3 files changed, 120 insertions, 121 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d1b315e98627..e2df1c1fb41f 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2132,7 +2132,7 @@ bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
  */
 
 /* lookup first element intersecting start-end */
-/* Caller holds sp->mutex */
+/* Caller holds sp->lock */
 static struct sp_node *
 sp_lookup(struct shared_policy *sp, unsigned long start, unsigned long end)
 {
@@ -2196,13 +2196,13 @@ mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx)
 
         if (!sp->root.rb_node)
                 return NULL;
-        mutex_lock(&sp->mutex);
+        spin_lock(&sp->lock);
         sn = sp_lookup(sp, idx, idx+1);
         if (sn) {
                 mpol_get(sn->policy);
                 pol = sn->policy;
         }
-        mutex_unlock(&sp->mutex);
+        spin_unlock(&sp->lock);
         return pol;
 }
 
@@ -2328,6 +2328,14 @@ static void sp_delete(struct shared_policy *sp, struct sp_node *n)
         sp_free(n);
 }
 
+static void sp_node_init(struct sp_node *node, unsigned long start,
+                        unsigned long end, struct mempolicy *pol)
+{
+        node->start = start;
+        node->end = end;
+        node->policy = pol;
+}
+
 static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
                                 struct mempolicy *pol)
 {
@@ -2344,10 +2352,7 @@ static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
                 return NULL;
         }
         newpol->flags |= MPOL_F_SHARED;
-
-        n->start = start;
-        n->end = end;
-        n->policy = newpol;
+        sp_node_init(n, start, end, newpol);
 
         return n;
 }
@@ -2357,9 +2362,12 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
                                  unsigned long end, struct sp_node *new)
 {
         struct sp_node *n;
+        struct sp_node *n_new = NULL;
+        struct mempolicy *mpol_new = NULL;
         int ret = 0;
 
-        mutex_lock(&sp->mutex);
+restart:
+        spin_lock(&sp->lock);
         n = sp_lookup(sp, start, end);
         /* Take care of old policies in the same range. */
         while (n && n->start < end) {
@@ -2372,14 +2380,16 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
                 } else {
                         /* Old policy spanning whole new range. */
                         if (n->end > end) {
-                                struct sp_node *new2;
-                                new2 = sp_alloc(end, n->end, n->policy);
-                                if (!new2) {
-                                        ret = -ENOMEM;
-                                        goto out;
-                                }
+                                if (!n_new)
+                                        goto alloc_new;
+
+                                *mpol_new = *n->policy;
+                                atomic_set(&mpol_new->refcnt, 1);
+                                sp_node_init(n_new, n->end, end, mpol_new);
+                                sp_insert(sp, n_new);
                                 n->end = start;
-                                sp_insert(sp, new2);
+                                n_new = NULL;
+                                mpol_new = NULL;
                                 break;
                         } else
                                 n->end = start;
@@ -2390,9 +2400,27 @@ static int shared_policy_replace(struct shared_policy *sp, unsigned long start,
         }
         if (new)
                 sp_insert(sp, new);
-out:
-        mutex_unlock(&sp->mutex);
+        spin_unlock(&sp->lock);
+        ret = 0;
+
+err_out:
+        if (mpol_new)
+                mpol_put(mpol_new);
+        if (n_new)
+                kmem_cache_free(sn_cache, n_new);
+
         return ret;
+
+alloc_new:
+        spin_unlock(&sp->lock);
+        ret = -ENOMEM;
+        n_new = kmem_cache_alloc(sn_cache, GFP_KERNEL);
+        if (!n_new)
+                goto err_out;
+        mpol_new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
+        if (!mpol_new)
+                goto err_out;
+        goto restart;
 }
 
 /**
@@ -2410,7 +2438,7 @@ void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
         int ret;
 
         sp->root = RB_ROOT;             /* empty tree == default mempolicy */
-        mutex_init(&sp->mutex);
+        spin_lock_init(&sp->lock);
 
         if (mpol) {
                 struct vm_area_struct pvma;
@@ -2476,14 +2504,14 @@ void mpol_free_shared_policy(struct shared_policy *p)
 
         if (!p->root.rb_node)
                 return;
-        mutex_lock(&p->mutex);
+        spin_lock(&p->lock);
         next = rb_first(&p->root);
         while (next) {
                 n = rb_entry(next, struct sp_node, nd);
                 next = rb_next(&n->nd);
                 sp_delete(p, n);
         }
-        mutex_unlock(&p->mutex);
+        spin_unlock(&p->lock);
 }
 
