Re: [PATCH 1/4] mm/mempolicy: kernel_migrate_pages: simplify the usage of put_task_struct()

[Gregory Price <gourry@gourry.net>]

On Sun, May 24, 2026 at 06:57:59PM +0200, Oleg Nesterov wrote:
> kernel_migrate_pages() calls put_task_struct() twice; this complicates the
> code. Move put_task_struct() to the unified exit path. This also allows us
> to move the "out_put" label up and avoid another goto.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Reviewed-by: Gregory Price <gourry@gourry.net>

> ---
>  mm/mempolicy.c | 11 +++--------
>  1 file changed, 3 insertions(+), 8 deletions(-)
> 
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 4e4421b22b59..4326dff16aa6 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1922,25 +1922,20 @@ static int kernel_migrate_pages(pid_t pid, unsigned long maxnode,
>  		goto out_put;
>  
>  	mm = get_task_mm(task);
> -	put_task_struct(task);
> -
>  	if (!mm) {
>  		err = -EINVAL;
> -		goto out;
> +		goto out_put;
>  	}
>  
>  	err = do_migrate_pages(mm, old, new,
>  		capable(CAP_SYS_NICE) ? MPOL_MF_MOVE_ALL : MPOL_MF_MOVE);
>  
>  	mmput(mm);
> +out_put:
> +	put_task_struct(task);
>  out:
>  	NODEMASK_SCRATCH_FREE(scratch);
> -
>  	return err;
> -
> -out_put:
> -	put_task_struct(task);
> -	goto out;
>  }
>  
>  SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
> -- 
> 2.52.0
>