[PATCH v2 5/8] kernel: convert process/thread iterators to for_each_*_rculock

[Gregory Price]

On Mon, Sep 07, 2026 at 04:13:31PM +0800, Ye Liu wrote:
> From: Ye Liu <liuye at kylinos.cn>
> 
> Replace the manual rcu_read_lock()/rcu_read_unlock() and guard(rcu)
> pairs combined with for_each_process(), for_each_thread() and
> for_each_process_thread() loops across kernel/ with the
> for_each_*_rculock() macros, which scope the RCU read lock to the
> loop body via scoped_guard(rcu).
> 
> No functional change.
> 
> Signed-off-by: Ye Liu <liuye at kylinos.cn>
> Acked-by: Michal Hocko <mhocko at suse.com>

Question below

> diff --git a/kernel/hung_task.c b/kernel/hung_task.c
> index 6fcc94ce4ca9..73a5ad3be9a8 100644
> --- a/kernel/hung_task.c
> +++ b/kernel/hung_task.c
> @@ -315,13 +315,12 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
>  		return;
>  
>  	this_round_count = 0;
> -	rcu_read_lock();
> -	for_each_process_thread(g, t) {
> +	for_each_process_thread_rculock(g, t) {
>  		if (!max_count--)
> -			goto unlock;
> +			goto out;
... snip ...
> - unlock:
> -	rcu_read_unlock();
> -
> +out:
>  	if (!this_round_count)
>  		return;
>  

The sunken rcu_read_lock()/unlock() + scoped_guard usage makes this goto
at a minimum very confusing, if not actually broken.

Are we sure this isn't broken as-written? Generally we don't mix cleanup
and goto for exactly this reason.

~Gregory