mm, sl[aou]b: Use a common mutex definition
Use the mutex definition from SLAB and make it the common way to take a sleeping lock.
This has the effect of using a mutex instead of a rw semaphore for SLUB.
SLOB gains the use of a mutex for kmem_cache_create serialization.
Not needed now but SLOB may acquire some more features later (like slabinfo
/ sysfs support) through the expansion of the common code that will
need this.
Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
diff --git a/mm/slub.c b/mm/slub.c
index 4c385164..8c4fd37 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -36,13 +36,13 @@
/*
* Lock order:
- * 1. slub_lock (Global Semaphore)
+ * 1. slab_mutex (Global Mutex)
* 2. node->list_lock
* 3. slab_lock(page) (Only on some arches and for debugging)
*
- * slub_lock
+ * slab_mutex
*
- * The role of the slub_lock is to protect the list of all the slabs
+ * The role of the slab_mutex is to protect the list of all the slabs
* and to synchronize major metadata changes to slab cache structures.
*
* The slab_lock is only used for debugging and on arches that do not
@@ -183,10 +183,6 @@
static struct notifier_block slab_notifier;
#endif
-/* A list of all slab caches on the system */
-static DECLARE_RWSEM(slub_lock);
-static LIST_HEAD(slab_caches);
-
/*
* Tracking user of a slab.
*/
@@ -3177,11 +3173,11 @@
*/
void kmem_cache_destroy(struct kmem_cache *s)
{
- down_write(&slub_lock);
+ mutex_lock(&slab_mutex);
s->refcount--;
if (!s->refcount) {
list_del(&s->list);
- up_write(&slub_lock);
+ mutex_unlock(&slab_mutex);
if (kmem_cache_close(s)) {
printk(KERN_ERR "SLUB %s: %s called for cache that "
"still has objects.\n", s->name, __func__);
@@ -3191,7 +3187,7 @@
rcu_barrier();
sysfs_slab_remove(s);
} else
- up_write(&slub_lock);
+ mutex_unlock(&slab_mutex);
}
EXPORT_SYMBOL(kmem_cache_destroy);
@@ -3253,7 +3249,7 @@
/*
* This function is called with IRQs disabled during early-boot on
- * single CPU so there's no need to take slub_lock here.
+ * single CPU so there's no need to take slab_mutex here.
*/
if (!kmem_cache_open(s, name, size, ARCH_KMALLOC_MINALIGN,
flags, NULL))
@@ -3538,10 +3534,10 @@
{
struct kmem_cache *s;
- down_read(&slub_lock);
+ mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_caches, list)
kmem_cache_shrink(s);
- up_read(&slub_lock);
+ mutex_unlock(&slab_mutex);
return 0;
}
@@ -3562,7 +3558,7 @@
if (offline_node < 0)
return;
- down_read(&slub_lock);
+ mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_caches, list) {
n = get_node(s, offline_node);
if (n) {
@@ -3578,7 +3574,7 @@
kmem_cache_free(kmem_cache_node, n);
}
}
- up_read(&slub_lock);
+ mutex_unlock(&slab_mutex);
}
static int slab_mem_going_online_callback(void *arg)
@@ -3601,7 +3597,7 @@
* allocate a kmem_cache_node structure in order to bring the node
* online.
*/
- down_read(&slub_lock);
+ mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_caches, list) {
/*
* XXX: kmem_cache_alloc_node will fallback to other nodes
@@ -3617,7 +3613,7 @@
s->node[nid] = n;
}
out:
- up_read(&slub_lock);
+ mutex_unlock(&slab_mutex);
return ret;
}
@@ -3915,7 +3911,7 @@
struct kmem_cache *s;
char *n;
- down_write(&slub_lock);
+ mutex_lock(&slab_mutex);
s = find_mergeable(size, align, flags, name, ctor);
if (s) {
s->refcount++;
@@ -3930,7 +3926,7 @@
s->refcount--;
goto err;
}
- up_write(&slub_lock);
+ mutex_unlock(&slab_mutex);
return s;
}
@@ -3943,9 +3939,9 @@
if (kmem_cache_open(s, n,
size, align, flags, ctor)) {
list_add(&s->list, &slab_caches);
- up_write(&slub_lock);
+ mutex_unlock(&slab_mutex);
if (sysfs_slab_add(s)) {
- down_write(&slub_lock);
+ mutex_lock(&slab_mutex);
list_del(&s->list);
kfree(n);
kfree(s);
@@ -3957,7 +3953,7 @@
}
kfree(n);
err:
- up_write(&slub_lock);
+ mutex_unlock(&slab_mutex);
return s;
}
@@ -3978,13 +3974,13 @@
case CPU_UP_CANCELED_FROZEN:
case CPU_DEAD:
case CPU_DEAD_FROZEN:
- down_read(&slub_lock);
+ mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_caches, list) {
local_irq_save(flags);
__flush_cpu_slab(s, cpu);
local_irq_restore(flags);
}
- up_read(&slub_lock);
+ mutex_unlock(&slab_mutex);
break;
default:
break;
@@ -5360,11 +5356,11 @@
struct kmem_cache *s;
int err;
- down_write(&slub_lock);
+ mutex_lock(&slab_mutex);
slab_kset = kset_create_and_add("slab", &slab_uevent_ops, kernel_kobj);
if (!slab_kset) {
- up_write(&slub_lock);
+ mutex_unlock(&slab_mutex);
printk(KERN_ERR "Cannot register slab subsystem.\n");
return -ENOSYS;
}
@@ -5389,7 +5385,7 @@
kfree(al);
}
- up_write(&slub_lock);
+ mutex_unlock(&slab_mutex);
resiliency_test();
return 0;
}
@@ -5415,7 +5411,7 @@
{
loff_t n = *pos;
- down_read(&slub_lock);
+ mutex_lock(&slab_mutex);
if (!n)
print_slabinfo_header(m);
@@ -5429,7 +5425,7 @@
static void s_stop(struct seq_file *m, void *p)
{
- up_read(&slub_lock);
+ mutex_unlock(&slab_mutex);
}
static int s_show(struct seq_file *m, void *p)