Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "Five fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  pps: do not crash when failed to register
  tools/vm/slabinfo: fix an unintentional printf
  testing/radix-tree: fix a macro expansion bug
  radix-tree: fix radix_tree_iter_retry() for tagged iterators.
  mm: memcontrol: fix cgroup creation failure after many small jobs

7 files changed, 92 insertions, 27 deletions

diff --git a/drivers/pps/clients/pps_parport.c b/drivers/pps/clients/pps_parport.c
index 38a8bbe74810..83797d89c30f 100644
--- a/drivers/pps/clients/pps_parport.c
+++ b/drivers/pps/clients/pps_parport.c
@@ -195,7 +195,7 @@ static void parport_detach(struct parport *port)
         struct pps_client_pp *device;
 
         /* FIXME: oooh, this is ugly! */
-        if (strcmp(pardev->name, KBUILD_MODNAME))
+        if (!pardev || strcmp(pardev->name, KBUILD_MODNAME))
                 /* not our port */
                 return;
 
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index a805474df4ab..56e6069d2452 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -97,6 +97,11 @@ enum mem_cgroup_events_target {
 #define MEM_CGROUP_ID_SHIFT     16
 #define MEM_CGROUP_ID_MAX       USHRT_MAX
 
+struct mem_cgroup_id {
+        int id;
+        atomic_t ref;
+};
+
 struct mem_cgroup_stat_cpu {
         long count[MEMCG_NR_STAT];
         unsigned long events[MEMCG_NR_EVENTS];
@@ -172,6 +177,9 @@ enum memcg_kmem_state {
 struct mem_cgroup {
         struct cgroup_subsys_state css;
 
+        /* Private memcg ID. Used to ID objects that outlive the cgroup */
+        struct mem_cgroup_id id;
+
         /* Accounted resources */
         struct page_counter memory;
         struct page_counter swap;
@@ -330,22 +338,9 @@ static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
         if (mem_cgroup_disabled())
                 return 0;
 
-        return memcg->css.id;
-}
-
-/**
- * mem_cgroup_from_id - look up a memcg from an id
- * @id: the id to look up
- *
- * Caller must hold rcu_read_lock() and use css_tryget() as necessary.
- */
-static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
-{
-        struct cgroup_subsys_state *css;
-
-        css = css_from_id(id, &memory_cgrp_subsys);
-        return mem_cgroup_from_css(css);
+        return memcg->id.id;
 }
+struct mem_cgroup *mem_cgroup_from_id(unsigned short id);
 
 /**
  * parent_mem_cgroup - find the accounting parent of a memcg
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index cb4b7e8cee81..eca6f626c16e 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -407,6 +407,7 @@ static inline __must_check
 void **radix_tree_iter_retry(struct radix_tree_iter *iter)
 {
         iter->next_index = iter->index;
+        iter->tags = 0;
         return NULL;
 }
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ac8664db3823..5339c89dff63 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4057,6 +4057,60 @@ static struct cftype mem_cgroup_legacy_files[] = {
         { },    /* terminate */
 };
 
+/*
+ * Private memory cgroup IDR
+ *
+ * Swap-out records and page cache shadow entries need to store memcg
+ * references in constrained space, so we maintain an ID space that is
+ * limited to 16 bit (MEM_CGROUP_ID_MAX), limiting the total number of
+ * memory-controlled cgroups to 64k.
+ *
+ * However, there usually are many references to the oflline CSS after
+ * the cgroup has been destroyed, such as page cache or reclaimable
+ * slab objects, that don't need to hang on to the ID. We want to keep
+ * those dead CSS from occupying IDs, or we might quickly exhaust the
+ * relatively small ID space and prevent the creation of new cgroups
+ * even when there are much fewer than 64k cgroups - possibly none.
+ *
+ * Maintain a private 16-bit ID space for memcg, and allow the ID to
+ * be freed and recycled when it's no longer needed, which is usually
+ * when the CSS is offlined.
+ *
+ * The only exception to that are records of swapped out tmpfs/shmem
+ * pages that need to be attributed to live ancestors on swapin. But
+ * those references are manageable from userspace.
+ */
+
+static DEFINE_IDR(mem_cgroup_idr);
+
+static void mem_cgroup_id_get(struct mem_cgroup *memcg)
+{
+        atomic_inc(&memcg->id.ref);
+}
+
+static void mem_cgroup_id_put(struct mem_cgroup *memcg)
+{
+        if (atomic_dec_and_test(&memcg->id.ref)) {
+                idr_remove(&mem_cgroup_idr, memcg->id.id);
+                memcg->id.id = 0;
+
+                /* Memcg ID pins CSS */
+                css_put(&memcg->css);
+        }
+}
+
+/**
+ * mem_cgroup_from_id - look up a memcg from a memcg id
+ * @id: the memcg id to look up
+ *
+ * Caller must hold rcu_read_lock().
+ */
+struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
+{
+        WARN_ON_ONCE(!rcu_read_lock_held());
+        return idr_find(&mem_cgroup_idr, id);
+}
+
 static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
 {
         struct mem_cgroup_per_node *pn;
@@ -4116,6 +4170,12 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
         if (!memcg)
                 return NULL;
 
