Memory mapped through kgsl_mmu_map_global() is supposed to have
the same gpu address in all pagetables. And the memdesc will
persist beyond the lifetime of any single pagetable.
Therefore, memdesc->gpuaddr should not be zeroed for these
memdescs.
Previously, memory objects assumed that they remained attached to a
process until they are destroyed. In the past this was mostly true,
but worked by luck because a process could technically map the memory
and then close the file descriptor which would eventually explode. Now we
do the process related cleanup (MMU unmap, fixup statistics) when the
object is released from the process so the process can go away without
affecting the other holders of the mem object refcount.
The tools that process cff dumps expect a linear
memory region, but the start address of that region can
be configured. As long as there is only a single
pagetable (so that there aren't duplicate virtual
addresses in the dump), dumps captured with the
mmu on are easier to deal with than reconfiguring
to turn the mmu off.
