hi,

> >however, i concluded that it didn't work.  
> >a split can occur even if you didn't merge entries
> >(eg. when you map [0..100] and then unmap [10..90].
> >of course, one doing such a thing can't assume unmap won't block.)
> >and it can consume "reserved" entries for merged maps which are
> >expected to be unmapped without blocking.
> 
> if the problem was uvm_unmap() sleeping when unmapping something
> because it needed to allocate a new vm_map_entry in order to perform a
> split, your example above demonstrates that disabling merging cannot
> solve the problem because merging could not have led to your
> configuration above in the first place.

sorry, i can't understand what you're saying.
what's "your configuration above"?  unmapping middle of a map? 
if so, i meant it's a bug of caller if it assumes it won't sleep.

YAMAMOTO Takashi