We previously assumed 'parent' could be null,
so null pointer judgment should be added.

Signed-off-by: Shida Zhang <zhangshida@kylinos.cn>
---
 kernel/cgroup/cgroup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index adb820e98f24..7f230b0ab644 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -5701,7 +5701,8 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
 	}
 	spin_unlock_irq(&css_set_lock);
 
-	cgroup1_check_for_release(parent);
+	if (parent)
+		cgroup1_check_for_release(parent);
 
 	cgroup_bpf_offline(cgrp);
 
-- 
2.25.1

On Tue, May 17, 2022 at 03:31:06PM +0800, Shida Zhang wrote:
> We previously assumed 'parent' could be null,
> so null pointer judgment should be added.
> 
> Signed-off-by: Shida Zhang <zhangshida@kylinos.cn>
> ---
>  kernel/cgroup/cgroup.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
> index adb820e98f24..7f230b0ab644 100644
> --- a/kernel/cgroup/cgroup.c
> +++ b/kernel/cgroup/cgroup.c
> @@ -5701,7 +5701,8 @@ static int cgroup_destroy_locked(struct cgroup *cgrp)
>  	}
>  	spin_unlock_irq(&css_set_lock);
>  
> -	cgroup1_check_for_release(parent);
> +	if (parent)
> +		cgroup1_check_for_release(parent);

The function is never called for a root cgroup. The parent check up above in
the same function is superflous. So, maybe remove that?

Thanks.

-- 
tejun

Tejun Heo <tj@kernel.org> 于2022年5月18日周三 01:07写道：
>
> The function is never called for a root cgroup. The parent check up above in
> the same function is superflous. So, maybe remove that?
>
> Thanks.
>
> --
> tejun

Thanks. I will remake a patch based on this.


--
Stephen