[uml-devel] Kernel idles in loop after loading IPv4

[uml-devel] Kernel idles in loop after loading IPv4

[Phil Nadeau]

Hello UML developers,

I'm trying to use UML to set up a simulator for a high-availability
cluster. I encounter the following unexpected behavior -

On any kernel that I compile with IPv4 support, the kernel will stop
intializing drivers after loading IPv4 support. The last message I see
from the kernel is:
NET: Registered protocol family 2

Compiling with debug allows me to single-step through the kernel. I've
traced execution from inet_init(), to synchronize_net(), to
synchronize_kernel(), to a call to wait_for_completion(), to
switch_to_tt(), after which the kernel spends all its time in the idle
loop. This happens whether I'm using SKAS or TT mode.

Host kernel is 2.6.1 with Stephen William's 2.6.1 SKAS patch (thanks
Stephen). Guest kernel is 2.6.1 with the latest patch from Sourceforge
(January 15th), without modules, and with nearly everything disabled at
compile except core functionality and IPv4.

I've tried to find similar cases in the FAQ's and the list archives, but
I'm not seeing anything. It seems like the kernel is waiting for an
event related to IPv4 initialization that it never gets, but I'm not
familiar enough with the kernel proper to know what that might be. Does
anyone have any ideas?

Thanks in advance.

-- 
Phil Nadeau
Software Services Manager
phil.nadeau@innercite.com
(916)932-3200, (800)921-5513



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Re: [uml-devel] Kernel idles in loop after loading IPv4

[Steven James]

Greetings,

I ran into that as well, but didn't have time to do much about it. As a
further datapoint, if I disable all net support and pass it
init=/bin/bash, I get the bash prompt (ubd filesystems do get
checked/mounted) but then it goes into the idle loop and stays there.

G'day,
sjames


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On Tue, 27 Jan 2004, Phil Nadeau wrote:

> Hello UML developers,
>
> I'm trying to use UML to set up a simulator for a high-availability
> cluster. I encounter the following unexpected behavior -
>
> On any kernel that I compile with IPv4 support, the kernel will stop
> intializing drivers after loading IPv4 support. The last message I see
> from the kernel is:
> NET: Registered protocol family 2
>
> Compiling with debug allows me to single-step through the kernel. I've
> traced execution from inet_init(), to synchronize_net(), to
> synchronize_kernel(), to a call to wait_for_completion(), to
> switch_to_tt(), after which the kernel spends all its time in the idle
> loop. This happens whether I'm using SKAS or TT mode.
>
> Host kernel is 2.6.1 with Stephen William's 2.6.1 SKAS patch (thanks
> Stephen). Guest kernel is 2.6.1 with the latest patch from Sourceforge
> (January 15th), without modules, and with nearly everything disabled at
> compile except core functionality and IPv4.
>
> I've tried to find similar cases in the FAQ's and the list archives, but
> I'm not seeing anything. It seems like the kernel is waiting for an
> event related to IPv4 initialization that it never gets, but I'm not
> familiar enough with the kernel proper to know what that might be. Does
> anyone have any ideas?
>
> Thanks in advance.
>
> --
> Phil Nadeau
> Software Services Manager
> phil.nadeau@innercite.com
> (916)932-3200, (800)921-5513
>
>
>
> -------------------------------------------------------
> The SF.Net email is sponsored by EclipseCon 2004
> Premiere Conference on Open Tools Development and Integration
> See the breadth of Eclipse activity. February 3-5 in Anaheim, CA.
> http://www.eclipsecon.org/osdn
> _______________________________________________
> User-mode-linux-devel mailing list
> User-mode-linux-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
>


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Re: [uml-devel] Kernel idles in loop after loading IPv4

[Jeff Dike]

pyro@linuxlabs.com said:
> I ran into that as well, but didn't have time to do much about it. As
> a further datapoint, if I disable all net support and pass it init=/
> bin/bash, I get the bash prompt (ubd filesystems do get checked/
> mounted) but then it goes into the idle loop and stays there. 

Hmmm.

If you could get a stack trace from the last call to schedule, that would be
handy.  You could automate it with
	comm <n>
	bt
	c
	end

with breakpoint <n> attached to schedule().

				Jeff



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Re: [uml-devel] Kernel idles in loop after loading IPv4

[Phil Nadeau]

[-- Attachment #1: Type: text/plain, Size: 1346 bytes --]

On Tue, 2004-01-27 at 20:39, Jeff Dike wrote:
> If you could get a stack trace from the last call to schedule, that would be
> handy.  You could automate it with
> 	comm <n>
> 	bt
> 	c
> 	end
> 
> with breakpoint <n> attached to schedule().
> 
> 				Jeff

Here's the last part of a debug session that I ran which produced the
error. The full transcript is attached. Thanks in advance.

NET: Registered protocol family 2
  
Breakpoint 1, schedule () at kernel/sched.c:1489
1489            if (likely(!(current->state & (TASK_DEAD | TASK_ZOMBIE)))) {
#0  schedule () at kernel/sched.c:1489
#1  0xa002db4e in wait_for_completion (x=0xa1fefb64) at kernel/sched.c:1758
#2  0xa0041104 in synchronize_kernel () at kernel/rcupdate.c:262
#3  0xa000b5dc in inet_init () at net/ipv4/af_inet.c:1144
#4  0xa00024e8 in do_initcalls () at init/main.c:499
#5  0xa000c679 in init (unused=0x0) at init/main.c:581
#6  0xa00141d3 in run_kernel_thread (fn=0xa000c658 <init>, arg=0x0,
jmp_ptr=0xa08bfab4) at arch/um/kernel/process.c:241
#7  0xa001fe23 in new_thread_handler (sig=10) at
arch/um/kernel/skas/process_kern.c:71
#8  <signal handler called>
#9  0xa0155fed in syscall () at seq_file.h:49
Previous frame inner to this frame (corrupt stack?)
(gdb) c
Continuing.

-- 
Phil Nadeau
Software Services Manager
phil.nadeau@innercite.com
(916)932-3200, (800)921-5513

[-- Attachment #2: debug_session.gz --]
[-- Type: application/x-gzip, Size: 3416 bytes --]

Re: [uml-devel] Kernel idles in loop after loading IPv4

[BlaisorBlade]

Alle 22:23, venerdì 30 gennaio 2004, Phil Nadeau ha scritto:
> On Tue, 2004-01-27 at 20:39, Jeff Dike wrote:

> Here's the last part of a debug session that I ran which produced the
> error. The full transcript is attached. Thanks in advance.

Could you try to reproduce this bug running onto a 2.4 host-skas kernel with 
the same guest kernel? Most people have no problem with the code; also, the 
host-skas patch for 2.6 that you used has more than one bug (somebody even 
reported kernel Oopses with that applied). Also, I'd like more info on the 
host configuration: glibc/gcc version and distro used.

> NET: Registered protocol family 2
>
> Breakpoint 1, schedule () at kernel/sched.c:1489
> 1489            if (likely(!(current->state & (TASK_DEAD | TASK_ZOMBIE))))
> { #0  schedule () at kernel/sched.c:1489
> #1  0xa002db4e in wait_for_completion (x=0xa1fefb64) at kernel/sched.c:1758
> #2  0xa0041104 in synchronize_kernel () at kernel/rcupdate.c:262
> #3  0xa000b5dc in inet_init () at net/ipv4/af_inet.c:1144

An old message, "[uml-devel] wait queues broken?" on 19 November 2003, spoke 
of something that could be related to this. Since everything is about 
scheduling, this error message I got could be of interest:

Kernel panic: Kernel mode fault at addr 0x1f, ip 0x400d1397
Kernel panic: kernel BUG at kernel/exit.c:793!

The second message is of interest because the BUG line of interest reads as:
  schedule();
  BUG();
and this is fairly interesting.

To get this, I've run this command:

while /bin/true ; do /bin/true ; done

However, the kernel I was running went on after the "NET: Registered protocol 
family 2" message.
-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729




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Re: [uml-devel] Kernel idles in loop after loading IPv4

[Phil Nadeau]

On Sun, 2004-02-15 at 09:12, BlaisorBlade wrote:
> Alle 22:23, venerdì 30 gennaio 2004, Phil Nadeau ha scritto:
> > On Tue, 2004-01-27 at 20:39, Jeff Dike wrote:
> 
> > Here's the last part of a debug session that I ran which produced the
> > error. The full transcript is attached. Thanks in advance.
> 
> Could you try to reproduce this bug running onto a 2.4 host-skas kernel with 
> the same guest kernel? Most people have no problem with the code; also, the 
> host-skas patch for 2.6 that you used has more than one bug (somebody even 
> reported kernel Oopses with that applied). Also, I'd like more info on the 
> host configuration: glibc/gcc version and distro used.
> 

gcc (GCC) 3.3.2 20031022 (Red Hat Linux 3.3.2-1)
glibc-2.3.2
libpthread-0.10

Kernel is Linux version 2.6.1 (root@build1.innercite.com) (gcc version
3.3.2 20031022 (Red Hat Linux 3.3.2-1))

