mm/hugetlb.c: don't zero 1GiB bootmem pages

mm/hugetlb.c: don't zero 1GiB bootmem pages

When using 1GiB pages during early boot, use the new
memblock_virt_alloc_try_nid_raw() to allocate memory without zeroing it.
Zeroing out hundreds or thousands of GiB in a single core memset() call
is very slow, and can make early boot last upwards of 20-30 minutes on
multi TiB machines.

The memory does not need to be zero'd as the hugetlb pages are always
zero'd on page fault.

Tested: Booted with ~3800 1G pages, and it booted successfully in
roughly the same amount of time as with 0, as opposed to the 25+ minutes
it would take before.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Cannon Matthews <[email protected]>
Acked-by: Mike Kravetz <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Andres Lagar-Cavilla <[email protected]>
Cc: Peter Feiner <[email protected]>
Cc: David Matlack <[email protected]>
Cc: Greg Thelen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>