+        memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL,
+                                 1, MEM_CGROUP_ID_MAX,
+                                 GFP_KERNEL);
+        if (memcg->id.id < 0)
+                goto fail;
+
         memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
         if (!memcg->stat)
                 goto fail;
@@ -4142,8 +4202,11 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
 #ifdef CONFIG_CGROUP_WRITEBACK
         INIT_LIST_HEAD(&memcg->cgwb_list);
 #endif
+        idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
         return memcg;
 fail:
+        if (memcg->id.id > 0)
+                idr_remove(&mem_cgroup_idr, memcg->id.id);
         mem_cgroup_free(memcg);
         return NULL;
 }
@@ -4206,12 +4269,11 @@ fail:
         return ERR_PTR(-ENOMEM);
 }
 
-static int
-mem_cgroup_css_online(struct cgroup_subsys_state *css)
+static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
 {
-        if (css->id > MEM_CGROUP_ID_MAX)
-                return -ENOSPC;
-
+        /* Online state pins memcg ID, memcg ID pins CSS */
+        mem_cgroup_id_get(mem_cgroup_from_css(css));
+        css_get(css);
         return 0;
 }
 
@@ -4234,6 +4296,8 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
 
         memcg_offline_kmem(memcg);
         wb_memcg_offline(memcg);
+
+        mem_cgroup_id_put(memcg);
 }
 
 static void mem_cgroup_css_released(struct cgroup_subsys_state *css)
@@ -5756,6 +5820,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
         if (!memcg)
                 return;
 
+        mem_cgroup_id_get(memcg);
         oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg));
         VM_BUG_ON_PAGE(oldid, page);
         mem_cgroup_swap_statistics(memcg, true);
@@ -5774,6 +5839,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
         VM_BUG_ON(!irqs_disabled());
         mem_cgroup_charge_statistics(memcg, page, false, -1);
         memcg_check_events(memcg, page);
+
+        if (!mem_cgroup_is_root(memcg))
+                css_put(&memcg->css);
 }
 
 /*
@@ -5804,11 +5872,11 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
             !page_counter_try_charge(&memcg->swap, 1, &counter))
                 return -ENOMEM;
 
+        mem_cgroup_id_get(memcg);
         oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg));
         VM_BUG_ON_PAGE(oldid, page);
         mem_cgroup_swap_statistics(memcg, true);
 
-        css_get(&memcg->css);
         return 0;
 }
 
@@ -5837,7 +5905,7 @@ void mem_cgroup_uncharge_swap(swp_entry_t entry)
                                 page_counter_uncharge(&memcg->memsw, 1);
                 }
                 mem_cgroup_swap_statistics(memcg, false);
-                css_put(&memcg->css);
+                mem_cgroup_id_put(memcg);
         }
         rcu_read_unlock();
 }
diff --git a/mm/slab_common.c b/mm/slab_common.c
index a65dad7fdcd1..82317abb03ed 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -526,8 +526,8 @@ void memcg_create_kmem_cache(struct mem_cgroup *memcg,
                 goto out_unlock;
 
         cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf));
-        cache_name = kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name,
-                               css->id, memcg_name_buf);
+        cache_name = kasprintf(GFP_KERNEL, "%s(%llu:%s)", root_cache->name,
+                               css->serial_nr, memcg_name_buf);
         if (!cache_name)
                 goto out_unlock;
 
diff --git a/tools/testing/radix-tree/tag_check.c b/tools/testing/radix-tree/tag_check.c
index b7447ceb75e9..b0ac05741750 100644
--- a/tools/testing/radix-tree/tag_check.c
+++ b/tools/testing/radix-tree/tag_check.c
@@ -122,7 +122,7 @@ enum {
         NODE_TAGGED = 2,
 };
 
-#define THRASH_SIZE             1000 * 1000
+#define THRASH_SIZE             (1000 * 1000)
 #define N 127
 #define BATCH   33
 
diff --git a/tools/vm/slabinfo.c b/tools/vm/slabinfo.c
index 7cf6e1769903..b9d34b37c017 100644
--- a/tools/vm/slabinfo.c
+++ b/tools/vm/slabinfo.c
@@ -510,10 +510,11 @@ static void slab_stats(struct slabinfo *s)
                         s->alloc_node_mismatch, (s->alloc_node_mismatch * 100) / total);
         }
 
-        if (s->cmpxchg_double_fail || s->cmpxchg_double_cpu_fail)
+        if (s->cmpxchg_double_fail || s->cmpxchg_double_cpu_fail) {
                 printf("\nCmpxchg_double Looping\n------------------------\n");
                 printf("Locked Cmpxchg Double redos   %lu\nUnlocked Cmpxchg Double redos %lu\n",
                         s->cmpxchg_double_fail, s->cmpxchg_double_cpu_fail);
+        }
 }
 
 static void report(struct slabinfo *s)