slub: Allow removal of slab caches during boot
Serialize kmem_cache_create and kmem_cache_destroy using the slub_lock. Only
possible after the use of the slub_lock during dynamic dma creation has been
removed.
Then make sure that the setup of the slab sysfs entries does not race
with kmem_cache_create and kmem_cache destroy.
If a slab cache is removed before we have setup sysfs then simply skip over
the sysfs handling.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Roland Dreier <rdreier@cisco.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
diff --git a/mm/slub.c b/mm/slub.c
index f0f4036..fb6518e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2491,7 +2491,6 @@
s->refcount--;
if (!s->refcount) {
list_del(&s->list);
- up_write(&slub_lock);
if (kmem_cache_close(s)) {
printk(KERN_ERR "SLUB %s: %s called for cache that "
"still has objects.\n", s->name, __func__);
@@ -2500,8 +2499,8 @@
if (s->flags & SLAB_DESTROY_BY_RCU)
rcu_barrier();
sysfs_slab_remove(s);
- } else
- up_write(&slub_lock);
+ }
+ up_write(&slub_lock);
}
EXPORT_SYMBOL(kmem_cache_destroy);
@@ -3227,14 +3226,12 @@
*/
s->objsize = max(s->objsize, (int)size);
s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
- up_write(&slub_lock);
if (sysfs_slab_alias(s, name)) {
- down_write(&slub_lock);
s->refcount--;
- up_write(&slub_lock);
goto err;
}
+ up_write(&slub_lock);
return s;
}
@@ -3243,14 +3240,12 @@
if (kmem_cache_open(s, GFP_KERNEL, name,
size, align, flags, ctor)) {
list_add(&s->list, &slab_caches);
- up_write(&slub_lock);
if (sysfs_slab_add(s)) {
- down_write(&slub_lock);
list_del(&s->list);
- up_write(&slub_lock);
kfree(s);
goto err;
}
+ up_write(&slub_lock);
return s;
}
kfree(s);
@@ -4498,6 +4493,13 @@
static void sysfs_slab_remove(struct kmem_cache *s)
{
+ if (slab_state < SYSFS)
+ /*
+ * Sysfs has not been setup yet so no need to remove the
+ * cache from sysfs.
+ */
+ return;
+
kobject_uevent(&s->kobj, KOBJ_REMOVE);
kobject_del(&s->kobj);
kobject_put(&s->kobj);
@@ -4543,8 +4545,11 @@
struct kmem_cache *s;
int err;
+ down_write(&slub_lock);
+
slab_kset = kset_create_and_add("slab", &slab_uevent_ops, kernel_kobj);
if (!slab_kset) {
+ up_write(&slub_lock);
printk(KERN_ERR "Cannot register slab subsystem.\n");
return -ENOSYS;
}
@@ -4569,6 +4574,7 @@
kfree(al);
}
+ up_write(&slub_lock);
resiliency_test();
return 0;
}