[PATCH] SELinux: add slab cache for inode security struct
Add a slab cache for the SELinux inode security struct, one of which is
allocated for every inode instantiated by the system.
The memory savings are considerable.
On 64-bit, instead of the size-128 cache, we have a slab object of 96
bytes, saving 32 bytes per object. After booting, I see about 4000 of
these and then about 17,000 after a kernel compile. With this patch, we
save around 530KB of kernel memory in the latter case. On 32-bit, the
savings are about half of this.
Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index bdd0b32..ccaf988 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -117,6 +117,8 @@
static LIST_HEAD(superblock_security_head);
static DEFINE_SPINLOCK(sb_security_lock);
+static kmem_cache_t *sel_inode_cache;
+
/* Allocate and free functions for each kind of security blob. */
static int task_alloc_security(struct task_struct *task)
@@ -146,10 +148,11 @@
struct task_security_struct *tsec = current->security;
struct inode_security_struct *isec;
- isec = kzalloc(sizeof(struct inode_security_struct), GFP_KERNEL);
+ isec = kmem_cache_alloc(sel_inode_cache, SLAB_KERNEL);
if (!isec)
return -ENOMEM;
+ memset(isec, 0, sizeof(*isec));
init_MUTEX(&isec->sem);
INIT_LIST_HEAD(&isec->list);
isec->inode = inode;
@@ -172,7 +175,7 @@
spin_unlock(&sbsec->isec_lock);
inode->i_security = NULL;
- kfree(isec);
+ kmem_cache_free(sel_inode_cache, isec);
}
static int file_alloc_security(struct file *file)
@@ -4406,6 +4409,9 @@
tsec = current->security;
tsec->osid = tsec->sid = SECINITSID_KERNEL;
+ sel_inode_cache = kmem_cache_create("selinux_inode_security",
+ sizeof(struct inode_security_struct),
+ 0, SLAB_PANIC, NULL, NULL);
avc_init();
original_ops = secondary_ops = security_ops;