Re: [PATCH v2 3/8] mm/ksm: convert process iterator to for_each_process_rculock

[Lorenzo Stoakes (ARM)]

On Mon, Sep 07, 2026 at 04:13:29PM +0800, Ye Liu wrote:
> From: Ye Liu <liuye@xxxxxxxxxx>
>
> Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
> with for_each_process() loop in mm/ksm.c with for_each_process_rculock(),
> which scopes 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>
> Reviewed-by: SJ Park <sj@xxxxxxxxxx>

LGTM so:

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

> ---
> Changes in v2:
>   - Rename *_rcu to *_rculock
>  mm/ksm.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 49d48d1e0998..69d30e80a090 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -3280,8 +3280,7 @@ void collect_procs_ksm(const struct folio *folio, const struct page *page,
>  		struct anon_vma *av = rmap_item->anon_vma;
>
>  		anon_vma_lock_read(av);
> -		rcu_read_lock();
> -		for_each_process(tsk) {
> +		for_each_process_rculock(tsk) {
>  			struct anon_vma_chain *vmac;
>  			const unsigned long addr = rmap_item->address & PAGE_MASK;
>  			const unsigned long index = rmap_item->linear_page_index;
> @@ -3298,7 +3297,6 @@ void collect_procs_ksm(const struct folio *folio, const struct page *page,
>  				}
>  			}
>  		}
> -		rcu_read_unlock();
>  		anon_vma_unlock_read(av);
>  	}
>  }
> --
> 2.25.1
>

--
Cheers, Lorenzo