mm/slab: pass alloc_flags to new slab allocation

mm/slab: pass alloc_flags to new slab allocation

Add the alloc_flags parameter to allocate_slab() and new_slab()
so it can be used to determine if spinning is allowed, independently
from gfp flags.

refill_objects() passes SLAB_ALLOC_DEFAULT because it can only be
reached from contexts that allow spinning.

Link: https://patch.msgid.link/20260610-slab_alloc_flags-v2-8-7190909db118@kernel.org
Reviewed-by: Hao Li <hao.li@linux.dev>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org>
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>