mm: generalize putback scan functions

This combines two similar functions move_active_pages_to_lru() and
putback_inactive_pages() into single move_pages_to_lru().  This remove
duplicate code and makes object file size smaller.

Before:
   text	   data	    bss	    dec	    hex	filename
  57082	   4732	    128	  61942	   f1f6	mm/vmscan.o
After:
   text	   data	    bss	    dec	    hex	filename
  55112	   4600	    128	  59840	   e9c0	mm/vmscan.o

Note, that now we are checking for !page_evictable() coming from
shrink_active_list(), which shouldn't change any behavior since that path
works with evictable pages only.

Link: http://lkml.kernel.org/r/155290129627.31489.8321971028677203248.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4c5f4b862420f3cac1966d0c2d240e3aa3a95ab1..40ff747e0b3339d37b9fd9156a1a1b0bc8b267c9 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1807,33 +1807,53 @@ static int too_many_isolated(struct pglist_data *pgdat, int file,
        return isolated > inactive;
 }
 
-static noinline_for_stack void
-putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list)
+/*
+ * This moves pages from @list to corresponding LRU list.
+ *
+ * We move them the other way if the page is referenced by one or more
+ * processes, from rmap.
+ *
+ * If the pages are mostly unmapped, the processing is fast and it is
+ * appropriate to hold zone_lru_lock across the whole operation.  But if
+ * the pages are mapped, the processing is slow (page_referenced()) so we
+ * should drop zone_lru_lock around each page.  It's impossible to balance
+ * this, so instead we remove the pages from the LRU while processing them.
+ * It is safe to rely on PG_active against the non-LRU pages in here because
+ * nobody will play with that bit on a non-LRU page.
+ *
+ * The downside is that we have to touch page->_refcount against each page.
+ * But we had to alter page->flags anyway.
+ *
+ * Returns the number of pages moved to the given lruvec.
+ */
+
+static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
+                                                    struct list_head *list)
 {
        struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+       int nr_pages, nr_moved = 0;
        LIST_HEAD(pages_to_free);
+       struct page *page;
+       enum lru_list lru;
 
-       /*
-        * Put back any unfreeable pages.
-        */
-       while (!list_empty(page_list)) {
-               struct page *page = lru_to_page(page_list);
-               int lru;
-
+       while (!list_empty(list)) {
+               page = lru_to_page(list);
                VM_BUG_ON_PAGE(PageLRU(page), page);
-               list_del(&page->lru);
                if (unlikely(!page_evictable(page))) {
+                       list_del(&page->lru);
                        spin_unlock_irq(&pgdat->lru_lock);
                        putback_lru_page(page);
                        spin_lock_irq(&pgdat->lru_lock);
                        continue;
                }
-
                lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
                SetPageLRU(page);
                lru = page_lru(page);
-               add_page_to_lru_list(page, lruvec, lru);
+
+               nr_pages = hpage_nr_pages(page);
+               update_lru_size(lruvec, lru, page_zonenum(page), nr_pages);
+               list_move(&page->lru, &lruvec->lists[lru]);
 
                if (put_page_testzero(page)) {
                        __ClearPageLRU(page);
@@ -1847,13 +1867,17 @@ putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list)
                                spin_lock_irq(&pgdat->lru_lock);
                        } else
                                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, page_list);
+       list_splice(&pages_to_free, list);
+
+       return nr_moved;
 }
 
 /*
@@ -1945,7 +1969,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
        reclaim_stat->recent_rotated[0] = stat.nr_activate[0];
        reclaim_stat->recent_rotated[1] = stat.nr_activate[1];
 
-       putback_inactive_pages(lruvec, &page_list);
+       move_pages_to_lru(lruvec, &page_list);
 
        __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
 
@@ -1982,72 +2006,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
        return nr_reclaimed;
 }
 
-/*
- * This moves pages from the active list to the inactive list.
- *
- * We move them the other way if the page is referenced by one or more
- * processes, from rmap.
- *
- * If the pages are mostly unmapped, the processing is fast and it is
- * appropriate to hold pgdat->lru_lock across the whole operation.  But if
- * the pages are mapped, the processing is slow (page_referenced()) so we
- * should drop pgdat->lru_lock around each page.  It's impossible to balance
- * this, so instead we remove the pages from the LRU while processing them.
- * It is safe to rely on PG_active against the non-LRU pages in here because
- * nobody will play with that bit on a non-LRU page.
- *
- * The downside is that we have to touch page->_refcount against each page.
- * But we had to alter page->flags anyway.
- *
- * Returns the number of pages moved to the given lru.
- */
-
-static unsigned move_active_pages_to_lru(struct lruvec *lruvec,
-                                    struct list_head *list,
-                                    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;
-
-       while (!list_empty(list)) {
-               page = lru_to_page(list);
-               lruvec = mem_cgroup_page_lruvec(page, pgdat);
-
-               VM_BUG_ON_PAGE(PageLRU(page), page);
-               SetPageLRU(page);
-
-               nr_pages = hpage_nr_pages(page);
-               update_lru_size(lruvec, lru, page_zonenum(page), nr_pages);
-               list_move(&page->lru, &lruvec->lists[lru]);
-
-               if (put_page_testzero(page)) {
-                       __ClearPageLRU(page);
-                       __ClearPageActive(page);
-                       del_page_from_lru_list(page, lruvec, lru);
-
-                       if (unlikely(PageCompound(page))) {
-                               spin_unlock_irq(&pgdat->lru_lock);
-                               mem_cgroup_uncharge(page);
-                               (*get_compound_page_dtor(page))(page);
-                               spin_lock_irq(&pgdat->lru_lock);
-                       } else
-                               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;
-}
-
 static void shrink_active_list(unsigned long nr_to_scan,
                               struct lruvec *lruvec,
                               struct scan_control *sc,
@@ -2134,8 +2092,8 @@ 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, lru);
-       nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, lru - LRU_ACTIVE);
+       nr_activate = move_pages_to_lru(lruvec, &l_active);
+       nr_deactivate = move_pages_to_lru(lruvec, &l_inactive);
        /* Keep all free pages in l_active list */
        list_splice(&l_inactive, &l_active);