mm/vmstat: refresh stats remotely instead of via work item

mm/vmstat: refresh stats remotely instead of via work item

Refresh per-CPU stats remotely, instead of queueing work items, for the
stat_refresh procfs method.

This fixes sosreport hang (which uses vmstat_refresh) with spinning
SCHED_FIFO process.

Link: https://lkml.kernel.org/r/20230320180745.832991792@redhat.com
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Aaron Tomlin <atomlin@atomlin.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>