bus_dmamap_destroy no longer callable from interrupt context?

[Christoph Badura <bad%bsd.de@localhost>]

While trying to port BCM586x support I discovered that I get the following
panic under -current.  The same code works fine on -6.  What gives?

panic: kernel diagnostic assertion "((!cpu_intr_p() && !cpu_softintr_p()) || 
(pc->pc_pool.pr_ipl != IPL_NONE || cold || panicstr != NULL)" failed: file 
"../../../../kern/subr_pool.c", line 2209 pool 'vmmpepl' is IPL_NONE, but 
called from interrupt context

backtrace:
...
kern_assert
pool_cache_get_paddr
_uvm_mapent_alloc.clone.2
uvm_map_dup_start
uvm_unmap_remove
uvm_unmap1
_bus_dmamap_destroy_clone.8
ubsec_callback+0x9d
ubsec_intr+0x100
intr_biglock_wrapper
...

This is generic ubsec code that is used by our currently supported devices.
I.e. ubsec(4) should be completely busted.

--chris