1 files changed, 77 insertions, 66 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index d196f46c8808..b07c48b09a93 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -52,6 +52,9 @@ struct scan_control {
         /* Incremented by the number of inactive pages that were scanned */
         unsigned long nr_scanned;
 
+        /* Number of pages freed so far during a call to shrink_zones() */
+        unsigned long nr_reclaimed;
+
         /* This context's GFP mask */
         gfp_t gfp_mask;
 
@@ -617,7 +620,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                                         referenced && page_mapping_inuse(page))
                         goto activate_locked;
 
-#ifdef CONFIG_SWAP
                 /*
                  * Anonymous process memory has backing store?
                  * Try to allocate it some swap space here.
@@ -625,20 +627,10 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                 if (PageAnon(page) && !PageSwapCache(page)) {
                         if (!(sc->gfp_mask & __GFP_IO))
                                 goto keep_locked;
-                        switch (try_to_munlock(page)) {
-                        case SWAP_FAIL:         /* shouldn't happen */
-                        case SWAP_AGAIN:
-                                goto keep_locked;
-                        case SWAP_MLOCK:
-                                goto cull_mlocked;
-                        case SWAP_SUCCESS:
-                                ; /* fall thru'; add to swap cache */
-                        }
-                        if (!add_to_swap(page, GFP_ATOMIC))
+                        if (!add_to_swap(page))
                                 goto activate_locked;
                         may_enter_fs = 1;
                 }
-#endif /* CONFIG_SWAP */
 
                 mapping = page_mapping(page);
 
@@ -752,6 +744,8 @@ free_it:
                 continue;
 
 cull_mlocked:
+                if (PageSwapCache(page))
+                        try_to_free_swap(page);
                 unlock_page(page);
                 putback_lru_page(page);
                 continue;
@@ -759,7 +753,7 @@ cull_mlocked:
 activate_locked:
                 /* Not a candidate for swapping, so reclaim swap space. */
                 if (PageSwapCache(page) && vm_swap_full())
-                        remove_exclusive_swap_page_ref(page);
+                        try_to_free_swap(page);
                 VM_BUG_ON(PageActive(page));
                 SetPageActive(page);
                 pgactivate++;
@@ -1173,11 +1167,6 @@ static inline void note_zone_scanning_priority(struct zone *zone, int priority)
                 zone->prev_priority = priority;
 }
 
-static inline int zone_is_near_oom(struct zone *zone)
-{
-        return zone->pages_scanned >= (zone_lru_pages(zone) * 3);
-}
-
 /*
  * This moves pages from the active list to the inactive list.
  *
@@ -1248,6 +1237,13 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
                 list_add(&page->lru, &l_inactive);
         }
 
+        /*
+         * Move the pages to the [file or anon] inactive list.
+         */
+        pagevec_init(&pvec, 1);
+        pgmoved = 0;
+        lru = LRU_BASE + file * LRU_FILE;
+
         spin_lock_irq(&zone->lru_lock);
         /*
          * Count referenced pages from currently used mappings as
@@ -1255,15 +1251,9 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
          * This helps balance scan pressure between file and anonymous
          * pages in get_scan_ratio.
          */
-        zone->recent_rotated[!!file] += pgmoved;
-
-        /*
-         * Move the pages to the [file or anon] inactive list.
-         */
-        pagevec_init(&pvec, 1);
+        if (scan_global_lru(sc))
+                zone->recent_rotated[!!file] += pgmoved;
 
-        pgmoved = 0;
-        lru = LRU_BASE + file * LRU_FILE;
         while (!list_empty(&l_inactive)) {
                 page = lru_to_page(&l_inactive);
                 prefetchw_prev_lru_page(page, &l_inactive, flags);
@@ -1336,12 +1326,6 @@ static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
         unsigned long anon_prio, file_prio;
         unsigned long ap, fp;
 
