mm, slub: move reset of c->page and freelist out of deactivate_slab()

mm, slub: move reset of c->page and freelist out of deactivate_slab()

deactivate_slab() removes the cpu slab by merging the cpu freelist with
slab's freelist and putting the slab on the proper node's list.  It also
sets the respective kmem_cache_cpu pointers to NULL.

By extracting the kmem_cache_cpu operations from the function, we can make
it not dependent on disabled irqs.

Also if we return a single free pointer from ___slab_alloc, we no longer
have to assign kmem_cache_cpu.page before deactivation or care if somebody
preempted us and assigned a different page to our kmem_cache_cpu in the
process.

Link: https://lkml.kernel.org/r/20210805152000.12817-20-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>