mm, slub: fix memory and cpu hotplug related lock ordering issues

mm, slub: fix memory and cpu hotplug related lock ordering issues

Qian Cai reported [1] a lockdep splat on memory offline.

[   91.374541] WARNING: possible circular locking dependency detected
[   91.381411] 5.14.0-rc5-next-20210809+ #84 Not tainted
[   91.387149] ------------------------------------------------------
[   91.394016] lsbug/1523 is trying to acquire lock:
[   91.399406] ffff800018e76530 (flush_lock){+.+.}-{3:3}, at: flush_all+0x50/0x1c8
[   91.407425] but task is already holding lock:
[   91.414638] ffff800018e48468 (slab_mutex){+.+.}-{3:3}, at: slab_memory_callback+0x44/0x280
[   91.423603] which lock already depends on the new lock.

To fix it, we need to change the order in flush_all() so that
cpus_read_lock() is first and mutex_lock(&flush_lock) second.

Also when called from slab_mem_going_offline_callback() we are already
under cpus_read_lock() and cannot take it again, so create a
flush_all_cpus_locked() variant and decouple flushing from actual
shrinking for this call path.

Additionally, Mike Galbraith reported [2] wrong order of cpus_read_lock()
and slab_mutex in kmem_cache_destroy() path and proposed a fix to reverse
it.

This patch is a fixup for the mmotm patch
mm-slub-move-flush_cpu_slab-invocations-__free_slab-invocations-out-of-irq-context.patch

[1] https://lore.kernel.org/lkml/0b36128c-3e12-77df-85fe-a153a714569b@quicinc.com/
[2] https://lore.kernel.org/lkml/2eb3cf340716c40f03a0a342ab40219b3d1de195.camel@gmx.de/

Link: https://lkml.kernel.org/r/50fe26ba-450b-af57-506d-438f67cfbce3@suse.cz
Reported-by: Qian Cai <quic_qiancai@quicinc.com>
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>