Re: kernel 2.6.39 (user mode linux) crashes (2.6.38 works fine)

From: Toralf Förster
Date: Fri May 20 2011 - 18:54:55 EST

Steven Rostedt wrote at 18:11:36
> Could you apply these patches:
> 2092e6be WARN_ON_SMP(): Allow use in if() statements on UP
> 29096202 futex: Fix WARN_ON() test for UP
> On top of this commit, and see if the problem goes away. What could have
> happened, is that you have two bugs, with one of them fixed. If the git
> bisect stumbled on this bug, it will show this one, even though later
> on, this code was fixed. If you apply the above two patches and it works
> again, then this isn't the bug you are looking for.

I bisected it again and applied at every step those 2 commits, if commit
2e12978 was in the source too.

Furthermore it was necessary to use a fresh instance of firefox every time to
reproduce a now shomehow changed issue: the UML system wasn't longer
reachable, neither ping nor ssh into it was possible as soon as I tried to
point firefox to https://n22_uml/phpmyadmin/ and no crash occured any longer.
Furthermore a previously opened ssh session to that UML hangs completely.

Bisecting gave :

git bisect badd123375425d7df4b6081a631fc1203fceafa59b2 is the first bad commit
commit d123375425d7df4b6081a631fc1203fceafa59b2
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Wed Jan 26 21:32:01 2011 +0100

rwsem: Remove redundant asmregparm annotation

Peter Zijlstra pointed out, that the only user of asmregparm (x86) is
compiling the kernel already with -mregparm=3. So the annotation of
the rwsem functions is redundant. Remove it.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Matt Turner <mattst88@xxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
Cc: David Miller <davem@xxxxxxxxxxxxx>
Cc: Chris Zankel <chris@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

:040000 040000 f373822625e4f5d03d89997cc9f06ef0e21c6d08
272479d3450a4924f3ad2d06a058d77c577ec0d4 M include
:040000 040000 9294321acb9db51e4db72b8e7c95fbd1531a7f26
393fc63299ae482792439384485618a492619787 M lib


Toralf Förster
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