New: BUG: unable to handle kernel NULL pointer dereference
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: [email protected]
ReportedBy: [email protected]
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.
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
https://bugzilla.kernel.org/show_bug.cgi?id=51391
Theodore Tso <[email protected]> changed:
What |Removed |Added
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CC| |[email protected]
--- Comment #1 from Theodore Tso <[email protected]> 2012-12-07 16:15:25 --- I don't see the attached kernel logs; can you please attach it to this bug report?
Thanks!!
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=51391
Alan <[email protected]> changed:
What |Removed |Added
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Status|NEW |NEEDINFO
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=51391
--- Comment #2 from Karen <[email protected]> 2012-12-07 16:25:31 --- Created an attachment (id=88611)
--> (https://bugzilla.kernel.org/attachment.cgi?id=88611)
kernel log file
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=51391
--- Comment #3 from Theodore Tso <[email protected]> 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.?
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=51391
--- Comment #4 from Theodore Tso <[email protected]> 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?
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=51391
--- Comment #5 from Karen <[email protected]> 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.
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=51391
--- Comment #6 from Theodore Tso <[email protected]> 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.
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=51391
--- Comment #7 from Karen <[email protected]> 2012-12-07 18:15:41 --- I was using a base kernel which is coming with Ubuntu 12.04
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=51391
Theodore Tso <[email protected]> changed:
What |Removed |Added
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Status|NEEDINFO |REJECTED
Resolution| |UNREPRODUCIBLE--- Comment #8 from Theodore Tso <[email protected]> 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.
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=51391
--- Comment #9 from Karen <[email protected]> 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.
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[Bug 51391] BUG: unable to handle kernel NULL pointer dereference
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=51391
Alexey Khoroshilov <[email protected]> changed:
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CC| |[email protected] | |g
--- Comment #10 from Alexey Khoroshilov <[email protected]> 2013-02-11 10:04:51 --- (In reply to comment #4)
Quoted 2 lines
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.
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