memory tiering: count PGPROMOTE_SUCCESS when mem tiering is enabled.

JIRA: https://issues.redhat.com/browse/RHEL-84184
Conflicts:
  * context differences from upstream due to RHEL-9 missing commit
    7262f20 ("mm/migrate: split source folio if it is on
    deferred split list") and its follow-up fix commit 6e49019
    ("mm/migrate: putback split folios when numa hint migration fails"),
    with none of them being relevant to this backport

This patch is a backport of the following upstream commit:
commit ac59a1f
Author: Zi Yan <ziy@nvidia.com>
Date:   Wed Jul 24 09:01:15 2024 -0400

    memory tiering: count PGPROMOTE_SUCCESS when mem tiering is enabled.

    memory tiering can be enabled/disabled at runtime and
    sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING is used to
    check it.  In migrate_misplaced_folio(), the check is missing when
    PGPROMOTE_SUCCESS is incremented.  Add the missing check.

    Link: https://lkml.kernel.org/r/20240724130115.793641-4-ziy@nvidia.com
    Fixes: 3302453 ("memory tiering: hot page selection with hint page fault latency")
    Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
    Closes: https://lore.kernel.org/linux-mm/f4ae2c9c-fe40-4807-bdb2-64cf2d716c1a@huawei.com/
    Signed-off-by: Zi Yan <ziy@nvidia.com>
    Acked-by: David Hildenbrand <david@redhat.com>
    Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
    Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
    Cc: "Huang, Ying" <ying.huang@intel.com>
    Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Rafael Aquini <raquini@redhat.com>

Author: Rafael Aquini

mm/migrate.c

@@ -2600,7 +2600,9 @@ int migrate_misplaced_folio(struct folio *folio, struct vm_area_struct *vma,
 	}
 	if (nr_succeeded) {
 		count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
-		if (!node_is_toptier(folio_nid(folio)) && node_is_toptier(node))
+		if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
+		    && !node_is_toptier(folio_nid(folio))
+		    && node_is_toptier(node))
 			mod_node_page_state(pgdat, PGPROMOTE_SUCCESS,
 					    nr_succeeded);
 	}