Patch "slub: Do not hold slub_lock when calling sysfs_slab_add()" has been added to the 3.2-stable tree

This is a note to let you know that I've just added the patch titled

slub: Do not hold slub_lock when calling sysfs_slab_add()

to the 3.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
slub-do-not-hold-slub_lock-when-calling-sysfs_slab_add.patch
and it can be found in the queue-3.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Christoph Lameter <[email protected]>
Date: Tue, 17 Jan 2012 09:27:31 -0600
Subject: slub: Do not hold slub_lock when calling sysfs_slab_add()

From: Christoph Lameter <[email protected]>

commit 66c4c35c6bc5a1a452b024cf0364635b28fd94e4 upstream.

sysfs_slab_add() calls various sysfs functions that actually may end up in userspace doing all sorts of things.

Release the slub_lock after adding the kmem_cache structure to the list. At that point the address of the kmem_cache is not known so we are guaranteed exlusive access to the following modifications to the kmem_cache structure.

If the sysfs_slab_add fails then reacquire the slub_lock to remove the kmem_cache structure from the list.

---
 mm/slub.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

@@ -3911,13 +3911,14 @@ struct kmem_cache *kmem_cache_create(con
 		if (kmem_cache_open(s, n,
 				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);
 				kfree(n);
 				kfree(s);
 				goto err;
 			}
-			up_write(&slub_lock);
 			return s;
 		}
 		kfree(n);

Patches currently in stable-queue which might be from [email protected] are

queue-3.2/slub-do-not-hold-slub_lock-when-calling-sysfs_slab_add.patch