Re: [PATCH] Problems with RAID 4/5/6 and kmem_cache

[Christoph Lameter <cl@linux.com>]

On Thu, 19 Sep 2013, Jonathan Brassow wrote:

> 4) kmem_cache_create(name="foo-a")
> - This FAILS because kmem_cache_sanity_check colides with the existing
>   name ("foo-a") associated with the non-removed cache.

That should not happen. breakage you see will result. Oh. I see the move
to common code resulted in the SLAB checks being used for SLUB.

The following patch should fix this.

Subject: slab_common: Do not check for duplicate slab names

SLUB can alias multiple slab kmem_create_requests to one slab cache
to save memory and increase the cache hotness. As a result the name
of the slab can be stale. Only check the name for duplicates if we are
in debug mode where we do not merge multiple caches.

Signed-off-by: Christoph Lameter <cl@linux.com>

Index: linux/mm/slab_common.c
===================================================================
--- linux.orig/mm/slab_common.c	2013-09-20 11:49:13.052208294 -0500
+++ linux/mm/slab_common.c	2013-09-21 16:55:23.097131481 -0500
@@ -56,6 +56,7 @@
 			continue;
 		}

+#if !defined(CONFIG_SLUB) || !defined(CONFIG_SLUB_DEBUG_ON)
 		/*
 		 * For simplicity, we won't check this in the list of memcg
 		 * caches. We have control over memcg naming, and if there
@@ -69,6 +70,7 @@
 			s = NULL;
 			return -EINVAL;
 		}
+#endif
 	}

 	WARN_ON(strchr(name, ' '));	/* It confuses parsers */

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