mm: Don't scrub pages while holding heap lock in alloc_heap_pages()

mm: Don't scrub pages while holding heap lock in alloc_heap_pages()

Instead, preserve PGC_need_scrub bit when setting PGC_state_inuse
state while still under the lock and clear those pages later.

Note that we still need to grub the lock when clearing PGC_need_scrub
bit since count_info might be updated during MCE handling in
mark_page_offline().

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>