Re: [PATCH] mm: Rename page struct field helpers

[Hugh Dickins]

On Thu, 24 Jan 2013, Mel Gorman wrote:

> The function names page_xchg_last_nid(), page_last_nid() and
> reset_page_last_nid() were judged to be inconsistent so rename them
> to a struct_field_op style pattern. As it looked jarring to have
> reset_page_mapcount() and page_nid_reset_last() beside each other in
> memmap_init_zone(), this patch also renames reset_page_mapcount() to
> page_mapcount_reset(). There are others like init_page_count() but as it
> is used throughout the arch code a rename would likely cause more conflicts
> than it is worth.
> 
> Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxx>

Sorry for not piping up in that earlier thread, but I don't understand
Andrew's reasoning on this: it looks to me like unhelpful churn rather
than improvement (and I suspect your heart is not in it either, Mel).

It's true that sometimes we name things object_verb() and sometimes we
name things verb_object(), but we're always going to be inconsistent on
that, and this patch does not change the fact: page_mapcount_reset()
but set_page_private() (named by one akpm, I believe)?

Being English, I really prefer verb_object(); but there are often
subsystems or cfiles where object_verb() narrows the namespace more
nicely.

xchg_page_last_nid() instead of page_xchg_last_nid(), to match
reset_page_last_nid(): I think that would be a fine change.

page_nid_xchg_last() to exchange page->_last_nid?  You jest, sir!

