Re: [PATCH 3/8] mm: remove MPOL_MF_STATS

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

> Mapping statistics in a NUMA environment is now computed using the
> generic walk_page_range() logic.  Remove the old/equivalent
> functionality.
> 
> Signed-off-by: Stephen Wilson <wilsons@start.ca>
> ---
>  mm/mempolicy.c |   10 ++++++----
>  1 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index dfe27e3..63c0d69 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -99,7 +99,6 @@
>  /* Internal flags */
>  #define MPOL_MF_DISCONTIG_OK (MPOL_MF_INTERNAL << 0)	/* Skip checks for continuous vmas */
>  #define MPOL_MF_INVERT (MPOL_MF_INTERNAL << 1)		/* Invert check for nodemask */
> -#define MPOL_MF_STATS (MPOL_MF_INTERNAL << 2)		/* Gather statistics */
>  
>  static struct kmem_cache *policy_cache;
>  static struct kmem_cache *sn_cache;
> @@ -492,9 +491,7 @@ static int check_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
>  		if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
>  			continue;
>  
> -		if (flags & MPOL_MF_STATS)
> -			gather_stats(page, private, pte_dirty(*pte));
> -		else if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
> +		if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
>  			migrate_page_add(page, private, flags);
>  		else
>  			break;

This hunk looks good to me.


> @@ -2572,6 +2569,7 @@ static int gather_pte_stats(pte_t *pte, unsigned long addr,
>  		unsigned long pte_size, struct mm_walk *walk)
>  {
>  	struct page *page;
> +	int nid;
>  
>  	if (pte_none(*pte))
>  		return 0;
> @@ -2580,6 +2578,10 @@ static int gather_pte_stats(pte_t *pte, unsigned long addr,
>  	if (!page)
>  		return 0;
>  
> +	nid = page_to_nid(page);
> +	if (!node_isset(nid, node_states[N_HIGH_MEMORY]))
> +		return 0;
> +
>  	gather_stats(page, walk->private, pte_dirty(*pte));
>  	return 0;

However this hunk should be moved into patch [2/8]. because 1) keeping
bisectability 2) The description says "Remove the old/equivalent
functionality." but it added new functionality.