Page fault in FreeBSD 5.3 on IBM e325, Dual AMD64 2.2GHz, 4GB

I had precisely this same problem over the weekend moving from FreeBSD  
5.3-RC1 to 5.3_RELENG.

Other symptoms: network stack problems at boot (ntpdate didn't work  
until after the system was fully up.)

Reverting to RC1 seems to have solved the problem.

On Mon, 22 Nov 2004, Ganbold wrote:

 > Fatal trap 12: page fault while in kernel mode
 > cpuid = 1; apic id = 01
 > fault virtual address = 0x18
 > fault code            = supervisor read, page not present
 > instruction pointer   = 0x8:0xffffffff80277fc0
 > stack pointer         = 0x10:0xffffffffb36ab830
 > frame pointer         = 0x10:0xffffffffb36ab890
 > code segment          = base 0x0, limit 0xfffff, type 0x1b
 >                       = DPL 0, pres 1, long 1, def32 0, gran 1
 > processor eflags      = interrupt enabled, resume, IOPL = 0
 > current process               = 44 (swi1: net)
 > [thread 100044]
 > Stopped at      m_copym+0x190:  incl    %ecx
<...>
 >  
------------------------------------------------------------------------ 
--------------------------------
 >
 > It seems to me the problem is related to network stack and threading.
 > Am I right? How to solve this problem?

I've seen reports of this problem with and without debug.mpsafenet=1,
which suggests it is a network stack bug but not specific to locking.  
I've
also seen reports that disabling TCP SACK will make the problem go away,
which would be good to confirm.  I spent the weekend building up some  
more
expertise in TCP and reading a lot of TCP code, and hope to look at this
problem in more detail today.  You may want to try turning off TCP sack
using net.inet.tcp.sack.enable=0 in sysctl.conf (or loader.conf).

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert at fledge.watson.org      Principal Research Scientist, McAfee  
Research