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
diff --git a/drivers/pps/clients/pps_parport.c b/drivers/pps/clients/pps_parport.c
index 38a8bbe..83797d8 100644
--- a/drivers/pps/clients/pps_parport.c
+++ b/drivers/pps/clients/pps_parport.c
@@ -195,7 +195,7 @@
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 a805474..56e6069 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -97,6 +97,11 @@
#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 @@
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 @@
if (mem_cgroup_disabled())
return 0;
- return memcg->css.id;
+ return memcg->id.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);
-}
+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 cb4b7e8..eca6f62 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -407,6 +407,7 @@
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 ac8664db..5339c89 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4057,6 +4057,60 @@
{ }, /* 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 @@
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 @@
#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 @@
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 @@
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 @@
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 @@
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 @@
!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 @@
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 a65dad7..82317ab 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -526,8 +526,8 @@
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 b7447ce..b0ac057 100644
--- a/tools/testing/radix-tree/tag_check.c
+++ b/tools/testing/radix-tree/tag_check.c
@@ -122,7 +122,7 @@
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 7cf6e17..b9d34b3 100644
--- a/tools/vm/slabinfo.c
+++ b/tools/vm/slabinfo.c
@@ -510,10 +510,11 @@
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)
