[PATCH 3/4] mm: Remove pages_to_free argument of move_active_pages_to_lru()

[Kirill Tkhai]

We may use input argument list as output argument too.
This makes the function more similar to putback_inactive_pages().

Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
---
 mm/vmscan.c |   19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8d7d55e71511..88fa71e4c28f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2004,10 +2004,10 @@ shrink_inactive_list(unsigned long nr_to_scan, struct 
lruvec *lruvec,
 
 static unsigned move_active_pages_to_lru(struct lruvec *lruvec,
                                     struct list_head *list,
-                                    struct list_head *pages_to_free,
                                     enum lru_list lru)
 {
        struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+       LIST_HEAD(pages_to_free);
        struct page *page;
        int nr_pages;
        int nr_moved = 0;
@@ -2034,12 +2034,17 @@ static unsigned move_active_pages_to_lru(struct lruvec 
*lruvec,
                                (*get_compound_page_dtor(page))(page);
                                spin_lock_irq(&pgdat->lru_lock);
                        } else
-                               list_add(&page->lru, pages_to_free);
+                               list_add(&page->lru, &pages_to_free);
                } else {
                        nr_moved += nr_pages;
                }
        }
 
+       /*
+        * To save our caller's stack, now use input list for pages to free.
+        */
+       list_splice(&pages_to_free, list);
+
        return nr_moved;
 }
 
@@ -2129,8 +2134,10 @@ static void shrink_active_list(unsigned long nr_to_scan,
         */
        reclaim_stat->recent_rotated[file] += nr_rotated;
 
-       nr_activate = move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru);
-       nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, 
lru - LRU_ACTIVE);
+       nr_activate = move_active_pages_to_lru(lruvec, &l_active, lru);
+       nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, lru - 
LRU_ACTIVE);
+       /* Keep all free pages are in l_active list */
+       list_splice(&l_inactive, &l_active);
 
        __count_vm_events(PGDEACTIVATE, nr_deactivate);
        __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate);
@@ -2138,8 +2145,8 @@ static void shrink_active_list(unsigned long nr_to_scan,
        __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
        spin_unlock_irq(&pgdat->lru_lock);
 
-       mem_cgroup_uncharge_list(&l_hold);
-       free_unref_page_list(&l_hold);
+       mem_cgroup_uncharge_list(&l_active);
+       free_unref_page_list(&l_active);
        trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate,
                        nr_deactivate, nr_rotated, sc->priority, file);
 }