 #ifdef CONFIG_NUMA_BALANCING
@@ -2595,8 +2623,7 @@ void numa_default_policy(void)
  */
 
 /*
- * "local" is pseudo-policy:  MPOL_PREFERRED with MPOL_F_LOCAL flag
- * Used only for mpol_parse_str() and mpol_to_str()
+ * "local" is implemented internally by MPOL_PREFERRED with MPOL_F_LOCAL flag.
  */
 static const char * const policy_modes[] =
 {
@@ -2610,28 +2637,20 @@ static const char * const policy_modes[] =
 
 #ifdef CONFIG_TMPFS
 /**
- * mpol_parse_str - parse string to mempolicy
+ * mpol_parse_str - parse string to mempolicy, for tmpfs mpol mount option.
  * @str:  string containing mempolicy to parse
  * @mpol:  pointer to struct mempolicy pointer, returned on success.
- * @no_context:  flag whether to "contextualize" the mempolicy
  *
  * Format of input:
  *      <mode>[=<flags>][:<nodelist>]
  *
- * if @no_context is true, save the input nodemask in w.user_nodemask in
- * the returned mempolicy.  This will be used to "clone" the mempolicy in
- * a specific context [cpuset] at a later time.  Used to parse tmpfs mpol
- * mount option.  Note that if 'static' or 'relative' mode flags were
- * specified, the input nodemask will already have been saved.  Saving
- * it again is redundant, but safe.
- *
  * On success, returns 0, else 1
  */
-int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
+int mpol_parse_str(char *str, struct mempolicy **mpol)
 {
         struct mempolicy *new = NULL;
         unsigned short mode;
-        unsigned short uninitialized_var(mode_flags);
+        unsigned short mode_flags;
         nodemask_t nodes;
         char *nodelist = strchr(str, ':');
         char *flags = strchr(str, '=');
@@ -2719,24 +2738,23 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
         if (IS_ERR(new))
                 goto out;
 
-        if (no_context) {
-                /* save for contextualization */
-                new->w.user_nodemask = nodes;
-        } else {
-                int ret;
-                NODEMASK_SCRATCH(scratch);
-                if (scratch) {
-                        task_lock(current);
-                        ret = mpol_set_nodemask(new, &nodes, scratch);
-                        task_unlock(current);
-                } else
-                        ret = -ENOMEM;
-                NODEMASK_SCRATCH_FREE(scratch);
-                if (ret) {
-                        mpol_put(new);
-                        goto out;
-                }
-        }
+        /*
+         * Save nodes for mpol_to_str() to show the tmpfs mount options
+         * for /proc/mounts, /proc/pid/mounts and /proc/pid/mountinfo.
+         */
+        if (mode != MPOL_PREFERRED)
+                new->v.nodes = nodes;
+        else if (nodelist)
+                new->v.preferred_node = first_node(nodes);
+        else
+                new->flags |= MPOL_F_LOCAL;
+
+        /*
+         * Save nodes for contextualization: this will be used to "clone"
+         * the mempolicy in a specific context [cpuset] at a later time.
+         */
+        new->w.user_nodemask = nodes;
+
         err = 0;
 
