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cgroup: fix idr leak for the first cgroup root

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The valid cgroup hierarchy ID range includes 0, so we can't filter for
positive numbers when freeing it, or it'll leak the first ID.  No big
deal, just disruptive when reading the code.

The ID is freed during error handling and when the reference count hits
zero, so the double-free test is not necessary; remove it.

Link: http://lkml.kernel.org/r/20160617162359.GB19084@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Johannes Weiner 2016-07-26 15:26:58 -07:00 committed by Linus Torvalds
parent 25843c2b21
commit 1fe4d021ac
1 changed files with 1 additions and 7 deletions
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8
kernel/cgroup.c
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@ -1160,18 +1160,12 @@ static void cgroup_exit_root_id(struct cgroup_root *root)
{
lockdep_assert_held(&cgroup_mutex);
if (root->hierarchy_id) {
idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
root->hierarchy_id = 0;
}
idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
}
static void cgroup_free_root(struct cgroup_root *root)
{
if (root) {
/* hierarchy ID should already have been released */
WARN_ON_ONCE(root->hierarchy_id);
idr_destroy(&root->cgroup_idr);
kfree(root);
}