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");
 }