panic with out of memory

Hi,

I just got a panic out of my r237195 system. The panic looks like:

Sleeping thread (tid 173153, pid 42034) owns a non-sleepable lock
KDB: stack backtrace of thread 173153:
sched_switch() at sched_switch+0x28a
mi_switch() at mi_switch+0xdf
sleepq_timedwait() at sleepq_timedwait+0x3a
_sleep() at _sleep+0x266
swp_pager_meta_build() at swp_pager_meta_build+0x259
swap_pager_copy() at swap_pager_copy+0x17b
vm_object_collapse() at vm_object_collapse+0x123
vm_object_deallocate() at vm_object_deallocate+0x457
vm_map_process_deferred() at vm_map_process_deferred+0x72
vm_pageout_oom() at vm_pageout_oom+0x180
swp_pager_meta_build() at swp_pager_meta_build+0x248
swap_pager_copy() at swap_pager_copy+0x17b
vm_object_collapse() at vm_object_collapse+0x123
vm_object_deallocate() at vm_object_deallocate+0x457
vm_map_process_deferred() at vm_map_process_deferred+0x72
vm_map_remove() at vm_map_remove+0x116
exec_new_vmspace() at exec_new_vmspace+0x1bc
exec_elf64_imgact() at exec_elf64_imgact+0x5f4
kern_execve() at kern_execve+0x6f0
sys_execve() at sys_execve+0x37
amd64_syscall() at amd64_syscall+0x351
Xfast_syscall() at Xfast_syscall+0xfb
--- syscall (59, FreeBSD ELF64, sys_execve), rip = 0x800d2eddc, rsp =
0x7fffffffd328, rbp = 0x7fffffffd470 ---
panic: sleeping thread
cpuid = 4

The system was very busy and using lots of swap, but I didn't expect a
panic. If any more detail is needed or I should just get more RAM, let
me know. :)

Thanks,
Steve