[PATCH v2 2/2] SLUB: Mark merged slab caches in /proc/slabinfo

Pekka Enberg
2010-09-14T18:48:35Z

SLUB uses the name of the first slab cache for all merged slab caches. To make
the output of /proc/slabinfo more obvious, append the name of each merged slab
cache to s->name.

An example output of /proc/slabinfo with this patch looks like this:

kmalloc-8192 544 544 8192 4 8 : tunables 0
kmalloc-4096+names_cache+biovec-256+sgpool-128+ecryptfs_headers
kmalloc-2048+biovec-128+sgpool-64 400 416 2048 16 8
kmalloc-1024+biovec-64+sgpool-32 436 496 1024 16 4 :
kmalloc-512+task_xstate+skbuff_fclone_cache+sgpool-16 1060 10
kmalloc-256+mnt_cache+skbuff_head_cache+biovec-16+sgpool-8+arp_ [ snip ]
kmalloc-128+pid+bip-1+eventpoll_epi+request_sock_TCP+ip_mrt_cac
kmalloc-64+fs_cache+biovec-4+blkdev_ioc+inet_peer_cache+tcp_bin
kmalloc-32+ip_fib_alias+dnotify_struct+inotify_event_private_da
kmalloc-16+biovec-1+ecryptfs_file_cache+dm_rq_clone_bio_info+dm
kmalloc-8 5119 5120 8 512 1 : tunables 0
kmalloc-192+cred_jar+key_jar+filp+bip-4+bio-0+request_sock_TCPv
kmalloc-96 924 1008 96 42 1 : tunables 0
kmem_cache_node 128 128 64 64 1 : tunables 0

Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
---
mm/slub.c | 37 +++++++++++++++++++++++++++++++++++++
1 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index a31c033..77e4438 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3161,6 +3161,40 @@ void __init kmem_cache_init_late(void)
}

/*
+ * This limit is part of /proc/slabinfo ABI. It has never been enforced by the
+ * kernel but userspace programs such as "slabtop" expect it.
+ */
+#define MAX_SLAB_NAME_LEN 63
+
+static int kmem_merge_names(struct kmem_cache *s, const char *name)
+{
+ size_t new_size;
+ char *new_name;
+
+ if (strlen(s->name) >= MAX_SLAB_NAME_LEN)
+ return 0;
+
+ /* Don't append name to merged name more than once */
+ if (strstr(s->name, name))
+ return 0;
+
+ new_size = strlen(s->name) + strlen(name) + 2;
+ if (new_size > (MAX_SLAB_NAME_LEN + 1))
+ new_size = MAX_SLAB_NAME_LEN + 1; /* NULL terminate */
+
+ new_name = kmalloc(new_size, GFP_KERNEL);
+ if (!new_name)
+ return -ENOMEM;
+
+ snprintf(new_name, new_size, "%s+%s", s->name, name);
+
+ kfree(s->name);
+ s->name = new_name;
+
+ return 0;
+}
+
+/*
* Find a mergeable slab cache
*/
static int slab_unmergeable(struct kmem_cache *s)
@@ -3233,6 +3267,9 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size,
down_write(&slub_lock);
s = find_mergeable(size, align, flags, name, ctor);
if (s) {
+ if (kmem_merge_names(s, name))
+ goto err;
+
s->refcount++;
/*
* Adjust the object sizes so that we clear
--
1.6.3.3