Debugging kernel lockups during network activity

Debugging kernel lockups during network activity

[Art Haas]

Hi.

I've got Fedora Rawhide running on a SMP PIII machine, and the latest
kernels from Fedora have been locking up when I run 'yum update' to
get the latest packages. I also experience lock-ups when I use
Firefox to do some web browsing. Not all my network usage results in a
lockup, however. I can usually do 'git pull' and update git itself or
my copy of Linus' kernel tree without problems, as well as update my
GCC repo with subversion and Mozilla with cvs. I realize that running
Fedora Rawhide means when things break I can keep the pieces, so
the lockups or other occasional issues are not unexpected.

I'm writing to the 'netdev' list in an effort to get some pointers as to
how I can try and debug the problem. When I boot off my FC5 install
disk and run 'linux rescue' I can chroot to the system and update
the machine without problems, and I've also run memtest86 on it and
found no memory issues, so I'm certain the problem is in the Fedora
kernel. I don't know how to try and narrow down the problem to provide a
decent bug report, or if there is/are settings I can adjust which may
help to identify what is happening.

I'd mailed the fedora-test list and received no response, so I thought I
could try the main network development list. Are there a few tips,
tricks, or pointers that could be sent my way which others use to debug
networking problems like the one described above? Thanks in advance, and
my thanks to everyone working on the kernel.

Art Haas
-- 
Man once surrendering his reason, has no remaining guard against absurdities
the most monstrous, and like a ship without rudder, is the sport of every wind.

-Thomas Jefferson to James Smith, 1822

Re: Debugging kernel lockups during network activity

[Stephen Hemminger]

On Thu, 27 Jul 2006 13:19:43 -0500
"Art Haas" <ahaas@airmail.net> wrote:

> Hi.
> 
> I've got Fedora Rawhide running on a SMP PIII machine, and the latest
> kernels from Fedora have been locking up when I run 'yum update' to
> get the latest packages. I also experience lock-ups when I use
> Firefox to do some web browsing. Not all my network usage results in a
> lockup, however. I can usually do 'git pull' and update git itself or
> my copy of Linus' kernel tree without problems, as well as update my
> GCC repo with subversion and Mozilla with cvs. I realize that running
> Fedora Rawhide means when things break I can keep the pieces, so
> the lockups or other occasional issues are not unexpected.
> 
> I'm writing to the 'netdev' list in an effort to get some pointers as to
> how I can try and debug the problem. When I boot off my FC5 install
> disk and run 'linux rescue' I can chroot to the system and update
> the machine without problems, and I've also run memtest86 on it and
> found no memory issues, so I'm certain the problem is in the Fedora
> kernel. I don't know how to try and narrow down the problem to provide a
> decent bug report, or if there is/are settings I can adjust which may
> help to identify what is happening.
> 
> I'd mailed the fedora-test list and received no response, so I thought I
> could try the main network development list. Are there a few tips,
> tricks, or pointers that could be sent my way which others use to debug
> networking problems like the one described above? Thanks in advance, and
> my thanks to everyone working on the kernel.
> 
> Art Haas

Basic kernel debugging is good place to start.  If you can place a serial
console on the machine, and run commands from there. If that isn't possible
make sure and run from console virtual terminal (ie not X) so that if
there are kernel messages you can see them.  The debugging sysrq-p and
sysrq-t will show current state if machine isn't completely dead.

Re: Debugging kernel lockups during network activity

[Jarek Poplawski]

On 27-07-2006 20:19, Art Haas wrote:
> Hi.
> 
> I've got Fedora Rawhide running on a SMP PIII machine, and the latest
> kernels from Fedora have been locking up when I run 'yum update' to
> get the latest packages. I also experience lock-ups when I use
> Firefox to do some web browsing. Not all my network usage results in a
> lockup, however. I can usually do 'git pull' and update git itself or
> my copy of Linus' kernel tree without problems, as well as update my
> GCC repo with subversion and Mozilla with cvs. I realize that running
> Fedora Rawhide means when things break I can keep the pieces, so
> the lockups or other occasional issues are not unexpected.

I don't know the numbers of this kernels, but did you try 
linux-2.6.18-rc2.

It has some great patch to queue scheduler by Hubert Xu. I think 
it is some Gnu/miracle that it has been working (mostly) under 
heavy load without this patch.

But there are also other possibilities...

Jarek P.

Re: Debugging kernel lockups during network activity

[Jarek Poplawski]

On 28-07-2006 16:39, Jarek Poplawski wrote:
...

> It has some great patch to queue scheduler by Hubert Xu. I think it is 

I'm immensly sorry to change the name of Mr Herbert Xu.

And I thought it's easy name - just like some famous conductor 
(but not so famous). You'll not believe, but when I wrote this I 
checked mails not to misspell his surname!

Jarek P.