KDASSERT(parent->gap == uvm_rb_gap(parent))

Hi all,

I've been able tonight to finally catch a crash I've been having for a
few weeks while playing videos with mplayer. It happens with a
-current kernel from end of April. The issue triggered  is a
KDASSERT() in uvm_map.c:

uvm_rb_fixup():
406: KDASSERT(parent->gap == uvm_rb_gap(parent));

This crash happens when mplayer ends playing a video. The backtrace is roughly

uvm_rb_fixup()
uvm_unmap_remove()
uvm_unmap1()
exit1()

This crash is not easily reproducible. I tried to trigger it for 30min
yesterday without success, got it 4 times in a row today in a 30min
interval (including reboot/fsck time) and nothing since.

Any ideas ?

Thanks,
 - Arnaud