-        anon  = zone_page_state(zone, NR_ACTIVE_ANON) +
-                zone_page_state(zone, NR_INACTIVE_ANON);
-        file  = zone_page_state(zone, NR_ACTIVE_FILE) +
-                zone_page_state(zone, NR_INACTIVE_FILE);
-        free  = zone_page_state(zone, NR_FREE_PAGES);
-
         /* If we have no swap space, do not bother scanning anon pages. */
         if (nr_swap_pages <= 0) {
                 percent[0] = 0;
@@ -1349,6 +1333,12 @@ static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
                 return;
         }
 
+        anon  = zone_page_state(zone, NR_ACTIVE_ANON) +
+                zone_page_state(zone, NR_INACTIVE_ANON);
+        file  = zone_page_state(zone, NR_ACTIVE_FILE) +
+                zone_page_state(zone, NR_INACTIVE_FILE);
+        free  = zone_page_state(zone, NR_FREE_PAGES);
+
         /* If we have very few page cache pages, force-scan anon pages. */
         if (unlikely(file + free <= zone->pages_high)) {
                 percent[0] = 100;
@@ -1408,14 +1398,15 @@ static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
 /*
  * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
  */
-static unsigned long shrink_zone(int priority, struct zone *zone,
+static void shrink_zone(int priority, struct zone *zone,
                                 struct scan_control *sc)
 {
         unsigned long nr[NR_LRU_LISTS];
         unsigned long nr_to_scan;
-        unsigned long nr_reclaimed = 0;
         unsigned long percent[2];       /* anon @ 0; file @ 1 */
         enum lru_list l;
+        unsigned long nr_reclaimed = sc->nr_reclaimed;
+        unsigned long swap_cluster_max = sc->swap_cluster_max;
 
         get_scan_ratio(zone, sc, percent);
 
@@ -1431,7 +1422,7 @@ static unsigned long shrink_zone(int priority, struct zone *zone,
                         }
                         zone->lru[l].nr_scan += scan;
                         nr[l] = zone->lru[l].nr_scan;
-                        if (nr[l] >= sc->swap_cluster_max)
+                        if (nr[l] >= swap_cluster_max)
                                 zone->lru[l].nr_scan = 0;
                         else
                                 nr[l] = 0;
@@ -1450,16 +1441,28 @@ static unsigned long shrink_zone(int priority, struct zone *zone,
                                         nr[LRU_INACTIVE_FILE]) {
                 for_each_evictable_lru(l) {
                         if (nr[l]) {
-                                nr_to_scan = min(nr[l],
-                                        (unsigned long)sc->swap_cluster_max);
+                                nr_to_scan = min(nr[l], swap_cluster_max);
                                 nr[l] -= nr_to_scan;
 
                                 nr_reclaimed += shrink_list(l, nr_to_scan,
-                                                        zone, sc, priority);
+                                                            zone, sc, priority);
                         }
                 }
+                /*
+                 * On large memory systems, scan >> priority can become
+                 * really large. This is fine for the starting priority;
+                 * we want to put equal scanning pressure on each zone.
+                 * However, if the VM has a harder time of freeing pages,
+                 * with multiple processes reclaiming pages, the total
+                 * freeing target can get unreasonably large.
+                 */
+                if (nr_reclaimed > swap_cluster_max &&
+                        priority < DEF_PRIORITY && !current_is_kswapd())
+                        break;
         }
 
+        sc->nr_reclaimed = nr_reclaimed;
+
         /*
          * Even if we did not try to evict anon pages at all, we want to
          * rebalance the anon lru active/inactive ratio.
@@ -1470,7 +1473,6 @@ static unsigned long shrink_zone(int priority, struct zone *zone,
                 shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
 
