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authorTejun Heo <tj@kernel.org>2017-02-22 15:41:39 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-22 16:41:27 -0800
commit1663f26df3df7df3720306ca67f5ea8296d68fa1 (patch)
tree6ad80b7ccc7d093c0a14532affa376452f523afe /mm/slub.c
parent17cc4dfeda97636d67e83de8cd41940b65a93bc7 (diff)
downloadop-kernel-dev-1663f26df3df7df3720306ca67f5ea8296d68fa1.zip
op-kernel-dev-1663f26df3df7df3720306ca67f5ea8296d68fa1.tar.gz
slub: make sysfs directories for memcg sub-caches optional
SLUB creates a per-cache directory under /sys/kernel/slab which hosts a bunch of debug files. Usually, there aren't that many caches on a system and this doesn't really matter; however, if memcg is in use, each cache can have per-cgroup sub-caches. SLUB creates the same directories for these sub-caches under /sys/kernel/slab/$CACHE/cgroup. Unfortunately, because there can be a lot of cgroups, active or draining, the product of the numbers of caches, cgroups and files in each directory can reach a very high number - hundreds of thousands is commonplace. Millions and beyond aren't difficult to reach either. What's under /sys/kernel/slab is primarily for debugging and the information and control on the a root cache already cover its sub-caches. While having a separate directory for each sub-cache can be helpful for development, it doesn't make much sense to pay this amount of overhead by default. This patch introduces a boot parameter slub_memcg_sysfs which determines whether to create sysfs directories for per-memcg sub-caches. It also adds CONFIG_SLUB_MEMCG_SYSFS_ON which determines the boot parameter's default value and defaults to 0. [akpm@linux-foundation.org: kset_unregister(NULL) is legal] Link: http://lkml.kernel.org/r/20170204145203.GB26958@mtj.duckdns.org Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slub.c')
-rw-r--r--mm/slub.c26
1 files changed, 24 insertions, 2 deletions
diff --git a/mm/slub.c b/mm/slub.c
index af38aaa..7f4bc70 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -4708,6 +4708,22 @@ enum slab_stat_type {
#define SO_OBJECTS (1 << SL_OBJECTS)
#define SO_TOTAL (1 << SL_TOTAL)
+#ifdef CONFIG_MEMCG
+static bool memcg_sysfs_enabled = IS_ENABLED(CONFIG_SLUB_MEMCG_SYSFS_ON);
+
+static int __init setup_slub_memcg_sysfs(char *str)
+{
+ int v;
+
+ if (get_option(&str, &v) > 0)
+ memcg_sysfs_enabled = v;
+
+ return 1;
+}
+
+__setup("slub_memcg_sysfs=", setup_slub_memcg_sysfs);
+#endif
+
static ssize_t show_slab_objects(struct kmem_cache *s,
char *buf, unsigned long flags)
{
@@ -5611,8 +5627,14 @@ static int sysfs_slab_add(struct kmem_cache *s)
{
int err;
const char *name;
+ struct kset *kset = cache_kset(s);
int unmergeable = slab_unmergeable(s);
+ if (!kset) {
+ kobject_init(&s->kobj, &slab_ktype);
+ return 0;
+ }
+
if (unmergeable) {
/*
* Slabcache can never be merged so we can use the name proper.
@@ -5629,7 +5651,7 @@ static int sysfs_slab_add(struct kmem_cache *s)
name = create_unique_id(s);
}
- s->kobj.kset = cache_kset(s);
+ s->kobj.kset = kset;
err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
if (err)
goto out;
@@ -5639,7 +5661,7 @@ static int sysfs_slab_add(struct kmem_cache *s)
goto out_del_kobj;
#ifdef CONFIG_MEMCG
- if (is_root_cache(s)) {
+ if (is_root_cache(s) && memcg_sysfs_enabled) {
s->memcg_kset = kset_create_and_add("cgroup", NULL, &s->kobj);
if (!s->memcg_kset) {
err = -ENOMEM;
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