SLUB: Move sysfs operations outside of slub_lock

Sysfs can do a gazillion things when called.  Make sure that we do not call
any sysfs functions while holding the slub_lock.

Just protect the essentials:

1. The list of all slab caches
2. The kmalloc_dma array
3. The ref counters of the slabs.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 13 deletions

diff --git a/mm/slub.c b/mm/slub.c
index f976d2866e73..1c5d6a068556 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2192,12 +2192,13 @@ 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))
                         WARN_ON(1);
                 sysfs_slab_remove(s);
                 kfree(s);
-        }
-        up_write(&slub_lock);
+        } else
+                up_write(&slub_lock);
 }
 EXPORT_SYMBOL(kmem_cache_destroy);
 
@@ -2679,25 +2680,26 @@ 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))
                         goto err;
-        } else {
-                s = kmalloc(kmem_size, GFP_KERNEL);
-                if (s && kmem_cache_open(s, GFP_KERNEL, name,
+                return s;
+        }
+        s = kmalloc(kmem_size, GFP_KERNEL);
+        if (s) {
+                if (kmem_cache_open(s, GFP_KERNEL, name,
                                 size, align, flags, ctor)) {
-                        if (sysfs_slab_add(s)) {
-                                kfree(s);
-                                goto err;
-                        }
                         list_add(&s->list, &slab_caches);
-                } else
-                        kfree(s);
+                        up_write(&slub_lock);
+                        if (sysfs_slab_add(s))
+                                goto err;
+                        return s;
+                }
+                kfree(s);
         }
         up_write(&slub_lock);
-        return s;
 
 err:
-        up_write(&slub_lock);
         if (flags & SLAB_PANIC)
                 panic("Cannot create slabcache %s\n", name);
         else