[Bug 51391] New: BUG: unable to handle kernel NULL pointer dereference

[Bug 51391] New: BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391

           Summary: BUG: unable to handle kernel NULL pointer dereference
           Product: File System
           Version: 2.5
    Kernel Version: 3.2.0-29-generic
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: ext4
        AssignedTo: fs_ext4@kernel-bugs.osdl.org
        ReportedBy: ktsirunyan@gmail.com
        Regression: No


Architecture :  x86_64 emulated by VirtualBox version 4.1.2_Ubuntu r38459
Distributive :     Ubuntu 12.04
File System  :     Ext4
Detected by the Spruce System (http://linuxtesting.org/spruce)
Bug appears when trying to mount a device with MS_NODEV flag attempted.
See the kernel message attached below.

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391


Theodore Tso <tytso@mit.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tytso@mit.edu




--- Comment #1 from Theodore Tso <tytso@mit.edu>  2012-12-07 16:15:25 ---
I don't see the attached kernel logs; can you please attach it to this bug
report?

Thanks!!

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391


Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |NEEDINFO
                 CC|                            |alan@lxorguk.ukuu.org.uk




-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391





--- Comment #2 from Karen <ktsirunyan@gmail.com>  2012-12-07 16:25:31 ---
Created an attachment (id=88611)
 --> (https://bugzilla.kernel.org/attachment.cgi?id=88611)
kernel log file

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391





--- Comment #3 from Theodore Tso <tytso@mit.edu>  2012-12-07 17:10:50 ---
I just built 3.2.29, and running under KVM, I created a file system, mounted it
with -o nodev, and then unmounted it.  It didn't crash.

I then mounted it without nodev, ran "mknod /mnt/null c 3 1" to create a
/dev/null character device, unmounted the file system, remounted it with -o
nodev, tried writing to /mnt/null, which failed as it should, and then
unmounted the file system.   Still no crash.

Can you tell me if there was anything else special about how you ran your test?
 Did it fail right on the mount?  Was this the root file system that you were
testing trying to mount -o nodev, etc.?

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391





--- Comment #4 from Theodore Tso <tytso@mit.edu>  2012-12-07 17:12:21 ---
Hmm, I looked at the stack trace again, and I see "sys_inotify_rm_watch" in the
stack trace.  I wonder if this is a generic VFS-level inotify bug, perhaps?   I
don't have an easy way of setting up an inotify in my bare-bones KVM
environment.  Can you tell me a bit more about your environment and what you
might be using that might be setting an inotify on something on your file
system?

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391





--- Comment #5 from Karen <ktsirunyan@gmail.com>  2012-12-07 17:39:52 ---
I was executing a system called Spruce(which is performing a verification of
Linux file System drivers). The crash come out on the test which is performing
a mount of the current device on the current mount point with MS_NODEV flag
activated. Also program was compiled as a 32-bit program (with Ubuntu Multilib)
but on 64 bit architecture. Hope that helps.

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391





--- Comment #6 from Theodore Tso <tytso@mit.edu>  2012-12-07 18:04:22 ---
Well, I was using a 64-bit kernel and a 32-bit mount program, so that
replicates what you are doing, and a "mount -o nodev" will use MS_NODEV.  And
I'm using a stock 3.2.29 kernel.

At this point I don't know what to tell you.  I can't duplicate the problem
here.  If you can give me an easy reproduction that you can run by hand, great.
 Otherwise, I'm going to have to close this out as not reproducible.

The other possibility is this is an Ubuntu bug.  Are you using a stock kernel,
or is this a kernel with Ubuntu's "value added patches"?   If this is not a
stock kernel, I'd advise that you submit this bug to Ubuntu.

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391





--- Comment #7 from Karen <ktsirunyan@gmail.com>  2012-12-07 18:15:41 ---
I was using a base kernel which is coming with Ubuntu 12.04

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391


Theodore Tso <tytso@mit.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEEDINFO                    |REJECTED
         Resolution|                            |UNREPRODUCIBLE




--- Comment #8 from Theodore Tso <tytso@mit.edu>  2012-12-07 20:13:05 ---
Can you replicate the problem **without** using Spruce?

In any case, I would suggest sending a bug report with Canonical, since this is
a Ubuntu kernel --- and despite my best efforts, I can not replicate the
problem as you have described it on a stock 3.2.29 or 3.7-rc4 development
kernel.

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391





--- Comment #9 from Karen <ktsirunyan@gmail.com>  2012-12-10 08:23:04 ---
I couldn't replicate the problem without Spruce yet, but still I am trying.

Also I want to notice that You are using 3.2.29 but my kernel is 3.2.0.-29.
I will try to send this problem to Canonical too.

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.

[Bug 51391] BUG: unable to handle kernel NULL pointer dereference

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=51391


Alexey Khoroshilov <khoroshilov@linuxtesting.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |khoroshilov@linuxtesting.or
                   |                            |g




--- Comment #10 from Alexey Khoroshilov <khoroshilov@linuxtesting.org>  2013-02-11 10:04:51 ---
(In reply to comment #4)
> Hmm, I looked at the stack trace again, and I see "sys_inotify_rm_watch" in the
> stack trace.  I wonder if this is a generic VFS-level inotify bug, perhaps?   

It looks like it is actually a data race in VFS layer:
https://patchwork.kernel.org/patch/1685431/

We observed the same issue with JFS file system.

-- 
Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are watching the assignee of the bug.