Messages in this thread Patch in this message | | | Date | Tue, 3 Jun 2014 12:04:38 +0800 | From | Li Zefan <> | Subject | [PATCH 1/3] cgroup: don't destroy the default root |
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The default root is allocated and initialized at boot, so we shouldn't destroy the default root when it's umounted, otherwise it will lead to disaster.
Signed-off-by: Li Zefan <lizefan@huawei.com> --- kernel/cgroup.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index a5f75ac..f73fe48 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1027,12 +1027,14 @@ static umode_t cgroup_file_mode(const struct cftype *cft) static void cgroup_get(struct cgroup *cgrp) { WARN_ON_ONCE(cgroup_is_dead(cgrp)); - css_get(&cgrp->self); + if (!(cgrp->self.flags & CSS_NO_REF)) + css_get(&cgrp->self); } static void cgroup_put(struct cgroup *cgrp) { - css_put(&cgrp->self); + if (!(cgrp->self.flags & CSS_NO_REF)) + css_put(&cgrp->self); } /** @@ -1781,10 +1783,12 @@ static void cgroup_kill_sb(struct super_block *sb) * This prevents new mounts by disabling percpu_ref_tryget_live(). * cgroup_mount() may wait for @root's release. */ - if (css_has_online_children(&root->cgrp.self)) + if (css_has_online_children(&root->cgrp.self)) { cgroup_put(&root->cgrp); - else - percpu_ref_kill(&root->cgrp.self.refcnt); + } else { + if (root != &cgrp_dfl_root) + percpu_ref_kill(&root->cgrp.self.refcnt); + } kernfs_kill_sb(sb); } -- 1.8.0.2
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