014]  [<ffffffff81117718>] SyS_newlstat+0x15/0x2e
[Sun Nov 16 11:52:25 2014]  [<ffffffff813bb589>] ? lockdep_sys_exit_thunk+0x35/0x67
[Sun Nov 16 11:52:25 2014]  [<ffffffff81808412>] system_call_fastpath+0x16/0x1b
[Sun Nov 16 11:52:25 2014] Code: 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 55 f6 05 2b 98 91 01 01 48 89 e5 41 56 49 89 fe 41 55 41 54 53 48 8b 47 08 48 8b 40 68 <48> 8b 40 28 48 8b 98 20 06 00 00 74 0e 48 c7 c7 46 8a b2 81 31
[Sun Nov 16 11:52:25 2014] RIP  [<ffffffff812280c2>] nfs_d_automount+0x1d/0x173
[Sun Nov 16 11:52:25 2014]  RSP <ffff88007480bbd8>
[Sun Nov 16 11:52:25 2014] CR2: 0000000000000028
[Sun Nov 16 11:52:25 2014] ---[ end trace 177aaf47fd4980d9 ]---
Comment 15 Dwayne Hart 2014-12-11 22:21:08 UTC 
Hi,

This issue is still present with the changes made to the 3.17.3 kernel.

[Thu Dec 11 11:10:47 2014] BUG: Dentry ffff88002a38b690{i=3b6e139,n=.sh_history}  still in use (1) [unmount of nfs4 0:95]
[Thu Dec 11 11:10:47 2014] ------------[ cut here ]------------
[Thu Dec 11 11:10:47 2014] WARNING: CPU: 1 PID: 26832 at fs/dcache.c:1318 umount_check+0x77/0x7b()
[Thu Dec 11 11:10:47 2014] Modules linked in:
[Thu Dec 11 11:10:47 2014] CPU: 1 PID: 26832 Comm: umount.nfs4 Tainted: G      D        3.17.3-gentoo20141125-00002-g07770bd #2
[Thu Dec 11 11:10:47 2014] Hardware name: System manufacturer P5Q Premium, BIOS 1306 11/28/2013
[Thu Dec 11 11:10:47 2014]  0000000000000526 ffff880054533cc8 ffffffff81802385 ffffffff81075a81
[Thu Dec 11 11:10:47 2014]  0000000000000000 ffff880054533d08 ffffffff8103c583 ffff880054533d30
[Thu Dec 11 11:10:47 2014]  ffffffff81125c40 ffff8800716cba90 0000000000007e88 ffff880045e6e601
[Thu Dec 11 11:10:47 2014] Call Trace:
[Thu Dec 11 11:10:47 2014]  [<ffffffff81802385>] dump_stack+0x46/0x58
[Thu Dec 11 11:10:47 2014]  [<ffffffff81075a81>] ? console_unlock+0x33f/0x36a
[Thu Dec 11 11:10:47 2014]  [<ffffffff8103c583>] warn_slowpath_common+0x7c/0x96
[Thu Dec 11 11:10:47 2014]  [<ffffffff81125c40>] ? umount_check+0x77/0x7b
[Thu Dec 11 11:10:47 2014]  [<ffffffff8103c5b2>] warn_slowpath_null+0x15/0x17
[Thu Dec 11 11:10:47 2014]  [<ffffffff81125c40>] umount_check+0x77/0x7b
[Thu Dec 11 11:10:47 2014]  [<ffffffff81124ade>] d_walk+0x115/0x2d4
[Thu Dec 11 11:10:47 2014]  [<ffffffff8112669c>] ? do_one_tree+0x22/0x36
[Thu Dec 11 11:10:47 2014]  [<ffffffff81125bc9>] ? d_instantiate_unique+0x68/0x68
[Thu Dec 11 11:10:47 2014]  [<ffffffff8112669c>] do_one_tree+0x22/0x36
[Thu Dec 11 11:10:47 2014]  [<ffffffff81126b95>] shrink_dcache_for_umount+0x59/0x6b
[Thu Dec 11 11:10:47 2014]  [<ffffffff8111558e>] generic_shutdown_super+0x1e/0xed
[Thu Dec 11 11:10:47 2014]  [<ffffffff811156d0>] kill_anon_super+0xe/0x19
[Thu Dec 11 11:10:47 2014]  [<ffffffff8121f699>] nfs_kill_super+0x12/0x1e
[Thu Dec 11 11:10:47 2014]  [<ffffffff81115c12>] deactivate_locked_super+0x36/0x4b
[Thu Dec 11 11:10:47 2014]  [<ffffffff81116301>] deactivate_super+0x3a/0x3e
[Thu Dec 11 11:10:47 2014]  [<ffffffff8112d2f4>] mntput_no_expire+0x1b0/0x1d2
[Thu Dec 11 11:10:47 2014]  [<ffffffff8112e6ed>] ? SyS_umount+0x3af/0x3c4
[Thu Dec 11 11:10:47 2014]  [<ffffffff8112e6ed>] SyS_umount+0x3af/0x3c4
[Thu Dec 11 11:10:47 2014]  [<ffffffff81809d12>] ? system_call_fastpath+0x16/0x1b
[Thu Dec 11 11:10:47 2014]  [<ffffffff810f0a76>] ? vm_munmap+0x4e/0x5e
[Thu Dec 11 11:10:47 2014]  [<ffffffff8112d144>] ? mnt_get_count+0x53/0x53
[Thu Dec 11 11:10:47 2014]  [<ffffffff81809d12>] system_call_fastpath+0x16/0x1b
[Thu Dec 11 11:10:47 2014] ---[ end trace 5000a09226414362 ]---
[Thu Dec 11 11:10:47 2014] VFS: Busy inodes after unmount of 0:95. Self-destruct in 5 seconds.  Have a nice day...
Comment 16 [account disabled by administrator] 2016-04-04 20:19:36 UTC 
Can you try adding this line
nfs_umount_begin(s);
on line 2661, in the function nfs_kill_super to see if this fixes your issue.
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