slab_common: fix the check for duplicate slab names

The patch 3e374919b3 is supposed to fix the
problem where kmem_cache_create incorrectly reports duplicate cache name
and fails. The problem is described in the header of that patch.

However, the patch doesn't really fix the problem because of these
reasons:

* the logic to test for debugging is reversed. It was intended to perform
  the check only if slub debugging is enabled (which implies that caches
  with the same parameters are not merged). Therefore, there should be
  #if !defined(CONFIG_SLUB) || defined(CONFIG_SLUB_DEBUG_ON)
  The current code has the condition reversed and performs the test if
  debugging is disabled.

* slub debugging may be enabled or disabled based on kernel command line,
  CONFIG_SLUB_DEBUG_ON is just the default settings. Therefore the test
  based on definition of CONFIG_SLUB_DEBUG_ON is unreliable.

This patch fixes the problem by removing the test
"!defined(CONFIG_SLUB_DEBUG_ON)". Therefore, duplicate names are never
checked if the SLUB allocator is used.

Note to stable kernel maintainers: when backporint this patch, please
backport also the patch 3e374919b3.

Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org	# 3.6+
Signed-off-by: Pekka Enberg <penberg@kernel.org>
This commit is contained in:
Mikulas Patocka 2014-03-04 17:13:47 -05:00 committed by Pekka Enberg
parent 4b660a7f5c
commit 694617474e

View file

@ -55,7 +55,7 @@ static int kmem_cache_sanity_check(const char *name, size_t size)
continue;
}
#if !defined(CONFIG_SLUB) || !defined(CONFIG_SLUB_DEBUG_ON)
#if !defined(CONFIG_SLUB)
if (!strcmp(s->name, name)) {
pr_err("%s (%s): Cache name already exists.\n",
__func__, name);