5.2-current does not allow login and panics with modifiedmemory after free

Doug White dwhite at gumbysoft.com
Fri Apr 2 19:11:14 PST 2004

On Fri, 2 Apr 2004, Artem Koutchine wrote:

> Hello!
> I am trying to run 5.2-CURRENT (cvsupped and rebuild apr 1) on the following
> server:
> Supermicro DPE-G2 motherboard
> DUAL XEON 2.66Ghz (HT enabled)

ECC or non-ECC RAM?

> SATA drivers are joint into a single RAID5 array which is seens
> as twe0.
> 3dm is installed.

Hm, I haven't had 3dm working on my machines with -CURRENT, but maybe I'm
doing something wierd.

> The box ran half a day and a night just fine. After that it was shutdown
> correctly and after a couple of hours turned on.
> I have heared (leds do not work due to connector incompatibility with
> supermicro case) high hdd activity for some time, but all filesysrems
> were marked as clean. I tried to login but i could not because after i
> types 'root' at the login nothing happened at all. Just a blinking cursor.
> However, the box was not hanging - screensaver appeared after some
> time and i can type on tty and also swicth vttys and use scroll lock to
> scroll
> boot messages. 3DM did not respond via web. So, i waited 4 hours and
> rebooted.
> After reboot i can logon but after several requests  to RAID status via
> web (3dm) i got the following on the console:
> twe0: TWEIO_GET_PARAM failed for 0x402/0x3/16

Sounds like one of the disks flaked out ... if you reboot and check the
3ware BIOS, does it complain one of the disks has failed?

> Then after a minute or two the following happened:
> Memory modified after free 0x788f400(508) val=20202020 @ 0xe788f400

Thats an ominous value.  The usual overwrite value is 0xd0d0d0d0, but that
looks like it was shifted.

> panic: Most recently used by devbuf
> at line 128 in file /usr/src/sys/udm_dbg.c
> cpu=0;
> Debugger ("panic")
> Stopped at Debugger +0.46: xchgl %ebx, in_Debugger.0

I suspect this is a secondary issue with a drive problem.  We'd need a
backtrace to get more info, however. ('tr' at hte ddb prompt.)

Doug White                    |  FreeBSD: The Power to Serve
dwhite at gumbysoft.com          |  www.FreeBSD.org

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