[rt] mm/page_alloc.c: add remote version of new local_lock interface and enable remote draining

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1992951 Testing: tested by Pei (see BZ). Upstream status: RHEL-only

This patch (or equivalent version of it) is part of RHEL-7-RT and RHEL 8-RT.

Description:

What this patch does is to re-enable remote draining, by replacing the workqueue based per-cpu flushing with

    for_each_cpu(cpu, &cpus_with_pcps)
            drain_pages(cpu);

The local_lock interface in RHEL 9 is acquiring only the local CPU lock: provide a _on version which uses per_cpu_ptr(lock, cpu).

Signed-off-by: Marcelo Tosatti mtosatti@redhat.com