slab_common: fix the check for duplicate slab names

Mikulas Patocka · penberg · commit 694617474e33 · 2014-05-24T00:25:46.000+03:00
The patch 3e37491 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 3e37491. 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>
diff --git a/mm/slab_common.c b/mm/slab_common.c
@@ -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);

Original file line number	Diff line number	Diff line change
`@@ -55,7 +55,7 @@ static int kmem_cache_sanity_check(const char *name, size_t size)`
`55`	`55`	`continue;`
`56`	`56`	`}`
`57`	`57`
`58`		`-#if !defined(CONFIG_SLUB) \|\| !defined(CONFIG_SLUB_DEBUG_ON)`
	`58`	`+#if !defined(CONFIG_SLUB)`
`59`	`59`	`if (!strcmp(s->name, name)) {`
`60`	`60`	`pr_err("%s (%s): Cache name already exists.\n",`
`61`	`61`	`__func__, name);`