Re: [PATCH 4/8] mm/memory-failure: convert process iterator to for_each_process_rcu

[Michal Hocko]

On Fri 04-09-26 16:29:56, Ye Liu wrote:
> From: Ye Liu <liuye@xxxxxxxxxx>
> 
> Replace the manual rcu_read_lock()/rcu_read_unlock() pairs combined
> with for_each_process() loop in mm/memory-failure.c with
> for_each_process_rcu().
> 
> No functional change.
> 
> Signed-off-by: Ye Liu <liuye@xxxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxxx>

> ---
>  mm/memory-failure.c | 16 ++++------------
>  1 file changed, 4 insertions(+), 12 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index a8b03e2920ba..63a2ff08ee33 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -555,8 +555,7 @@ static void collect_procs_anon(const struct folio *folio,
>  		return;
>  
>  	pgoff = page_pgoff(folio, page);
> -	rcu_read_lock();
> -	for_each_process(tsk) {
> +	for_each_process_rcu(tsk) {
>  		struct vm_area_struct *vma;
>  		struct anon_vma_chain *vmac;
>  		struct task_struct *t = task_early_kill(tsk, force_early);
> @@ -572,7 +571,6 @@ static void collect_procs_anon(const struct folio *folio,
>  			add_to_kill_anon_file(t, page, vma, to_kill, addr);
>  		}
>  	}
> -	rcu_read_unlock();
>  	anon_vma_unlock_read(av);
>  }
>  
> @@ -589,9 +587,8 @@ static void collect_procs_file(const struct folio *folio,
>  	pgoff_t pgoff;
>  
>  	i_mmap_lock_read(mapping);
> -	rcu_read_lock();
>  	pgoff = page_pgoff(folio, page);
> -	for_each_process(tsk) {
> +	for_each_process_rcu(tsk) {
>  		struct task_struct *t = task_early_kill(tsk, force_early);
>  		unsigned long addr;
>  
> @@ -611,7 +608,6 @@ static void collect_procs_file(const struct folio *folio,
>  			add_to_kill_anon_file(t, page, vma, to_kill, addr);
>  		}
>  	}
> -	rcu_read_unlock();
>  	i_mmap_unlock_read(mapping);
>  }
>  
> @@ -635,8 +631,7 @@ static void collect_procs_fsdax(const struct page *page,
>  	struct task_struct *tsk;
>  
>  	i_mmap_lock_read(mapping);
> -	rcu_read_lock();
> -	for_each_process(tsk) {
> +	for_each_process_rcu(tsk) {
>  		struct task_struct *t = tsk;
>  
>  		/*
> @@ -653,7 +648,6 @@ static void collect_procs_fsdax(const struct page *page,
>  				add_to_kill_fsdax(t, page, vma, to_kill, pgoff);
>  		}
>  	}
> -	rcu_read_unlock();
>  	i_mmap_unlock_read(mapping);
>  }
>  #endif /* CONFIG_FS_DAX */
> @@ -2288,8 +2282,7 @@ static void collect_procs_pfn(struct pfn_address_space *pfn_space,
>  	struct address_space *mapping = pfn_space->mapping;
>  
>  	i_mmap_lock_read(mapping);
> -	rcu_read_lock();
> -	for_each_process(tsk) {
> +	for_each_process_rcu(tsk) {
>  		struct task_struct *t = tsk;
>  
>  		t = task_early_kill(tsk, true);
> @@ -2303,7 +2296,6 @@ static void collect_procs_pfn(struct pfn_address_space *pfn_space,
>  				add_to_kill_pgoff(t, vma, to_kill, pgoff);
>  		}
>  	}
> -	rcu_read_unlock();
>  	i_mmap_unlock_read(mapping);
>  }
>  
> -- 
> 2.25.1
> 

-- 
Michal Hocko
SUSE Labs