add a kmem_cache for nsproxy objects

It should improve performance in some scenarii where a lot of
these nsproxy objects are created by unsharing namespaces. This is
a typical use of virtual servers that are being created or entered.

This is also a good tool to find leaks and gather statistics on
namespace usage.

Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 17 insertions, 4 deletions

diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index 15a6015a849d..4b7fcc8f9a48 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -21,6 +21,8 @@
 #include <linux/utsname.h>
 #include <linux/pid_namespace.h>
 
+static struct kmem_cache *nsproxy_cachep;
+
 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 static inline void get_nsproxy(struct nsproxy *ns)
@@ -43,9 +45,11 @@ static inline struct nsproxy *clone_nsproxy(struct nsproxy *orig)
 {
         struct nsproxy *ns;
 
-        ns = kmemdup(orig, sizeof(struct nsproxy), GFP_KERNEL);
-        if (ns)
+        ns = kmem_cache_alloc(nsproxy_cachep, GFP_KERNEL);
+        if (ns) {
+                memcpy(ns, orig, sizeof(struct nsproxy));
                 atomic_set(&ns->count, 1);
+        }
         return ns;
 }
 
@@ -109,7 +113,7 @@ out_uts:
         if (new_nsp->mnt_ns)
                 put_mnt_ns(new_nsp->mnt_ns);
 out_ns:
-        kfree(new_nsp);
+        kmem_cache_free(nsproxy_cachep, new_nsp);
         return ERR_PTR(err);
 }
 
@@ -160,7 +164,7 @@ void free_nsproxy(struct nsproxy *ns)
                 put_pid_ns(ns->pid_ns);
         if (ns->user_ns)
                 put_user_ns(ns->user_ns);
-        kfree(ns);
+        kmem_cache_free(nsproxy_cachep, ns);
 }
 
 /*
@@ -185,3 +189,12 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags,
                 err = PTR_ERR(*new_nsp);
         return err;
 }
+
+static int __init nsproxy_cache_init(void)
+{
+        nsproxy_cachep = kmem_cache_create("nsproxy", sizeof(struct nsproxy),
+                                           0, SLAB_PANIC, NULL, NULL);
+        return 0;
+}
+
+module_init(nsproxy_cache_init);