[PATCH 1/4] mm: Move recent_rotated pages calculation to shrink_inactive_list()

[Kirill Tkhai]

Currently, struct reclaim_stat::nr_activate is a local variable,
used only in shrink_page_list(). This patch introduces another
local variable pgactivate to use instead of it, and reuses
nr_activate to account number of active pages.

Note, that we need nr_activate to be an array, since type of page
may change during shrink_page_list() (see ClearPageSwapBacked()).

Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
---
 include/linux/vmstat.h |    2 +-
 mm/vmscan.c            |   15 +++++++--------
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 2db8d60981fe..bdeda4b079fe 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -26,7 +26,7 @@ struct reclaim_stat {
        unsigned nr_congested;
        unsigned nr_writeback;
        unsigned nr_immediate;
-       unsigned nr_activate;
+       unsigned nr_activate[2];
        unsigned nr_ref_keep;
        unsigned nr_unmap_fail;
 };
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ac4806f0f332..84542004a277 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1107,6 +1107,7 @@ static unsigned long shrink_page_list(struct list_head 
*page_list,
        LIST_HEAD(ret_pages);
        LIST_HEAD(free_pages);
        unsigned nr_reclaimed = 0;
+       unsigned pgactivate = 0;
 
        memset(stat, 0, sizeof(*stat));
        cond_resched();
@@ -1466,8 +1467,10 @@ static unsigned long shrink_page_list(struct list_head 
*page_list,
                        try_to_free_swap(page);
                VM_BUG_ON_PAGE(PageActive(page), page);
                if (!PageMlocked(page)) {
+                       int type = page_is_file_cache(page);
                        SetPageActive(page);
-                       stat->nr_activate++;
+                       pgactivate++;
+                       stat->nr_activate[type] += hpage_nr_pages(page);
                        count_memcg_page_event(page, PGACTIVATE);
                }
 keep_locked:
@@ -1482,7 +1485,7 @@ static unsigned long shrink_page_list(struct list_head 
*page_list,
        free_unref_page_list(&free_pages);
 
        list_splice(&ret_pages, page_list);
-       count_vm_events(PGACTIVATE, stat->nr_activate);
+       count_vm_events(PGACTIVATE, pgactivate);
 
        return nr_reclaimed;
 }
@@ -1807,7 +1810,6 @@ static int too_many_isolated(struct pglist_data *pgdat, 
int file,
 static noinline_for_stack void
 putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list)
 {
-       struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
        struct pglist_data *pgdat = lruvec_pgdat(lruvec);
        LIST_HEAD(pages_to_free);
 
@@ -1833,11 +1835,6 @@ putback_inactive_pages(struct lruvec *lruvec, struct 
list_head *page_list)
                lru = page_lru(page);
                add_page_to_lru_list(page, lruvec, lru);
 
-               if (is_active_lru(lru)) {
-                       int file = is_file_lru(lru);
-                       int numpages = hpage_nr_pages(page);
-                       reclaim_stat->recent_rotated[file] += numpages;
-               }
                if (put_page_testzero(page)) {
                        __ClearPageLRU(page);
                        __ClearPageActive(page);
@@ -1945,6 +1942,8 @@ shrink_inactive_list(unsigned long nr_to_scan, struct 
lruvec *lruvec,
                count_memcg_events(lruvec_memcg(lruvec), PGSTEAL_DIRECT,
                                   nr_reclaimed);
        }
+       reclaim_stat->recent_rotated[0] = stat.nr_activate[0];
+       reclaim_stat->recent_rotated[1] = stat.nr_activate[1];
 
        putback_inactive_pages(lruvec, &page_list);