This reverts commit a00ce85af2a1be494d3b0c9457e8e81cdcce2a89.

Commit a00ce85af2a1 ("mm: make alloc_demote_folio externally invokable
for migration") was made to let DAMOS_MIGRATE_{HOT,COLD} call the
function.  But a previous commit made DAMOS_MIGRATE_{HOT,COLD} call
alloc_migration_target() instead.  Hence there are no more callers of
the function outside of vmscan.c.  Revert the commit to make the
function static again.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/internal.h | 1 -
 mm/vmscan.c   | 3 ++-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index aedcf95737ed..746fa4187e9e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1227,7 +1227,6 @@ extern unsigned long  __must_check vm_mmap_pgoff(struct file *, unsigned long,
         unsigned long, unsigned long);
 
 extern void set_pageblock_order(void);
-struct folio *alloc_demote_folio(struct folio *src, unsigned long private);
 unsigned long reclaim_pages(struct list_head *folio_list);
 unsigned int reclaim_clean_pages_from_list(struct zone *zone,
 					    struct list_head *folio_list);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6bebc91cbf2f..620dce753b64 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1006,7 +1006,8 @@ static void folio_check_dirty_writeback(struct folio *folio,
 		mapping->a_ops->is_dirty_writeback(folio, dirty, writeback);
 }
 
-struct folio *alloc_demote_folio(struct folio *src, unsigned long private)
+static struct folio *alloc_demote_folio(struct folio *src,
+		unsigned long private)
 {
 	struct folio *dst;
 	nodemask_t *allowed_mask;
-- 
2.39.5