 out:
@@ -2756,13 +2774,12 @@ out:
  * @buffer:  to contain formatted mempolicy string
  * @maxlen:  length of @buffer
  * @pol:  pointer to mempolicy to be formatted
- * @no_context:  "context free" mempolicy - use nodemask in w.user_nodemask
  *
  * Convert a mempolicy into a string.
  * Returns the number of characters in buffer (if positive)
  * or an error (negative)
  */
-int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol, int no_context)
+int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
 {
         char *p = buffer;
         int l;
@@ -2788,7 +2805,7 @@ int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol, int no_context)
         case MPOL_PREFERRED:
                 nodes_clear(nodes);
                 if (flags & MPOL_F_LOCAL)
-                        mode = MPOL_LOCAL;      /* pseudo-policy */
+                        mode = MPOL_LOCAL;
                 else
                         node_set(pol->v.preferred_node, nodes);
                 break;
@@ -2796,10 +2813,7 @@ int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol, int no_context)
         case MPOL_BIND:
                 /* Fall through */
         case MPOL_INTERLEAVE:
-                if (no_context)
-                        nodes = pol->w.user_nodemask;
-                else
-                        nodes = pol->v.nodes;
+                nodes = pol->v.nodes;
                 break;
 
         default:
diff --git a/mm/shmem.c b/mm/shmem.c
index 5c90d84c2b02..5dd56f6efdbd 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -889,7 +889,7 @@ static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
         if (!mpol || mpol->mode == MPOL_DEFAULT)
                 return;         /* show nothing */
 
-        mpol_to_str(buffer, sizeof(buffer), mpol, 1);
+        mpol_to_str(buffer, sizeof(buffer), mpol);
 
         seq_printf(seq, ",mpol=%s", buffer);
 }
@@ -2463,7 +2463,7 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
                         if (!gid_valid(sbinfo->gid))
                                 goto bad_val;
                 } else if (!strcmp(this_char,"mpol")) {
-                        if (mpol_parse_str(value, &sbinfo->mpol, 1))
+                        if (mpol_parse_str(value, &sbinfo->mpol))
                                 goto bad_val;
                 } else {
                         printk(KERN_ERR "tmpfs: Bad mount option %s\n",
diff --git a/mm/vmscan.c b/mm/vmscan.c
index adc7e9058181..16b42af393ac 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2452,12 +2452,16 @@ static bool zone_balanced(struct zone *zone, int order,
 }
 
 /*
- * pgdat_balanced is used when checking if a node is balanced for high-order
- * allocations. Only zones that meet watermarks and are in a zone allowed
- * by the callers classzone_idx are added to balanced_pages. The total of
- * balanced pages must be at least 25% of the zones allowed by classzone_idx
- * for the node to be considered balanced. Forcing all zones to be balanced
- * for high orders can cause excessive reclaim when there are imbalanced zones.
+ * pgdat_balanced() is used when checking if a node is balanced.
+ *
+ * For order-0, all zones must be balanced!
+ *
+ * For high-order allocations only zones that meet watermarks and are in a
+ * zone allowed by the callers classzone_idx are added to balanced_pages. The
+ * total of balanced pages must be at least 25% of the zones allowed by
+ * classzone_idx for the node to be considered balanced. Forcing all zones to
+ * be balanced for high orders can cause excessive reclaim when there are
+ * imbalanced zones.
  * The choice of 25% is due to
  *   o a 16M DMA zone that is balanced will not balance a zone on any
  *     reasonable sized machine
@@ -2467,17 +2471,43 @@ static bool zone_balanced(struct zone *zone, int order,
  *     Similarly, on x86-64 the Normal zone would need to be at least 1G
  *     to balance a node on its own. These seemed like reasonable ratios.
  */
-static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
-                                                int classzone_idx)
+static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx)
 {
         unsigned long present_pages = 0;
+        unsigned long balanced_pages = 0;
         int i;
 
-        for (i = 0; i <= classzone_idx; i++)
-                present_pages += pgdat->node_zones[i].present_pages;
+        /* Check the watermark levels */
+        for (i = 0; i <= classzone_idx; i++) {
+                struct zone *zone = pgdat->node_zones + i;
 
-        /* A special case here: if zone has no page, we think it's balanced */
-        return balanced_pages >= (present_pages >> 2);
+                if (!populated_zone(zone))
+                        continue;
+
+                present_pages += zone->present_pages;
+
+                /*
+                 * A special case here:
+                 *
+                 * balance_pgdat() skips over all_unreclaimable after
+                 * DEF_PRIORITY. Effectively, it considers them balanced so
+                 * they must be considered balanced here as well!
+                 */
+                if (zone->all_unreclaimable) {
+                        balanced_pages += zone->present_pages;
+                        continue;
+                }
+
+                if (zone_balanced(zone, order, 0, i))
+                        balanced_pages += zone->present_pages;
+                else if (!order)
+                        return false;
+        }
+
+        if (order)
+                return balanced_pages >= (present_pages >> 2);
+        else
+                return true;
 }
 
