diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index a3098046250bfa5999f71f905109f1275f87481f..47868a86ba2bdb15966e8eb396b9a94ee81ac2db 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -144,10 +144,6 @@ enum {
CGRP_RELEASABLE,
/* Control Group requires release notifications to userspace */
CGRP_NOTIFY_ON_RELEASE,
- /*
- * A thread in rmdir() is wating for this cgroup.
- */
- CGRP_WAIT_ON_RMDIR,
/*
* Clone cgroup values when creating a new child cgroup
*/
@@ -411,23 +407,6 @@ int cgroup_task_count(const struct cgroup *cgrp);
/* Return true if cgrp is a descendant of the task's cgroup */
int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task);
-/*
- * When the subsys has to access css and may add permanent refcnt to css,
- * it should take care of racy conditions with rmdir(). Following set of
- * functions, is for stop/restart rmdir if necessary.
- * Because these will call css_get/put, "css" should be alive css.
- *
- * cgroup_exclude_rmdir();
- * ...do some jobs which may access arbitrary empty cgroup
- * cgroup_release_and_wakeup_rmdir();
- *
- * When someone removes a cgroup while cgroup_exclude_rmdir() holds it,
- * it sleeps and cgroup_release_and_wakeup_rmdir() will wake him up.
- */
-
-void cgroup_exclude_rmdir(struct cgroup_subsys_state *css);
-void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css);
-
/*
* Control Group taskset, used to pass around set of tasks to cgroup_subsys
* methods.
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 66204a6f68f3f40d782e90d4b3c60d493e46f64a..c5f6fb28dd0e7badf197af28c9da6dfd8cf97dcb 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -965,33 +965,6 @@ static void cgroup_d_remove_dir(struct dentry *dentry)
remove_dir(dentry);
}
-/*
- * A queue for waiters to do rmdir() cgroup. A tasks will sleep when
- * cgroup->count == 0 && list_empty(&cgroup->children) && subsys has some
- * reference to css->refcnt. In general, this refcnt is expected to goes down
- * to zero, soon.
- *
- * CGRP_WAIT_ON_RMDIR flag is set under cgroup's inode->i_mutex;
- */
-static DECLARE_WAIT_QUEUE_HEAD(cgroup_rmdir_waitq);
-
-static void cgroup_wakeup_rmdir_waiter(struct cgroup *cgrp)
-{
- if (unlikely(test_and_clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags)))
- wake_up_all(&cgroup_rmdir_waitq);
-}
-
-void cgroup_exclude_rmdir(struct cgroup_subsys_state *css)
-{
- css_get(css);
-}
-
-void cgroup_release_and_wakeup_rmdir(struct cgroup_subsys_state *css)
-{
- cgroup_wakeup_rmdir_waiter(css->cgroup);
- css_put(css);
-}
-
/*
* Call with cgroup_mutex held. Drops reference counts on modules, including
* any duplicate ones that parse_cgroupfs_options took. If this function
@@ -1963,12 +1936,6 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
}
synchronize_rcu();
-
- /*
- * wake up rmdir() waiter. the rmdir should fail since the cgroup
- * is no longer empty.
- */
- cgroup_wakeup_rmdir_waiter(cgrp);
out:
if (retval) {
for_each_subsys(root, ss) {
@@ -2138,7 +2105,6 @@ static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
* step 5: success! and cleanup
*/
synchronize_rcu();
- cgroup_wakeup_rmdir_waiter(cgrp);
retval = 0;
out_put_css_set_refs:
if (retval) {
@@ -4058,26 +4024,13 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
struct cgroup_event *event, *tmp;
struct cgroup_subsys *ss;
- /*
- * In general, subsystem has no css->refcnt after pre_destroy(). But
- * in racy cases, subsystem may have to get css->refcnt after
- * pre_destroy() and it makes rmdir return with -EBUSY. This sometimes
- * make rmdir return -EBUSY too often. To avoid that, we use waitqueue
- * for cgroup's rmdir. CGRP_WAIT_ON_RMDIR is for synchronizing rmdir
- * and subsystem's reference count handling. Please see css_get/put
- * and css_tryget() and cgroup_wakeup_rmdir_waiter() implementation.
