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authorVladimir Davydov <vdavydov@parallels.com>2015-02-12 14:59:26 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-12 18:54:09 -0800
commit01e586598b224d1a427acd8a7afa0b21e879d3a7 (patch)
treecf53ecf130f08a453f3a70963dd3fd6741fee449 /kernel/cgroup.c
parent426589f571f7d6d5ab2ca33ece73164149279ca1 (diff)
cgroup: release css->id after css_free
Currently, we release css->id in css_release_work_fn, right before calling css_free callback, so that when css_free is called, the id may have already been reused for a new cgroup. I am going to use css->id to create unique names for per memcg kmem caches. Since kmem caches are destroyed only on css_free, I need css->id to be freed after css_free was called to avoid name clashes. This patch therefore moves css->id removal to css_free_work_fn. To prevent css_from_id from returning a pointer to a stale css, it makes css_release_work_fn replace the css ptr at css_idr:css->id with NULL. Signed-off-by: Vladimir Davydov <vdavydov@parallels.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Acked-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: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 04cfe8ace520..d5f6ec251fb2 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4373,16 +4373,20 @@ static void css_free_work_fn(struct work_struct *work)
{
struct cgroup_subsys_state *css =
container_of(work, struct cgroup_subsys_state, destroy_work);
+ struct cgroup_subsys *ss = css->ss;
struct cgroup *cgrp = css->cgroup;
percpu_ref_exit(&css->refcnt);
- if (css->ss) {
+ if (ss) {
/* css free path */
+ int id = css->id;
+
if (css->parent)
css_put(css->parent);
- css->ss->css_free(css);
+ ss->css_free(css);
+ cgroup_idr_remove(&ss->css_idr, id);
cgroup_put(cgrp);
} else {
/* cgroup free path */
@@ -4434,7 +4438,7 @@ static void css_release_work_fn(struct work_struct *work)
if (ss) {
/* css release path */
- cgroup_idr_remove(&ss->css_idr, css->id);
+ cgroup_idr_replace(&ss->css_idr, NULL, css->id);
if (ss->css_released)
ss->css_released(css);
} else {