Interrupts, ATAng, and wayward pointers, oh my!

Ladies and Gents,

I have the following (hand transcript) panici during boot from
a kernel built from 1 hour old sources:

ad0: 38154MB <IC25N040ATC05-0> [77520/16/63] at ata0-master UDMA100 
ata1-slave: FAILURE - ATAPI_IDENTIFY no interrupt
ata1-slave: FAILURE - ATAPI_IDENTIFY no interrupt
acd0: DVDROM <HL-DT-STDVD-ROM GDR8081N> at ata1-master WDMA2
Mounting root from ufs:/dev/ad0s3a
Memory modified after free 0xc407a800(508) val=ff00ff00 _at_ 0xc407a800


Fatal trap 12: page fault while in kernel mode
fault virtual address   = 0xff00ff20
fault code              = supervisor read, page not present
instruction pointer     = 0x8:0xc05b945a
stack pointer           = 0x10:0xd84d1984
frame pointer           = 0x10:0xd84d19a0
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 49 (sh)
kernel: type 12 trap, code=0
stopped at    mtrash_ctor+0x3a:    movl  0x20(%eax),%eax
db> trace
mtrash_ctor(c407a800,200,0) at mtrash_ctor+0x3a
uma_zalloc_arg(c0c45cc0,0,2) at uma_zalloc_arg+0x169
malloc(188,c0650d00,2,3,c3fe27e0) at malloc+0xb7
elf32_load_file(c41c2528,d4cb20f4,d84d1ab0,d84d1bd0,1000) at elf32_load_file+0x51
exec_elf32_imgact(d84d1b94,c051fb78,c067d450,0,0) at exec_elf32_imgact+0x4c7
kern_execve(c3fe27e0,8065098,8065084,8065094,0) at kern_execve+0x33a
execve(c3fe27e0,d84d1d14,3,0,286) at execve+0x18
syscall(2f,2f,2f,8065098,8065084) at syscall+0x217
Xint0x80_syscall() at Xint80_syscall+0x1d
--- syscall (59, FreeBSD ELF32, execve), eip = 0x2811ca6f, esp=0xbfbfec8c, ebp = 0xbfbfecb8
db> 

I can't get a core dump.

-- 
Steve