Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-11 06:31:49 +00:00
Code Issues Packages Projects Releases Wiki Activity

cgroup: make sure parent won't be destroyed before its children

Browse Source 
Suppose we rmdir a cgroup and there're still css refs, this cgroup won't
be freed. Then we rmdir the parent cgroup, and the parent is freed
immediately due to css ref draining to 0. Now it would be a disaster if
the still-alive child cgroup tries to access its parent.

Make sure this won't happen.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Li Zefan 2013-04-08 14:35:02 +08:00 committed by Tejun Heo
parent 84cfb6ab48
commit 415cf07a1c
1 changed files with 10 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
kernel/cgroup.c
View File

@ -875,6 +875,13 @@ static void cgroup_free_fn(struct work_struct *work)
cgrp->root->number_of_cgroups--;
mutex_unlock(&cgroup_mutex);
/*
* We get a ref to the parent's dentry, and put the ref when
* this cgroup is being freed, so it's guaranteed that the
* parent won't be destroyed before its children.
*/
dput(cgrp->parent->dentry);
/*
* Drop the active superblock reference that we took when we
* created the cgroup
@ -4164,6 +4171,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
for_each_subsys(root, ss)
dget(dentry);
/* hold a ref to the parent's dentry */
dget(parent->dentry);
/* creation succeeded, notify subsystems */
for_each_subsys(root, ss) {
err = online_css(ss, cgrp);