         throttle_vm_writeout(sc->gfp_mask);
-        return nr_reclaimed;
 }
 
 /*
@@ -1484,16 +1486,13 @@ static unsigned long shrink_zone(int priority, struct zone *zone,
  * b) The zones may be over pages_high but they must go *over* pages_high to
  *    satisfy the `incremental min' zone defense algorithm.
  *
- * Returns the number of reclaimed pages.
- *
  * If a zone is deemed to be full of pinned pages then just give it a light
  * scan then give up on it.
  */
-static unsigned long shrink_zones(int priority, struct zonelist *zonelist,
+static void shrink_zones(int priority, struct zonelist *zonelist,
                                         struct scan_control *sc)
 {
         enum zone_type high_zoneidx = gfp_zone(sc->gfp_mask);
-        unsigned long nr_reclaimed = 0;
         struct zoneref *z;
         struct zone *zone;
 
@@ -1524,10 +1523,8 @@ static unsigned long shrink_zones(int priority, struct zonelist *zonelist,
                                                         priority);
                 }
 
-                nr_reclaimed += shrink_zone(priority, zone, sc);
+                shrink_zone(priority, zone, sc);
         }
-
-        return nr_reclaimed;
 }
 
 /*
@@ -1552,7 +1549,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
         int priority;
         unsigned long ret = 0;
         unsigned long total_scanned = 0;
-        unsigned long nr_reclaimed = 0;
         struct reclaim_state *reclaim_state = current->reclaim_state;
         unsigned long lru_pages = 0;
         struct zoneref *z;
@@ -1580,7 +1576,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                 sc->nr_scanned = 0;
                 if (!priority)
                         disable_swap_token();
-                nr_reclaimed += shrink_zones(priority, zonelist, sc);
+                shrink_zones(priority, zonelist, sc);
                 /*
                  * Don't shrink slabs when reclaiming memory from
                  * over limit cgroups
@@ -1588,13 +1584,13 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                 if (scan_global_lru(sc)) {
                         shrink_slab(sc->nr_scanned, sc->gfp_mask, lru_pages);
                         if (reclaim_state) {
-                                nr_reclaimed += reclaim_state->reclaimed_slab;
+                                sc->nr_reclaimed += reclaim_state->reclaimed_slab;
                                 reclaim_state->reclaimed_slab = 0;
                         }
                 }
                 total_scanned += sc->nr_scanned;
-                if (nr_reclaimed >= sc->swap_cluster_max) {
-                        ret = nr_reclaimed;
+                if (sc->nr_reclaimed >= sc->swap_cluster_max) {
+                        ret = sc->nr_reclaimed;
                         goto out;
                 }
 
@@ -1617,7 +1613,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
         }
         /* top priority shrink_zones still had more to do? don't OOM, then */
         if (!sc->all_unreclaimable && scan_global_lru(sc))
-                ret = nr_reclaimed;
+                ret = sc->nr_reclaimed;
 out:
         /*
          * Now that we've scanned all the zones at this priority level, note
@@ -1712,7 +1708,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
         int priority;
         int i;
         unsigned long total_scanned;
-        unsigned long nr_reclaimed;
         struct reclaim_state *reclaim_state = current->reclaim_state;
         struct scan_control sc = {
                 .gfp_mask = GFP_KERNEL,
@@ -1731,7 +1726,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order)
 
 loop_again:
         total_scanned = 0;
-        nr_reclaimed = 0;
+        sc.nr_reclaimed = 0;
         sc.may_writepage = !laptop_mode;
         count_vm_event(PAGEOUTRUN);
 
