Hangs up during reboot/shutdown

[Rick Stevens]

Tapas Ranjan wrote:
> Hi :
> 	Sometimes the pc hangs up during reboot. When the network is poor,
> the eth1 seems to be freezed and even typing "ifconfig" also hangs up.

That's not normal at all.  "ifconfig" should never hang the system
unless it's actually running something that's sucking down the CPU.
Before you do "ifconfig" try "ps -ax" or "top" and see how busy the CPU
is.

 >                                                                    So
> rebooting the system due to those problem hangs up the system  at 
> "shutting down loopback interfaces" or at "iptables".

The loopback interface is "lo" and is a purely software construct.
There is no hardware involved in that at all.  Shutting it down should
NEVER hang the system.

>                                                   This happens once in 
> 6-7 reboots or so.

I really suspect you have a runaway process.  "top" or "ps -ax" or
"uptime" should give you some clues

>  	I am using FC2 with 2.6.8-1.521 ( upgraded from 2.6.5-1.358
> through "yum" ). Help from experts is needed. 

I use that kernel all the time with no issues at all.

As near as I can tell, you have several possible issues:

	1. A runaway process
	2. Your machine has been hacked and is doing evil things
	3. Faulty hardware or memory

The "ps -ax" and "top" commands will show you what's running on your
machine (unless you've been had a rootkit hack), so that's the first
thing to check.  You should also try to run "chkrootkit" (do a google
search for it, then download and run it) to check for a rootkit hack.

You can test your memory by booting off FC2's first CD and entering
"memcheck86" at the "boot:" prompt.  If it shows bad memory, shut the
machine down, open it up and reseat ALL of your cards (memory, PCI
cards, and the CPU if possible).  You'd be amazed at how many "cranky"
machines get fixed just by reseating the cards.  Run the memtest86 again
and see if the problem has gone away.  If so, voila!  If not, then
you probably do have bad RAM.  And remember, Linux flogs your RAM a lot
harder than Windows does.  I've seen many systems with bad RAM run
Windows but not Linux.
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- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-  Memory is the second thing to go, but I can't remember the first! -
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