NFS swap on current appears to deadlock

[Paul Ripke <stix%stix.id.au@localhost>]

I have a qemu guest for experimenting with -current, 1 CPU & 64MiB RAM.
I gave it an NFS swap space to cope with a few small builds, and it now
locks up hard after touching that swap device.

From ddb, stacks are like:

db{0}> t
sched_resched_cpu() at netbsd:sched_resched_cpu+0x3f
sleepq_wake() at netbsd:sleepq_wake+0x6c
uvm_wait() at netbsd:uvm_wait+0x47
uvn_findpage() at netbsd:uvn_findpage+0x21b
uvn_findpages() at netbsd:uvn_findpages+0xca
genfs_getpages() at netbsd:genfs_getpages+0x107a
VOP_GETPAGES() at netbsd:VOP_GETPAGES+0x6b
uvm_fault_internal() at netbsd:uvm_fault_internal+0x1aae
trap() at netbsd:trap+0x521
--- trap (number 6) ---
c6c0bc1b:

db{0}> t
binuptime() at netbsd:binuptime+0x79
mi_switch() at netbsd:mi_switch+0x61
sleepq_block() at netbsd:sleepq_block+0xb4
mtsleep() at netbsd:mtsleep+0x137
uvm_pageout() at netbsd:uvm_pageout+0x69e

They seem to change around, but userland in the OS seems pretty
locked up. Running with the NFS swap space disabled, using a normal
swap partition, is fine.

This is 9.99.56 amd64, btw.

Ideas?

Cheers,
-- 
Paul Ripke
"Great minds discuss ideas, average minds discuss events, small minds
 discuss people."
-- Disputed: Often attributed to Eleanor Roosevelt. 1948.