[PATCH v2 02/10] slub: separate out sysfs_slab_release() from sysfs_slab_remove()

[Tejun Heo]

>From 3b0cdd93b2d9bdea62ea6681e612bdae7a40d883 Mon Sep 17 00:00:00 2001
From: Tejun Heo <t...@kernel.org>
Date: Mon, 23 Jan 2017 17:53:18 -0500

Separate out slub sysfs removal and release, and call the former
earlier from __kmem_cache_shutdown().  There's no reason to defer
sysfs removal through RCU and this will later allow us to remove sysfs
files way earlier during memory cgroup offline instead of release.

v2: Add slab_state >= FULL test to sysfs_slab_release() so that
    kobject_put() is skipped for caches which aren't fully initialized
    as before.  This most likely leaks the kmem_cache on init failure
    as we're skipping the only release path.  Let's fix that up later.

Signed-off-by: Tejun Heo <t...@kernel.org>
Cc: Vladimir Davydov <vdavydov....@gmail.com>
Cc: Christoph Lameter <c...@linux.com>
Cc: Pekka Enberg <penb...@kernel.org>
Cc: David Rientjes <rient...@google.com>
Cc: Joonsoo Kim <iamjoonsoo....@lge.com>
Cc: Andrew Morton <a...@linux-foundation.org>
---
v2 of the patch.  Fixes boot failure reported by the test bot.

Thanks.

 include/linux/slub_def.h |  4 ++--
 mm/slab_common.c         |  2 +-
 mm/slub.c                | 12 ++++++++++--
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 75f56c2..07ef550 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -113,9 +113,9 @@ struct kmem_cache {
 
 #ifdef CONFIG_SYSFS
 #define SLAB_SUPPORTS_SYSFS
-void sysfs_slab_remove(struct kmem_cache *);
+void sysfs_slab_release(struct kmem_cache *);
 #else
-static inline void sysfs_slab_remove(struct kmem_cache *s)
+static inline void sysfs_slab_release(struct kmem_cache *s)
 {
 }
 #endif
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 46ff746..3bc4bb8 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -480,7 +480,7 @@ static void release_caches(struct list_head *release, bool 
need_rcu_barrier)
 
        list_for_each_entry_safe(s, s2, release, list) {
 #ifdef SLAB_SUPPORTS_SYSFS
-               sysfs_slab_remove(s);
+               sysfs_slab_release(s);
 #else
                slab_kmem_cache_release(s);
 #endif
diff --git a/mm/slub.c b/mm/slub.c
index 68b84f9..59ca718 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -214,11 +214,13 @@ enum track_item { TRACK_ALLOC, TRACK_FREE };
 static int sysfs_slab_add(struct kmem_cache *);
 static int sysfs_slab_alias(struct kmem_cache *, const char *);
 static void memcg_propagate_slab_attrs(struct kmem_cache *s);
+static void sysfs_slab_remove(struct kmem_cache *s);
 #else
 static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
 static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
                                                        { return 0; }
 static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { }
+static inline void sysfs_slab_remove(struct kmem_cache *s) { }
 #endif
 
 static inline void stat(const struct kmem_cache *s, enum stat_item si)
@@ -3679,6 +3681,7 @@ int __kmem_cache_shutdown(struct kmem_cache *s)
                if (n->nr_partial || slabs_node(s, node))
                        return 1;
        }
+       sysfs_slab_remove(s);
        return 0;
 }
 
@@ -5629,7 +5632,7 @@ static int sysfs_slab_add(struct kmem_cache *s)
        goto out;
 }
 
-void sysfs_slab_remove(struct kmem_cache *s)
+static void sysfs_slab_remove(struct kmem_cache *s)
 {
        if (slab_state < FULL)
                /*
@@ -5643,7 +5646,12 @@ void sysfs_slab_remove(struct kmem_cache *s)
 #endif
        kobject_uevent(&s->kobj, KOBJ_REMOVE);
        kobject_del(&s->kobj);
-       kobject_put(&s->kobj);
+}
+
+void sysfs_slab_release(struct kmem_cache *s)
+{
+       if (slab_state >= FULL)
+               kobject_put(&s->kobj);
 }
 
 /*
-- 
2.9.3