mm: rearrange putback_inactive_pages

There is sometimes confusion between the global putback_lru_pages() in
migrate.c and the static putback_lru_pages() in vmscan.c: rename the
latter putback_inactive_pages(): it helps shrink_inactive_list() rather as
move_active_pages_to_lru() helps shrink_active_list().

Remove unused scan_control arg from putback_inactive_pages() and from
update_isolated_counts().  Move clear_active_flags() inside
update_isolated_counts().  Move NR_ISOLATED accounting up into
shrink_inactive_list() itself, so the balance is clearer.

Do the spin_lock_irq() before calling putback_inactive_pages() and
spin_unlock_irq() after return from it, so that it better matches
update_isolated_counts() and move_active_pages_to_lru().

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 44 insertions, 52 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9aab5dc51718..2880396f7953 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1284,32 +1284,6 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
         return nr_taken;
 }
 
-/*
- * clear_active_flags() is a helper for shrink_active_list(), clearing
- * any active bits from the pages in the list.
- */
-static unsigned long clear_active_flags(struct list_head *page_list,
-                                        unsigned int *count)
-{
-        int nr_active = 0;
-        int lru;
-        struct page *page;
-
-        list_for_each_entry(page, page_list, lru) {
-                int numpages = hpage_nr_pages(page);
-                lru = page_lru_base_type(page);
-                if (PageActive(page)) {
-                        lru += LRU_ACTIVE;
-                        ClearPageActive(page);
-                        nr_active += numpages;
-                }
-                if (count)
-                        count[lru] += numpages;
-        }
-
-        return nr_active;
-}
-
 /**
  * isolate_lru_page - tries to isolate a page from its LRU list
  * @page: page to isolate from its LRU list
@@ -1383,26 +1357,21 @@ static int too_many_isolated(struct zone *zone, int file,
         return isolated > inactive;
 }
 
-/*
- * TODO: Try merging with migrations version of putback_lru_pages
- */
 static noinline_for_stack void
-putback_lru_pages(struct mem_cgroup_zone *mz, struct scan_control *sc,
-                  unsigned long nr_anon, unsigned long nr_file,
-                  struct list_head *page_list)
+putback_inactive_pages(struct mem_cgroup_zone *mz,
+                       struct list_head *page_list)
 {
-        struct page *page;
-        LIST_HEAD(pages_to_free);
-        struct zone *zone = mz->zone;
         struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz);
+        struct zone *zone = mz->zone;
+        LIST_HEAD(pages_to_free);
 
         /*
          * Put back any unfreeable pages.
          */
-        spin_lock(&zone->lru_lock);
         while (!list_empty(page_list)) {
+                struct page *page = lru_to_page(page_list);
                 int lru;
-                page = lru_to_page(page_list);
+
                 VM_BUG_ON(PageLRU(page));
                 list_del(&page->lru);
                 if (unlikely(!page_evictable(page, NULL))) {
@@ -1432,26 +1401,40 @@ putback_lru_pages(struct mem_cgroup_zone *mz, struct scan_control *sc,
                                 list_add(&page->lru, &pages_to_free);
                 }
         }
-        __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
-        __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
 
-        spin_unlock_irq(&zone->lru_lock);
-        free_hot_cold_page_list(&pages_to_free, 1);
+        /*
+         * To save our caller's stack, now use input list for pages to free.
+         */
+        list_splice(&pages_to_free, page_list);
 }
 
 static noinline_for_stack void
 update_isolated_counts(struct mem_cgroup_zone *mz,
-                       struct scan_control *sc,
+                       struct list_head *page_list,
                        unsigned long *nr_anon,
-                       unsigned long *nr_file,
-                       struct list_head *isolated_list)
+                       unsigned long *nr_file)
 {
-        unsigned long nr_active;
+        struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz);
         struct zone *zone = mz->zone;
         unsigned int count[NR_LRU_LISTS] = { 0, };
-        struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz);
+        unsigned long nr_active = 0;
+        struct page *page;
+        int lru;
+
+        /*
+         * Count pages and clear active flags
+         */
+        list_for_each_entry(page, page_list, lru) {
+                int numpages = hpage_nr_pages(page);
+                lru = page_lru_base_type(page);
+                if (PageActive(page)) {
+                        lru += LRU_ACTIVE;
+                        ClearPageActive(page);
+                        nr_active += numpages;
+                }
+                count[lru] += numpages;
+        }
 
-        nr_active = clear_active_flags(isolated_list, count);
         __count_vm_events(PGDEACTIVATE, nr_active);
 
         __mod_zone_page_state(zone, NR_ACTIVE_FILE,
@@ -1465,8 +1448,6 @@ update_isolated_counts(struct mem_cgroup_zone *mz,
 
         *nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
         *nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
-        __mod_zone_page_state(zone, NR_ISOLATED_ANON, *nr_anon);
-        __mod_zone_page_state(zone, NR_ISOLATED_FILE, *nr_file);
 
         reclaim_stat->recent_scanned[0] += *nr_anon;
         reclaim_stat->recent_scanned[1] += *nr_file;
@@ -1571,7 +1552,10 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
                 return 0;
         }
 
-        update_isolated_counts(mz, sc, &nr_anon, &nr_file, &page_list);
+        update_isolated_counts(mz, &page_list, &nr_anon, &nr_file);
+
+        __mod_zone_page_state(zone, NR_ISOLATED_ANON, nr_anon);
+        __mod_zone_page_state(zone, NR_ISOLATED_FILE, nr_file);
 
         spin_unlock_irq(&zone->lru_lock);
 
@@ -1585,12 +1569,20 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
                                         priority, &nr_dirty, &nr_writeback);
         }
 
-        local_irq_disable();
+        spin_lock_irq(&zone->lru_lock);
+
         if (current_is_kswapd())
                 __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
         __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
 
-        putback_lru_pages(mz, sc, nr_anon, nr_file, &page_list);
+        putback_inactive_pages(mz, &page_list);
+
+        __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
+        __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
+
+        spin_unlock_irq(&zone->lru_lock);
+
+        free_hot_cold_page_list(&page_list, 1);
 
         /*
          * If reclaim is isolating dirty pages under writeback, it implies