@@ -1817,11 +1812,11 @@ loop_again:
                          */
                         if (!zone_watermark_ok(zone, order, 8*zone->pages_high,
                                                 end_zone, 0))
-                                nr_reclaimed += shrink_zone(priority, zone, &sc);
+                                shrink_zone(priority, zone, &sc);
                         reclaim_state->reclaimed_slab = 0;
                         nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
                                                 lru_pages);
-                        nr_reclaimed += reclaim_state->reclaimed_slab;
+                        sc.nr_reclaimed += reclaim_state->reclaimed_slab;
                         total_scanned += sc.nr_scanned;
                         if (zone_is_all_unreclaimable(zone))
                                 continue;
@@ -1835,7 +1830,7 @@ loop_again:
                          * even in laptop mode
                          */
                         if (total_scanned > SWAP_CLUSTER_MAX * 2 &&
-                            total_scanned > nr_reclaimed + nr_reclaimed / 2)
+                            total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
                                 sc.may_writepage = 1;
                 }
                 if (all_zones_ok)
@@ -1853,7 +1848,7 @@ loop_again:
                  * matches the direct reclaim path behaviour in terms of impact
                  * on zone->*_priority.
                  */
-                if (nr_reclaimed >= SWAP_CLUSTER_MAX)
+                if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX)
                         break;
         }
 out:
@@ -1872,10 +1867,27 @@ out:
 
                 try_to_freeze();
 
+                /*
+                 * Fragmentation may mean that the system cannot be
+                 * rebalanced for high-order allocations in all zones.
+                 * At this point, if nr_reclaimed < SWAP_CLUSTER_MAX,
+                 * it means the zones have been fully scanned and are still
+                 * not balanced. For high-order allocations, there is
+                 * little point trying all over again as kswapd may
+                 * infinite loop.
+                 *
+                 * Instead, recheck all watermarks at order-0 as they
+                 * are the most important. If watermarks are ok, kswapd will go
+                 * back to sleep. High-order users can still perform direct
+                 * reclaim if they wish.
+                 */
+                if (sc.nr_reclaimed < SWAP_CLUSTER_MAX)
+                        order = sc.order = 0;
+
                 goto loop_again;
         }
 
-        return nr_reclaimed;
+        return sc.nr_reclaimed;
 }
 
 /*
@@ -2227,7 +2239,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
         struct task_struct *p = current;
         struct reclaim_state reclaim_state;
         int priority;
-        unsigned long nr_reclaimed = 0;
         struct scan_control sc = {
                 .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
                 .may_swap = !!(zone_reclaim_mode & RECLAIM_SWAP),
@@ -2260,9 +2271,9 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
                 priority = ZONE_RECLAIM_PRIORITY;
                 do {
                         note_zone_scanning_priority(zone, priority);
-                        nr_reclaimed += shrink_zone(priority, zone, &sc);
+                        shrink_zone(priority, zone, &sc);
                         priority--;
-                } while (priority >= 0 && nr_reclaimed < nr_pages);
+                } while (priority >= 0 && sc.nr_reclaimed < nr_pages);
         }
 
         slab_reclaimable = zone_page_state(zone, NR_SLAB_RECLAIMABLE);
@@ -2286,13 +2297,13 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
                  * Update nr_reclaimed by the number of slab pages we
                  * reclaimed from this zone.
                  */
-                nr_reclaimed += slab_reclaimable -
+                sc.nr_reclaimed += slab_reclaimable -
                         zone_page_state(zone, NR_SLAB_RECLAIMABLE);
         }
 
         p->reclaim_state = NULL;
         current->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE);
-        return nr_reclaimed >= nr_pages;
+        return sc.nr_reclaimed >= nr_pages;
 }
 
 int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
@@ -2472,7 +2483,7 @@ void scan_mapping_unevictable_pages(struct address_space *mapping)
  * back onto @zone's unevictable list.
  */
 #define SCAN_UNEVICTABLE_BATCH_SIZE 16UL /* arbitrary lock hold batch size */
-void scan_zone_unevictable_pages(struct zone *zone)
+static void scan_zone_unevictable_pages(struct zone *zone)
 {
         struct list_head *l_unevictable = &zone->lru[LRU_UNEVICTABLE].list;
         unsigned long scan;
@@ -2514,7 +2525,7 @@ void scan_zone_unevictable_pages(struct zone *zone)
  * that has possibly/probably made some previously unevictable pages
  * evictable.
  */
-void scan_all_zones_unevictable_pages(void)
+static void scan_all_zones_unevictable_pages(void)
 {
         struct zone *zone;