Red Hat Bugzilla – Bug 433192
Consecutively running LTP mtest01 results in lock up
Last modified: 2009-01-09 02:39:45 EST
Description of problem:
Running the test 'mtest01 -p80 -w' from Linux Test Project consecutively a bunch
of times locks up my machine.
* Happens after 15 to 30 minutes
* Network is down, input isn't possible anymore
* No output, nothing in the logs
* Motherboard Tyan S2927
* 2x Opteron 2212
* 8GB RAM + 8GB swap
Version-Release number of selected component (if applicable):
LTP version: 20080131
Failing kernel package:
Other kernels tested that don't show this behavior:
* kernel-2.6.24-0.102.rc5.git3.fc9 (built from CVS)
* kernel-22.214.171.124-4.fc8 (built from CVS)
Steps to Reproduce:
* Fetch LTP sources
* Run make; make install
* Do something along the lines
while true; do
/root/ltp-full-20080131/testcases/bin/mtest01 -p80 -w
I gave up tracking this down in detail. An update to a 2.6.24 based kernel which
seems to be planned would fix this anyway. The box is available for further
126.96.36.199-7 has been submitted to updates-testing.
* 188.8.131.52-7 failed after 18 min
* Retesting with kernel-184.108.40.206-4.fc8 failed, too
* Currently running the test on kernel-2.6.25-0.40.rc1.git2.fc9 again
- looks good so far (35 mins)
- I'll keep it running at least another 9 hours
Maybe I forgot to rebuild LTP with the appropriate kernel-headers installed.
Will do some more investigation as my time permits.
(In reply to comment #2)
> * Currently running the test on kernel-2.6.25-0.40.rc1.git2.fc9 again
It ran for more than 12 hours without failure.
> Maybe I forgot to rebuild LTP with the appropriate kernel-headers installed.
Verified this: It doesn't matter which one is installed. No clue why 2.6.24-4
did work once.
Over the weekend I ran a bisect between 2.6.24 and 2.6.25-rc1 (Linus' tree) with
configs derived off of Fedora kernel ones. I think I've found the commit that
fixed this problem, although it's quite surprising to me:
Author: Greg Kroah-Hartman <firstname.lastname@example.org>
Date: Fri Nov 2 13:20:40 2007 -0700
kset: convert efivars to use kset_create for the vars sub-subsystem.
Dynamically create the kset instead of declaring it statically.
This one ran for more than 9 hours without failure, whereas the commit before
(89a07e34b16d9dcdf0a9ada3ca0c9a506b490c8f) failed during the first iteration,
and the third one before (334c6307543a2b8af730a422f466d5f9442b606a) failed after
I have no clue why efivars.c does matter on a system without EFI. I'm going to
put Matt Domsch on CC to get more info.
I saved the bisect log and a hand pasted scribbling of the proceedings in case
you need it. All of the 14 kernel builds are still available on the test box, too.
(In reply to comment #3)
> I have no clue why efivars.c does matter on a system without EFI. I'm going to
> put Matt Domsch on CC to get more info.
Sorry for the noise Matt, I messed something up. It cannot and it does not have
something to do with EFI.
The bug gets triggered with configs derived from Fedora 2.6.24, and goes away
with configs derived from Fedora 2.6.25-rc1. Obviously, I switched between those
in the middle of the bisect.
Back to try and fail.
Now I'm absolutely sure about what... well, seems to hide the problem. With the
following debug options turned on my box doesn't lock up anymore:
Any suggestions how to proceed further?
(In reply to comment #5)
> Now I'm absolutely sure about what... well, seems to hide the problem. With the
> following debug options turned on my box doesn't lock up anymore:
> Any suggestions how to proceed further?
Try disabling them one at a time until it breaks...
(In reply to comment #6)
> Try disabling them one at a time until it breaks...
First I disabled CONFIG_DEBUG_LOCK_ALLOC, CONFIG_LOCKDEP, and CONFIG_STACKTRACE,
as these depend on the other two. This configuration ran for 9+ hours. Then I
additionally disabled CONFIG_DEBUG_SPINLOCK and this one broke after 10 minutes.
So I think CONFIG_DEBUG_SPINLOCK it is.
X86 spinlocks have been rewritten in 2.6.25-rc. Can you try that with
220.127.116.11-12.fc8.i686 seems to be okay, it ran for over an hour without any problems.
(In reply to comment #8)
> X86 spinlocks have been rewritten in 2.6.25-rc. Can you try that with
> DEBUG_SPINLOCK disabled?
Linus' tree as of yesterday seems to work. It ran for more than 10 hours now.
> 18.104.22.168-12.fc8.i686 seems to be okay, it ran for over an hour without any
I'll try that one during the weekend.
(In reply to comment #9)
> > 22.214.171.124-12.fc8.i686 seems to be okay, it ran for over an hour without any
No, 126.96.36.199-12.fc8.x86_64 locked up after 35 minutes here. Looks like another
round of bisect...
But i686 seems to be okay.
Can you try the NMI watchdog to see if it catches the hang? (Try booting with
either "nmi_watchdog=1" or "nmi_watchdog=2" option.)
Created attachment 296710 [details]
Serial console output
Yes! nmi_watchdog catched it. See attachment.
Bisect does indeed indicate that the spinlock changes from Nick Piggin are
getting 2.6.25-rc to work (commit 314cdbefd1fd0a7acf3780e9628465b77ea6a836). At
least I'm two builds away from it now.
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