Re: [PATCH v2 6/8] fs: convert process/thread iterators to for_each_*_rculock

[Lorenzo Stoakes (ARM)]

On Mon, Sep 07, 2026 at 04:13:32PM +0800, Ye Liu wrote:
> From: Ye Liu <liuye@xxxxxxxxxx>
>
> Replace the manual rcu_read_lock()/rcu_read_unlock() pairs combined
> with for_each_process() and for_each_process_thread() loops in fs/
> 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@xxxxxxxxxx>
> Acked-by: Michal Hocko <mhocko@xxxxxxxx>

LGTM so:

Reviewed-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>

> ---
> Changes in v2:
>   - Rename *_rcu to *_rculock
>  fs/proc/base.c        | 4 +---
>  fs/resctrl/rdtgroup.c | 8 ++------
>  2 files changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 6a39de424f62..3de4f4557e4c 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -1160,8 +1160,7 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
>  	if (mm) {
>  		struct task_struct *p;
>
> -		rcu_read_lock();
> -		for_each_process(p) {
> +		for_each_process_rculock(p) {
>  			if (same_thread_group(task, p))
>  				continue;
>
> @@ -1177,7 +1176,6 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
>  			}
>  			task_unlock(p);
>  		}
> -		rcu_read_unlock();
>  		mmdrop(mm);
>  	}
>  err_unlock:
> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index 5dcbb0a964e8..b14df8b23f1a 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -709,14 +709,12 @@ int rdtgroup_tasks_assigned(struct rdtgroup *r)
>
>  	lockdep_assert_held(&rdtgroup_mutex);
>
> -	rcu_read_lock();
> -	for_each_process_thread(p, t) {
> +	for_each_process_thread_rculock(p, t) {
>  		if (is_closid_match(t, r) || is_rmid_match(t, r)) {
>  			ret = 1;
>  			break;
>  		}
>  	}
> -	rcu_read_unlock();
>
>  	return ret;
>  }
> @@ -826,15 +824,13 @@ static void show_rdt_tasks(struct rdtgroup *r, struct seq_file *s)
>  	struct task_struct *p, *t;
>  	pid_t pid;
>
> -	rcu_read_lock();
> -	for_each_process_thread(p, t) {
> +	for_each_process_thread_rculock(p, t) {
>  		if (is_closid_match(t, r) || is_rmid_match(t, r)) {
>  			pid = task_pid_vnr(t);
>  			if (pid)
>  				seq_printf(s, "%d\n", pid);
>  		}
>  	}
> -	rcu_read_unlock();
>  }
>
>  static int rdtgroup_tasks_show(struct kernfs_open_file *of,
> --
> 2.25.1
>

--
Cheers, Lorenzo