kern/41974: panic in cpu_in_cksum / likely NFS issue

[spz%NetBSD.org@localhost]

>Number:         41974
>Category:       kern
>Synopsis:       panic in cpu_in_cksum
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Sep 02 06:00:00 +0000 2009
>Originator:     S.P.Zeidler
>Release:        NetBSD 5.0_STABLE
>Organization:
        TNF
>Environment:
System: NetBSD b2.netbsd.org 5.0_STABLE NetBSD 5.0_STABLE (BUILD) #5: Sun Aug 9 
20:35:32 UTC 2009 
tls@ADMIN:/chroots/netbsd-5/src/sys/arch/amd64/compile/obj/BUILD amd64
Architecture: x86_64
Machine: amd64
>Description:
        This has been greeting me at least 4 times now:

uvm_fault(0xffffffff80b662c0, 0xffff80012da62000, 1) -> e
fatal page fault in supervisor mode
trap type 6 code 0 rip ffffffff80465425 cs 8 rflags 10206 cr2  ffff80012da62000 
cpl 4 rsp ffff80003232c2b8
kernel: page fault trap, code=0
Stopped in pid 0.47 (system) at netbsd:cpu_in_cksum+0xa5:       movl    0(%rbx),
%ecx
db{0}> bt
cpu_in_cksum() at netbsd:cpu_in_cksum+0xa5
uvm_fault(0xffffffff80b87e60, 0x0, 1) -> e
fatal page fault in supervisor mode
trap type 6 code 0 rip ffffffff80466f54 cs 8 rflags 10246 cr2  53c cpl 8 rsp 
ffff80003232bc60
kernel: page fault trap, code=0
Faulted in DDB; continuing...
db{0}> sh reg
ds          0xd000
es          0x7008
fs          0xd000
gs          0x7a00
rdi         0xffff800009f4a400
rsi         0
rbp         0x534
rbx         0xffff80012da62000
rdx         0
rcx         0x800000
rax         0
r8          0x5010c889d
r9          0
r10         0
r11         0x5c8
r12         0x14
r13         0xffff800007cdd000
r14         0x2
r15         0xffff80003232c340
rip         0xffffffff80465425  cpu_in_cksum+0xa5
cs          0x8
rflags      0x10206
rsp         0xffff80003232c2b8
ss          0x10
netbsd:cpu_in_cksum+0xa5:       movl    0(%rbx),%ecx
db{0}> mach cpu
addr            dev     id      flags   ipis    curlwp          fpcurlwp
0xffffffff80ad0a00      cpu0    0       3009    0       0xffff80003231f7c0      
       0x0
0xffff800007bd1000      cpu1    1       f002    0       0xffff80003231f3e0      
0xffff8000323767e0
db{0}> mach cpu 1
using CPU 1
db{0}> bt
x86_pause() at netbsd:x86_pause
_kernel_lock() at netbsd:_kernel_lock+0xc7
sleepq_block() at netbsd:sleepq_block+0x1b3
cv_timedwait() at netbsd:cv_timedwait+0xb0
nfs_rcvlock() at netbsd:nfs_rcvlock+0xa2
nfs_request() at netbsd:nfs_request+0x421
nfs_writerpc() at netbsd:nfs_writerpc+0x42e
nfs_doio() at netbsd:nfs_doio+0x4d4
nfssvc_iod() at netbsd:nfssvc_iod+0x193
db{0}> sh reg
ds          0
es          0
fs          0
gs          0
rdi         0
rsi         0xffff800007bd1000
rbp         0xffff80003232f740
rbx         0
rdx         0x6
rcx         0
rax         0
r8          0
r9          0x60
r10         0xffff800007bd1080
r11         0
r12         0xffff800007bd1000
r13         0x1
r14         0xffff80003231f3e0
r15         0
rip         0xffffffff80465758  x86_pause
cs          0x8
rflags      0x246
rsp         0xffff80003232f6f8
ss          0x10
netbsd:x86_pause:       repe nop

        dumping won't work, alas. Any other info to grab next time?

>How-To-Repeat:
        run builds and wait
>Fix: