The NetBSD libc malloc implementation performs its own out-of-memory
check, presumably for performance reasons. The check makes a strong
assumption about the address space layout, which is that memory-
mapped pages are always located above the heap. However, this
assumption does not necessarily hold on MINIX3, thus resulting in
malloc reporting an out-of-memory condition without the system
actually being out of memory at all. Evidence suggests that in
particular dynamically linked (i.e., pkgsrc) binaries were affected
by this issue - most notably git.