The patch below seems to reference a patch that showed up in 3.11-rc1,
so why would it be relevant for the 3.10 or other stable kernels?
thanks,
greg k-h
> commit: fc76df706123602214da494ba98bccea83e2cfff
> From: Tejun Heo <tj@xxxxxxxxxx>
> Date: Tue, 25 Jun 2013 11:53:37 -0700
> Subject: cgroup: reserve ID 0 for dummy_root and 1 for unified hierarchy
>
> Before 1a57423166 ("cgroup: make hierarchy_id use cyclic idr"),
> hierarchy IDs were allocated from 0. As the dummy hierarchy was
> always the one first initialized, it got assigned 0 and all other
> hierarchies from 1. The patch accidentally changed the minimum
> useable ID to 2.
>
> Let's restore ID 0 for dummy_root and while at it reserve 1 for
> unified hierarchy.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Acked-by: Li Zefan <lizefan@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> kernel/cgroup.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index cef6881..f9c99ab 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -1425,14 +1425,15 @@ static void init_cgroup_root(struct cgroupfs_root *root)
> init_cgroup_housekeeping(cgrp);
> }
>
> -static int cgroup_init_root_id(struct cgroupfs_root *root)
> +static int cgroup_init_root_id(struct cgroupfs_root *root, int start, int end)
> {
> int id;
>
> lockdep_assert_held(&cgroup_mutex);
> lockdep_assert_held(&cgroup_root_mutex);
>
> - id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 2, 0, GFP_KERNEL);
> + id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, start, end,
> + GFP_KERNEL);
> if (id < 0)
> return id;
>
> @@ -1635,7 +1636,8 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type,
> if (ret)
> goto unlock_drop;
>
> - ret = cgroup_init_root_id(root);
> + /* ID 0 is reserved for dummy root, 1 for unified hierarchy */
> + ret = cgroup_init_root_id(root, 2, 0);
> if (ret)
> goto unlock_drop;
>
> @@ -4898,7 +4900,7 @@ int __init cgroup_init(void)
> key = css_set_hash(init_css_set.subsys);
> hash_add(css_set_table, &init_css_set.hlist, key);
>
> - BUG_ON(cgroup_init_root_id(&cgroup_dummy_root));
> + BUG_ON(cgroup_init_root_id(&cgroup_dummy_root, 0, 1));
>
> mutex_unlock(&cgroup_root_mutex);
> mutex_unlock(&cgroup_mutex);
> --
> 1.7.10.4
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