panic: UMA: page_free used with invalid flags 4

[Tim Chen]

Hello,
My server was using FreeBSD-7-Stable and performing
a mail server. Software I used is postfix 2.6.3
and dovecot 1.2.4.

The hardware is IBM blade server HS-21
CPU: dual Intel E5335 @ 2.00GHz
MEM: 3G
HD: onboard LSI RAID controller with 2 73G SAS HD.
(mpt0: <LSILogic SAS/SATA Adapter>)
The system is very stable until last week. After
csup the FreeBSD-7-STABLE source to around 2009/09/10,
it will halt randomly around every several hours. The
error message I saw  on console was the following:

panic: UMA: page_free used with invalid flags 4
cpuid = 0
Uptime: 3h1m14s
Physical memory: 3064MB
Dumping 1544MB: 1529 1513 1497....................

Reading freebsd-stable mailing shows there is some
vm related modfication during the first week of Sep.
(the panic: vm_phys_paddr_to_vm_page: paddr 0x series)
So, I csup my src back to 2009/09/01, the problem
disappeared, and system comes back with stable state.

Today, I csup my src to latest 7-STABLE (2009/09/15)
and problem comes again. It seems the problem is still
there and not be solved yet.

Would you please help to fix it?

Thanks very much.

Sincerely,
Tim Chen