- */
- set_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
-
/* the vfs holds both inode->i_mutex already */
mutex_lock(&cgroup_mutex);
parent = cgrp->parent;
if (atomic_read(&cgrp->count) || !list_empty(&cgrp->children)) {
- clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
mutex_unlock(&cgroup_mutex);
return -EBUSY;
}
- prepare_to_wait(&cgroup_rmdir_waitq, &wait, TASK_INTERRUPTIBLE);
/*
* Block new css_tryget() by deactivating refcnt and mark @cgrp
@@ -4114,9 +4067,6 @@ static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry)
for_each_subsys(cgrp->root, ss)
css_put(cgrp->subsys[ss->subsys_id]);
- finish_wait(&cgroup_rmdir_waitq, &wait);
- clear_bit(CGRP_WAIT_ON_RMDIR, &cgrp->flags);
-
raw_spin_lock(&release_list_lock);
if (!list_empty(&cgrp->release_list))
list_del_init(&cgrp->release_list);
@@ -4864,7 +4814,6 @@ void __css_put(struct cgroup_subsys_state *css)
set_bit(CGRP_RELEASABLE, &cgrp->flags);
check_for_release(cgrp);
}
- cgroup_wakeup_rmdir_waiter(cgrp);
break;
case 0:
schedule_work(&css->dput_work);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 37c356646544396a61ae6887b483c975b05b6f31..930edfaa51875d26c59116d04dd4e40baa5c9b2c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2681,13 +2681,6 @@ static int mem_cgroup_move_account(struct page *page,
/* caller should have done css_get */
pc->mem_cgroup = to;
mem_cgroup_charge_statistics(to, anon, nr_pages);
- /*
- * We charges against "to" which may not have any tasks. Then, "to"
- * can be under rmdir(). But in current implementation, caller of
- * this function is just force_empty() and move charge, so it's
- * guaranteed that "to" is never removed. So, we don't check rmdir
- * status here.
- */
move_unlock_mem_cgroup(from, &flags);
ret = 0;
unlock:
@@ -2893,7 +2886,6 @@ __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
return;
if (!memcg)
return;
- cgroup_exclude_rmdir(&memcg->css);
__mem_cgroup_commit_charge(memcg, page, 1, ctype, true);
/*
@@ -2907,12 +2899,6 @@ __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
swp_entry_t ent = {.val = page_private(page)};
mem_cgroup_uncharge_swap(ent);
}
- /*
- * At swapin, we may charge account against cgroup which has no tasks.
- * So, rmdir()->pre_destroy() can be called while we do this charge.
- * In that case, we need to call pre_destroy() again. check it here.
- */
- cgroup_release_and_wakeup_rmdir(&memcg->css);
}
void mem_cgroup_commit_charge_swapin(struct page *page,
@@ -3360,8 +3346,7 @@ void mem_cgroup_end_migration(struct mem_cgroup *memcg,
if (!memcg)
return;
- /* blocks rmdir() */
- cgroup_exclude_rmdir(&memcg->css);
+
if (!migration_ok) {
used = oldpage;
unused = newpage;
@@ -3395,13 +3380,6 @@ void mem_cgroup_end_migration(struct mem_cgroup *memcg,
*/
if (anon)
mem_cgroup_uncharge_page(used);
- /*
- * At migration, we may charge account against cgroup which has no
- * tasks.
- * So, rmdir()->pre_destroy() can be called while we do this charge.
- * In that case, we need to call pre_destroy() again. check it here.
- */
- cgroup_release_and_wakeup_rmdir(&memcg->css);
}
/*