mm,page_owner: filter out stacks by a threshold

We want to be able to filter out the stacks based on a threshold we can
can tune.  By writing to 'count_threshold' file, we can adjust the
threshold value.

Link: https://lkml.kernel.org/r/20240215215907.20121-7-osalvador@suse.de


Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>