mm, sl[aou]b: Move kmem_cache_create mutex handling to common code

Move the mutex handling into the common kmem_cache_create()
function.

Then we can also move more checks out of SLAB's kmem_cache_create()
into the common code.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

1 files changed, 40 insertions, 1 deletions

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 50e1ff10bff9..12637cee1f95 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -11,7 +11,8 @@
 #include <linux/memory.h>
 #include <linux/compiler.h>
 #include <linux/module.h>
-
+#include <linux/cpu.h>
+#include <linux/uaccess.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 #include <asm/page.h>
@@ -61,8 +62,46 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align
         }
 #endif
 
+        get_online_cpus();
+        mutex_lock(&slab_mutex);
+
+#ifdef CONFIG_DEBUG_VM
+        list_for_each_entry(s, &slab_caches, list) {
+                char tmp;
+                int res;
+
+                /*
+                 * This happens when the module gets unloaded and doesn't
+                 * destroy its slab cache and no-one else reuses the vmalloc
+                 * area of the module.  Print a warning.
+                 */
+                res = probe_kernel_address(s->name, tmp);
+                if (res) {
+                        printk(KERN_ERR
+                               "Slab cache with size %d has lost its name\n",
+                               s->object_size);
+                        continue;
+                }
+
+                if (!strcmp(s->name, name)) {
+                        printk(KERN_ERR "kmem_cache_create(%s): Cache name"
+                                " already exists.\n",
+                                name);
+                        dump_stack();
+                        s = NULL;
+                        goto oops;
+                }
+        }
+
+        WARN_ON(strchr(name, ' '));     /* It confuses parsers */
+#endif
+
         s = __kmem_cache_create(name, size, align, flags, ctor);
 
+oops:
+        mutex_unlock(&slab_mutex);
+        put_online_cpus();
+
 #ifdef CONFIG_DEBUG_VM
 out:
 #endif