Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753123AbbDGNxc (ORCPT ); Tue, 7 Apr 2015 09:53:32 -0400 Received: from mx2.parallels.com ([199.115.105.18]:57981 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751486AbbDGNx3 (ORCPT ); Tue, 7 Apr 2015 09:53:29 -0400 From: Vladimir Davydov To: Andrew Morton CC: Johannes Weiner , Michal Hocko , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , , , Subject: [PATCH -mm] slab: use cgroup ino for naming per memcg caches Date: Tue, 7 Apr 2015 16:53:18 +0300 Message-ID: <1428414798-12932-1-git-send-email-vdavydov@parallels.com> X-Mailer: git-send-email 1.7.10.4 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2409 Lines: 58 The name of a per memcg kmem cache consists of three parts: the global kmem cache name, the cgroup name, and the css id. The latter is used to guarantee cache name uniqueness. Since css ids are opaque to the userspace, in general it is impossible to find a cache's owner cgroup given its name: there might be several same-named cgroups with different parents so that their caches' names will only differ by css id. Looking up the owner cgroup by a cache name, however, could be useful for debugging. For instance, the cache name is dumped to dmesg on a slab allocation failure. Another example is /sys/kernel/slab, which exports some extra info/tunables for SLUB caches referring to them by name. This patch substitutes the css id with cgroup inode number, which, just like css id, is reserved until css free, so that the cache names are still guaranteed to be unique, but, in contrast to css id, it can be easily obtained from userspace. Signed-off-by: Vladimir Davydov --- mm/slab_common.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index 999bb3424d44..e97bf3e04ed7 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -478,7 +478,7 @@ void memcg_create_kmem_cache(struct mem_cgroup *memcg, struct kmem_cache *root_cache) { static char memcg_name_buf[NAME_MAX + 1]; /* protected by slab_mutex */ - struct cgroup_subsys_state *css = mem_cgroup_css(memcg); + struct cgroup *cgroup; struct memcg_cache_array *arr; struct kmem_cache *s = NULL; char *cache_name; @@ -508,9 +508,10 @@ void memcg_create_kmem_cache(struct mem_cgroup *memcg, if (arr->entries[idx]) goto out_unlock; - cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf)); - cache_name = kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name, - css->id, memcg_name_buf); + cgroup = mem_cgroup_css(memcg)->cgroup; + cgroup_name(cgroup, memcg_name_buf, sizeof(memcg_name_buf)); + cache_name = kasprintf(GFP_KERNEL, "%s(%lu:%s)", root_cache->name, + (unsigned long)cgroup_ino(cgroup), memcg_name_buf); if (!cache_name) goto out_unlock; -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/