----- Original Message -----
From: "Martin Östlund" <mo@microsaft.nu>
To: <security-discuss@linuxsecurity.com>
Sent: Monday, January 13, 2003 9:22 AM
Subject: Unable to handle kernel paging
> Hello listpeople.
>
> Recently my server has been getting this in the syslog:
>
> Jan 9 00:30:38 lysithea kernel: Unable to handle kernel paging request at
virtual address c72674ca
> Jan 9 00:30:38 lysithea kernel: *pde = 00000000
>
> Then it becomes unavaible through ssh, telnet and ftp (proftpd).
>
> the www is avaible, and an ircbouncer.
>
> The server is an AMD-K6, 128Mb ram, 334Mb swap, running Slackware Linux
> 8.1 with 2.4.20 kernel. I upgraded to 2.4.20 about 1 - 1.5 month ago, and
> these problems have started the last 2 weeks. A reboot fixes it, then it
> happens again after 24-36 hours.
>
> Any ideas?
What kind of hard drive? If the hard drive is having a read error when
attempting to grab a chunk of virtual memory stored on the swap partition,
that is a critical error which will freeze any process or thread relying on
that chunk of memory. Your WWW server may be running just fine because it's
currently retained in RAM and not swapped out.
Download a hard drive utility from the hard drive manufacturer and boot to
an old DOS disk to run it.
You could alternately boot Linux to single user mode, unmount the swap
partition and try to run an extensive fsck check against it.
I would try this both now and right after the problem occurs.
You could also disable your swap partition (/etc/fstab) since you have a
fair amount of RAM just to prove if it's the hard drive or other problem. I
disagree with earlier posting that your RAM could be the problem. That would
show other critical errors that would be unrelated to virtual memory. While
waiting to see if a problem occurs, keep another machine telnetted into your
server running the "top" process so that you get a snapshot of the RAM and
process running just before the freeze occurs.
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