 /*
@@ -2489,10 +2519,6 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced_pages,
 static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
                                         int classzone_idx)
 {
-        int i;
-        unsigned long balanced = 0;
-        bool all_zones_ok = true;
-
         /* If a direct reclaimer woke kswapd within HZ/10, it's premature */
         if (remaining)
                 return false;
@@ -2511,39 +2537,7 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
                 return false;
         }
 
-        /* Check the watermark levels */
-        for (i = 0; i <= classzone_idx; i++) {
-                struct zone *zone = pgdat->node_zones + i;
-
-                if (!populated_zone(zone))
-                        continue;
-
-                /*
-                 * balance_pgdat() skips over all_unreclaimable after
-                 * DEF_PRIORITY. Effectively, it considers them balanced so
-                 * they must be considered balanced here as well if kswapd
-                 * is to sleep
-                 */
-                if (zone->all_unreclaimable) {
-                        balanced += zone->present_pages;
-                        continue;
-                }
-
-                if (!zone_balanced(zone, order, 0, i))
-                        all_zones_ok = false;
-                else
-                        balanced += zone->present_pages;
-        }
-
-        /*
-         * For high-order requests, the balanced zones must contain at least
-         * 25% of the nodes pages for kswapd to sleep. For order-0, all zones
-         * must be balanced
-         */
-        if (order)
-                return pgdat_balanced(pgdat, balanced, classzone_idx);
-        else
-                return all_zones_ok;
+        return pgdat_balanced(pgdat, order, classzone_idx);
 }
 
 /*
@@ -2571,7 +2565,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
                                                         int *classzone_idx)
 {
         struct zone *unbalanced_zone;
-        unsigned long balanced;
         int i;
         int end_zone = 0;       /* Inclusive.  0 = ZONE_DMA */
         unsigned long total_scanned;
@@ -2605,7 +2598,6 @@ loop_again:
                 int has_under_min_watermark_zone = 0;
 
                 unbalanced_zone = NULL;
-                balanced = 0;
 
                 /*
                  * Scan in the highmem->dma direction for the highest
@@ -2761,8 +2753,6 @@ loop_again:
                                  * speculatively avoid congestion waits
                                  */
                                 zone_clear_flag(zone, ZONE_CONGESTED);
-                                if (i <= *classzone_idx)
-                                        balanced += zone->present_pages;
                         }
 
                 }
@@ -2776,7 +2766,7 @@ loop_again:
                                 pfmemalloc_watermark_ok(pgdat))
                         wake_up(&pgdat->pfmemalloc_wait);
 
-                if (!unbalanced_zone || (order && pgdat_balanced(pgdat, balanced, *classzone_idx)))
+                if (pgdat_balanced(pgdat, order, *classzone_idx))
                         break;          /* kswapd: all done */
                 /*
                  * OK, kswapd is getting into trouble.  Take a nap, then take
@@ -2785,7 +2775,7 @@ loop_again:
                 if (total_scanned && (sc.priority < DEF_PRIORITY - 2)) {
                         if (has_under_min_watermark_zone)
                                 count_vm_event(KSWAPD_SKIP_CONGESTION_WAIT);
-                        else
+                        else if (unbalanced_zone)
                                 wait_iff_congested(unbalanced_zone, BLK_RW_ASYNC, HZ/10);
                 }
 
@@ -2800,12 +2790,7 @@ loop_again:
         } while (--sc.priority >= 0);
 out:
 
-        /*
-         * order-0: All zones must meet high watermark for a balanced node
-         * high-order: Balanced zones must make up at least 25% of the node
-         *             for the node to be balanced
-         */
-        if (unbalanced_zone && (!order || !pgdat_balanced(pgdat, balanced, *classzone_idx))) {
+        if (!pgdat_balanced(pgdat, order, *classzone_idx)) {
                 cond_resched();
 
                 try_to_freeze();