mm, slub: move disabling irqs closer to get_partial() in ___slab_alloc()

mm, slub: move disabling irqs closer to get_partial() in ___slab_alloc()

Continue reducing the irq disabled scope.  Check for per-cpu partial slabs
with first with irqs enabled and then recheck with irqs disabled before
grabbing the slab page.  Mostly preparatory for the following patches.

Link: https://lkml.kernel.org/r/20210805152000.12817-15-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>