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Commit 2bce6485 authored by Christoph Lameter's avatar Christoph Lameter Committed by Pekka Enberg
Browse files

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: default avatarChristoph Lameter <cl@linux-foundation.org>
Signed-off-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
parent e438444d

mm/slub.c

+15 −9
Original line number Diff line number Diff line
@@ -2491,7 +2491,6 @@ void kmem_cache_destroy(struct kmem_cache *s) 
	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__);
@@ -2500,7 +2499,7 @@ void kmem_cache_destroy(struct kmem_cache *s) 
		if (s->flags & SLAB_DESTROY_BY_RCU)

			rcu_barrier();

		sysfs_slab_remove(s);

	} else

	}

	up_write(&slub_lock);

}

EXPORT_SYMBOL(kmem_cache_destroy);
@@ -3227,14 +3226,12 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, 
		 */

		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 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, 
		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 int sysfs_slab_add(struct kmem_cache *s) 


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 @@ static int __init slab_sysfs_init(void) 
	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 @@ static int __init slab_sysfs_init(void) 
		kfree(al);

	}



	up_write(&slub_lock);

	resiliency_test();

	return 0;

}