2 files changed, 65 insertions, 6 deletions

diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index ddb9a4c95968..c471c0c6e9ce 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -20,6 +20,7 @@ struct pid_namespace {
         struct pidmap pidmap[PIDMAP_ENTRIES];
         int last_pid;
         struct task_struct *child_reaper;
+        struct kmem_cache *pid_cachep;
 };
 
 extern struct pid_namespace init_pid_ns;
diff --git a/kernel/pid.c b/kernel/pid.c
index c6e3f9ffff87..42de9af8c524 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -32,7 +32,6 @@
 #define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift)
 static struct hlist_head *pid_hash;
 static int pidhash_shift;
-static struct kmem_cache *pid_cachep;
 struct pid init_struct_pid = INIT_STRUCT_PID;
 
 int pid_max = PID_MAX_DEFAULT;
@@ -176,11 +175,16 @@ static int next_pidmap(struct pid_namespace *pid_ns, int last)
 
 fastcall void put_pid(struct pid *pid)
 {
+        struct pid_namespace *ns;
+
         if (!pid)
                 return;
+
+        /* FIXME - this must be the namespace this pid lives in */
+        ns = &init_pid_ns;
         if ((atomic_read(&pid->count) == 1) ||
              atomic_dec_and_test(&pid->count))
-                kmem_cache_free(pid_cachep, pid);
+                kmem_cache_free(ns->pid_cachep, pid);
 }
 EXPORT_SYMBOL_GPL(put_pid);
 
@@ -208,12 +212,14 @@ struct pid *alloc_pid(void)
         struct pid *pid;
         enum pid_type type;
         int nr = -1;
+        struct pid_namespace *ns;
 
-        pid = kmem_cache_alloc(pid_cachep, GFP_KERNEL);
+        ns = current->nsproxy->pid_ns;
+        pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
         if (!pid)
                 goto out;
 
-        nr = alloc_pidmap(current->nsproxy->pid_ns);
+        nr = alloc_pidmap(ns);
         if (nr < 0)
                 goto out_free;
 
@@ -230,7 +236,7 @@ out:
         return pid;
 
 out_free:
-        kmem_cache_free(pid_cachep, pid);
+        kmem_cache_free(ns->pid_cachep, pid);
         pid = NULL;
         goto out;
 }
@@ -365,6 +371,56 @@ struct pid *find_ge_pid(int nr)
 }
 EXPORT_SYMBOL_GPL(find_get_pid);
 
+struct pid_cache {
+        int nr_ids;
+        char name[16];
+        struct kmem_cache *cachep;
+        struct list_head list;
+};
+
+static LIST_HEAD(pid_caches_lh);
+static DEFINE_MUTEX(pid_caches_mutex);
+
+/*
+ * creates the kmem cache to allocate pids from.
+ * @nr_ids: the number of numerical ids this pid will have to carry
+ */
+
+static struct kmem_cache *create_pid_cachep(int nr_ids)
+{
+        struct pid_cache *pcache;
+        struct kmem_cache *cachep;
+
+        mutex_lock(&pid_caches_mutex);
+        list_for_each_entry (pcache, &pid_caches_lh, list)
+                if (pcache->nr_ids == nr_ids)
+                        goto out;
+
+        pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
+        if (pcache == NULL)
+                goto err_alloc;
+
+        snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
+        cachep = kmem_cache_create(pcache->name,
+                        /* FIXME add numerical ids here */
+                        sizeof(struct pid), 0, SLAB_HWCACHE_ALIGN, NULL);
+        if (cachep == NULL)
+                goto err_cachep;
+
+        pcache->nr_ids = nr_ids;
+        pcache->cachep = cachep;
+        list_add(&pcache->list, &pid_caches_lh);
+out:
+        mutex_unlock(&pid_caches_mutex);
+        return pcache->cachep;
+
+err_cachep:
+        kfree(pcache);
+err_alloc:
+        mutex_unlock(&pid_caches_mutex);
+        return NULL;
+}
+
 struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns)
 {
         BUG_ON(!old_ns);
@@ -412,5 +468,7 @@ void __init pidmap_init(void)
         set_bit(0, init_pid_ns.pidmap[0].page);
         atomic_dec(&init_pid_ns.pidmap[0].nr_free);
 
-        pid_cachep = KMEM_CACHE(pid, SLAB_PANIC);
+        init_pid_ns.pid_cachep = create_pid_cachep(1);
+        if (init_pid_ns.pid_cachep == NULL)
+                panic("Can't create pid_1 cachep\n");
 }