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authorPavel Emelyanov <xemul@parallels.com>2011-01-12 20:00:46 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 11:03:18 -0500
commit6164281ab7a4d3bd42588d6b25984e960a2e032f (patch)
treeea4bf309efed7ec922431c6e5b5d659919eaf2ae
parente020e742e5dbd8c44d31706995dc13ddc732e274 (diff)
user_ns: improve the user_ns on-the-slab packaging
Currently on 64-bit arch the user_namespace is 2096 and when being kmalloc-ed it resides on a 4k slab wasting 2003 bytes. If we allocate a separate cache for it and reduce the hash size from 128 to 64 chains the packaging becomes *much* better - the struct is 1072 bytes and the hole between is 98 bytes. [akpm@linux-foundation.org: s/__initcall/module_init/] Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Acked-by: Serge E. Hallyn <serge@hallyn.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/user_namespace.h2
-rw-r--r--kernel/user_namespace.c15
2 files changed, 13 insertions, 4 deletions
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index 8178156711f9..faf467944baf 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -6,7 +6,7 @@
6#include <linux/sched.h> 6#include <linux/sched.h>
7#include <linux/err.h> 7#include <linux/err.h>
8 8
9#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 8) 9#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 7)
10#define UIDHASH_SZ (1 << UIDHASH_BITS) 10#define UIDHASH_SZ (1 << UIDHASH_BITS)
11 11
12struct user_namespace { 12struct user_namespace {
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 25915832291a..9da289c34f22 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -12,6 +12,8 @@
12#include <linux/highuid.h> 12#include <linux/highuid.h>
13#include <linux/cred.h> 13#include <linux/cred.h>
14 14
15static struct kmem_cache *user_ns_cachep __read_mostly;
16
15/* 17/*
16 * Create a new user namespace, deriving the creator from the user in the 18 * Create a new user namespace, deriving the creator from the user in the
17 * passed credentials, and replacing that user with the new root user for the 19 * passed credentials, and replacing that user with the new root user for the
@@ -26,7 +28,7 @@ int create_user_ns(struct cred *new)
26 struct user_struct *root_user; 28 struct user_struct *root_user;
27 int n; 29 int n;
28 30
29 ns = kmalloc(sizeof(struct user_namespace), GFP_KERNEL); 31 ns = kmem_cache_alloc(user_ns_cachep, GFP_KERNEL);
30 if (!ns) 32 if (!ns)
31 return -ENOMEM; 33 return -ENOMEM;
32 34
@@ -38,7 +40,7 @@ int create_user_ns(struct cred *new)
38 /* Alloc new root user. */ 40 /* Alloc new root user. */
39 root_user = alloc_uid(ns, 0); 41 root_user = alloc_uid(ns, 0);
40 if (!root_user) { 42 if (!root_user) {
41 kfree(ns); 43 kmem_cache_free(user_ns_cachep, ns);
42 return -ENOMEM; 44 return -ENOMEM;
43 } 45 }
44 46
@@ -71,7 +73,7 @@ static void free_user_ns_work(struct work_struct *work)
71 struct user_namespace *ns = 73 struct user_namespace *ns =
72 container_of(work, struct user_namespace, destroyer); 74 container_of(work, struct user_namespace, destroyer);
73 free_uid(ns->creator); 75 free_uid(ns->creator);
74 kfree(ns); 76 kmem_cache_free(user_ns_cachep, ns);
75} 77}
76 78
77void free_user_ns(struct kref *kref) 79void free_user_ns(struct kref *kref)
@@ -126,3 +128,10 @@ gid_t user_ns_map_gid(struct user_namespace *to, const struct cred *cred, gid_t
126 /* No useful relationship so no mapping */ 128 /* No useful relationship so no mapping */
127 return overflowgid; 129 return overflowgid;
128} 130}
131
132static __init int user_namespaces_init(void)
133{
134 user_ns_cachep = KMEM_CACHE(user_namespace, SLAB_PANIC);
135 return 0;
136}
137module_init(user_namespaces_init);