Based on other things I've seen on the list, I suspect it's an issue
with the host using NPTL. This occurs with 2.4.22 Fedora Core kernels
and vanilla 2.6.0 and 2.6.1 kernels compiled with and without SKAS.
Since NPTL seems to be a Known Issue, I was leaving it alone for now.
Any other ideas?

-- 
Phil Nadeau
Software Services Manager
phil.nadeau@innercite.com
(916)932-3200, (800)921-5513



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Re: [uml-devel] Kernel idles in loop after loading IPv4

[Christopher Olson]

I started from Fedora Core 1, which I upgraded to a
2.6.1 kernel the skas3.  I also suspected NPTL was
causing the troubles, so I tried moving /lib/tls to
/lib/tls.off and still got the hang.  I also tried
rebuilding glibc-2.3.2 with linux threads, then
building and running UML against that, but I still got
the hang.

I obtained the skas3 patch from sdw.st.  Alegedly, it
has problems, but it was the only skas3 patch I could
apply to 2.6.1 cleanly.

Chris.

--- Phil Nadeau <phil@innercite.com> wrote:

> Based on other things I've seen on the list, I
> suspect it's an issue
> with the host using NPTL. This occurs with 2.4.22
> Fedora Core kernels
> and vanilla 2.6.0 and 2.6.1 kernels compiled with
> and without SKAS.
> Since NPTL seems to be a Known Issue, I was leaving
> it alone for now.
> Any other ideas?





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Re: [uml-devel] Kernel idles in loop after loading IPv4

[roland]

hi !
i have the same problem. 
my uml is 2.6.3-rc2 with jeff`s latest uml patch.
host is 2.6.0-test11 with skas patch
with 2.6.0-test11 + uml patch i didn`t have such problem.
any hints?
 
regards
roland


----- Original Message ----- 
From: "Phil Nadeau" <phil@innercite.com>
To: <user-mode-linux-devel@lists.sourceforge.net>
Sent: Tuesday, January 27, 2004 9:54 PM
Subject: [uml-devel] Kernel idles in loop after loading IPv4


> Hello UML developers,
> 
> I'm trying to use UML to set up a simulator for a high-availability
> cluster. I encounter the following unexpected behavior -
> 
> On any kernel that I compile with IPv4 support, the kernel will stop
> intializing drivers after loading IPv4 support. The last message I see
> from the kernel is:
> NET: Registered protocol family 2
> 
> Compiling with debug allows me to single-step through the kernel. I've
> traced execution from inet_init(), to synchronize_net(), to
> synchronize_kernel(), to a call to wait_for_completion(), to
> switch_to_tt(), after which the kernel spends all its time in the idle
> loop. This happens whether I'm using SKAS or TT mode.
> 
> Host kernel is 2.6.1 with Stephen William's 2.6.1 SKAS patch (thanks
> Stephen). Guest kernel is 2.6.1 with the latest patch from Sourceforge
> (January 15th), without modules, and with nearly everything disabled at
> compile except core functionality and IPv4.
> 
> I've tried to find similar cases in the FAQ's and the list archives, but
> I'm not seeing anything. It seems like the kernel is waiting for an
> event related to IPv4 initialization that it never gets, but I'm not
> familiar enough with the kernel proper to know what that might be. Does
> anyone have any ideas?
> 
> Thanks in advance.
> 
> -- 
> Phil Nadeau
> Software Services Manager
> phil.nadeau@innercite.com
> (916)932-3200, (800)921-5513
> 
> 
> 
> -------------------------------------------------------
> The SF.Net email is sponsored by EclipseCon 2004
> Premiere Conference on Open Tools Development and Integration
> See the breadth of Eclipse activity. February 3-5 in Anaheim, CA.
> http://www.eclipsecon.org/osdn
> _______________________________________________
> User-mode-linux-devel mailing list
> User-mode-linux-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
> 


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