[Devel] [PATCH VZ10] cgroup: use __cset_cgroup_from_root in VZ slice join/leave

[Pavel Tikhomirov]

On 4/2/26 09:36, Vasileios Almpanis wrote:
> cset_cgroup_from_root() uses lockdep_assert_held(&css_set_lock), but
> cgroup_join_vz_slice() and cgroup_leave_vz_slice() only stabilize the VE
> nsproxy/cgroup_ns root_cset via rcu_dereference_protected().
> For the default hierarchy the result is just cset->dfl_cgrp, which is
> safe to read without css_set_lock (see current_cgns_cgroup_dfl()).
> Call __cset_cgroup_from_root() instead so lockdep matches the actual
> locking rules.
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-128317
> 
> Signed-off-by: Vasileios Almpanis <vasileios.almpanis at virtuozzo.com>

Reviewed-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>

> 
> Feature: ve: ve generic structures
> ---
>  kernel/cgroup/cgroup.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
> index 376c9bbd1c41..932414b882dd 100644
> --- a/kernel/cgroup/cgroup.c
> +++ b/kernel/cgroup/cgroup.c
> @@ -2243,7 +2243,7 @@ int cgroup_join_vz_slice(struct ve_struct *ve)
>  	int ret;
>  
>  	cset = rcu_dereference_protected(ve->ve_nsproxy, 1)->cgroup_ns->root_cset;
> -	cgrp = cset_cgroup_from_root(cset, &cgrp_dfl_root);
> +	cgrp = __cset_cgroup_from_root(cset, &cgrp_dfl_root);
>  
>  	if (!is_virtualized_cgroup(cgrp) ||
>  	    !test_bit(CGRP_VE_ROOT, &cgrp->flags))
> @@ -2278,7 +2278,7 @@ int cgroup_leave_vz_slice(struct ve_struct *ve)
>  	struct cgroup *cgrp;
>  
>  	cset = rcu_dereference_protected(ve->ve_nsproxy, 1)->cgroup_ns->root_cset;
> -	cgrp = cset_cgroup_from_root(cset, &cgrp_dfl_root);
> +	cgrp = __cset_cgroup_from_root(cset, &cgrp_dfl_root);
>  
>  	if (!is_virtualized_cgroup(cgrp) ||
>  	    !test_bit(CGRP_VE_ROOT, &cgrp->flags))

-- 
Best regards, Pavel Tikhomirov
Senior Software Developer, Virtuozzo.