Hugh

> ---
>  drivers/staging/ramster/zbud.c           |    2 +-
>  drivers/staging/zsmalloc/zsmalloc-main.c |    2 +-
>  include/linux/mm.h                       |   20 ++++++++++----------
>  mm/huge_memory.c                         |    2 +-
>  mm/mempolicy.c                           |    2 +-
>  mm/migrate.c                             |    4 ++--
>  mm/mmzone.c                              |    4 ++--
>  mm/page_alloc.c                          |   10 +++++-----
>  mm/slob.c                                |    2 +-
>  mm/slub.c                                |    2 +-
>  10 files changed, 25 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/staging/ramster/zbud.c b/drivers/staging/ramster/zbud.c
> index a7c4361..cc2deff 100644
> --- a/drivers/staging/ramster/zbud.c
> +++ b/drivers/staging/ramster/zbud.c
> @@ -401,7 +401,7 @@ static inline struct page *zbud_unuse_zbudpage(struct zbudpage *zbudpage,
>  	else
>  		zbud_pers_pageframes--;
>  	zbudpage_spin_unlock(zbudpage);
> -	reset_page_mapcount(page);
> +	page_mapcount_reset(page);
>  	init_page_count(page);
>  	page->index = 0;
>  	return page;
> diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c
> index 09a9d35..c7785f2 100644
> --- a/drivers/staging/zsmalloc/zsmalloc-main.c
> +++ b/drivers/staging/zsmalloc/zsmalloc-main.c
> @@ -475,7 +475,7 @@ static void reset_page(struct page *page)
>  	set_page_private(page, 0);
>  	page->mapping = NULL;
>  	page->freelist = NULL;
> -	reset_page_mapcount(page);
> +	page_mapcount_reset(page);
>  }
>  
>  static void free_zspage(struct page *first_page)
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 6e4468f..0aa0944 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -366,7 +366,7 @@ static inline struct page *compound_head(struct page *page)
>   * both from it and to it can be tracked, using atomic_inc_and_test
>   * and atomic_add_negative(-1).
>   */
> -static inline void reset_page_mapcount(struct page *page)
> +static inline void page_mapcount_reset(struct page *page)
>  {
>  	atomic_set(&(page)->_mapcount, -1);
>  }
> @@ -657,28 +657,28 @@ static inline int page_to_nid(const struct page *page)
>  
>  #ifdef CONFIG_NUMA_BALANCING
>  #ifdef LAST_NID_NOT_IN_PAGE_FLAGS
> -static inline int page_xchg_last_nid(struct page *page, int nid)
> +static inline int page_nid_xchg_last(struct page *page, int nid)
>  {
>  	return xchg(&page->_last_nid, nid);
>  }
>  
> -static inline int page_last_nid(struct page *page)
> +static inline int page_nid_last(struct page *page)
>  {
>  	return page->_last_nid;
>  }
> -static inline void reset_page_last_nid(struct page *page)
> +static inline void page_nid_reset_last(struct page *page)
>  {
>  	page->_last_nid = -1;
>  }
>  #else
> -static inline int page_last_nid(struct page *page)
> +static inline int page_nid_last(struct page *page)
>  {
>  	return (page->flags >> LAST_NID_PGSHIFT) & LAST_NID_MASK;
>  }
>  
> -extern int page_xchg_last_nid(struct page *page, int nid);
> +extern int page_nid_xchg_last(struct page *page, int nid);
>  
> -static inline void reset_page_last_nid(struct page *page)
> +static inline void page_nid_reset_last(struct page *page)
>  {
>  	int nid = (1 << LAST_NID_SHIFT) - 1;
>  
> @@ -687,17 +687,17 @@ static inline void reset_page_last_nid(struct page *page)
>  }
>  #endif /* LAST_NID_NOT_IN_PAGE_FLAGS */
>  #else
> -static inline int page_xchg_last_nid(struct page *page, int nid)
> +static inline int page_nid_xchg_last(struct page *page, int nid)
>  {
>  	return page_to_nid(page);
>  }
>  
> -static inline int page_last_nid(struct page *page)
> +static inline int page_nid_last(struct page *page)
>  {
>  	return page_to_nid(page);
>  }
>  
> -static inline void reset_page_last_nid(struct page *page)
> +static inline void page_nid_reset_last(struct page *page)
>  {
>  }
>  #endif
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 648c102..c52311a 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1642,7 +1642,7 @@ static void __split_huge_page_refcount(struct page *page)
>  		page_tail->mapping = page->mapping;
>  
>  		page_tail->index = page->index + i;
> -		page_xchg_last_nid(page_tail, page_last_nid(page));
> +		page_nid_xchg_last(page_tail, page_nid_last(page));
>  
>  		BUG_ON(!PageAnon(page_tail));
>  		BUG_ON(!PageUptodate(page_tail));
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index e2df1c1..db6fc14 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -2308,7 +2308,7 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
>  		 * it less likely we act on an unlikely task<->page
>  		 * relation.
>  		 */
> -		last_nid = page_xchg_last_nid(page, polnid);
> +		last_nid = page_nid_xchg_last(page, polnid);
>  		if (last_nid != polnid)
>  			goto out;
>  	}
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 8ef1cbf..88422a1 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1495,7 +1495,7 @@ static struct page *alloc_misplaced_dst_page(struct page *page,
>  					  __GFP_NOWARN) &
>  					 ~GFP_IOFS, 0);
>  	if (newpage)
> -		page_xchg_last_nid(newpage, page_last_nid(page));
> +		page_nid_xchg_last(newpage, page_nid_last(page));
>  
>  	return newpage;
>  }
> @@ -1679,7 +1679,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
>  	if (!new_page)
>  		goto out_fail;
>  
> -	page_xchg_last_nid(new_page, page_last_nid(page));
> +	page_nid_xchg_last(new_page, page_nid_last(page));
>  
>  	isolated = numamigrate_isolate_page(pgdat, page);
>  	if (!isolated) {
> diff --git a/mm/mmzone.c b/mm/mmzone.c
> index bce796e..2ac0afb 100644
> --- a/mm/mmzone.c
> +++ b/mm/mmzone.c
> @@ -98,14 +98,14 @@ void lruvec_init(struct lruvec *lruvec)
>  }
>  
>  #if defined(CONFIG_NUMA_BALANCING) && !defined(LAST_NID_NOT_IN_PAGE_FLAGS)
> -int page_xchg_last_nid(struct page *page, int nid)
> +int page_nid_xchg_last(struct page *page, int nid)
>  {
>  	unsigned long old_flags, flags;
>  	int last_nid;
>  
>  	do {
>  		old_flags = flags = page->flags;
> -		last_nid = page_last_nid(page);
> +		last_nid = page_nid_last(page);
>  
>  		flags &= ~(LAST_NID_MASK << LAST_NID_PGSHIFT);
>  		flags |= (nid & LAST_NID_MASK) << LAST_NID_PGSHIFT;
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index df2022f..2d525c8 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -287,7 +287,7 @@ static void bad_page(struct page *page)
>  
>  	/* Don't complain about poisoned pages */
>  	if (PageHWPoison(page)) {
> -		reset_page_mapcount(page); /* remove PageBuddy */
> +		page_mapcount_reset(page); /* remove PageBuddy */
>  		return;
>  	}
>  
> @@ -319,7 +319,7 @@ static void bad_page(struct page *page)
>  	dump_stack();
>  out:
>  	/* Leave bad fields for debug, except PageBuddy could make trouble */
> -	reset_page_mapcount(page); /* remove PageBuddy */
> +	page_mapcount_reset(page); /* remove PageBuddy */
>  	add_taint(TAINT_BAD_PAGE);
>  }
>  
> @@ -605,7 +605,7 @@ static inline int free_pages_check(struct page *page)
>  		bad_page(page);
>  		return 1;
>  	}
> -	reset_page_last_nid(page);
> +	page_nid_reset_last(page);
>  	if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
>  		page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
>  	return 0;
> @@ -3871,8 +3871,8 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
>  		set_page_links(page, zone, nid, pfn);
>  		mminit_verify_page_links(page, zone, nid, pfn);
>  		init_page_count(page);
> -		reset_page_mapcount(page);
> -		reset_page_last_nid(page);
> +		page_mapcount_reset(page);
> +		page_nid_reset_last(page);
>  		SetPageReserved(page);
>  		/*
>  		 * Mark the block movable so that blocks are reserved for
> diff --git a/mm/slob.c b/mm/slob.c
> index a99fdf7..eeed4a0 100644
> --- a/mm/slob.c
> +++ b/mm/slob.c
> @@ -360,7 +360,7 @@ static void slob_free(void *block, int size)
>  			clear_slob_page_free(sp);
>  		spin_unlock_irqrestore(&slob_lock, flags);
>  		__ClearPageSlab(sp);
> -		reset_page_mapcount(sp);
> +		page_mapcount_reset(sp);
>  		slob_free_pages(b, 0);
>  		return;
>  	}
> diff --git a/mm/slub.c b/mm/slub.c
> index ba2ca53..ebcc44e 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1408,7 +1408,7 @@ static void __free_slab(struct kmem_cache *s, struct page *page)
>  	__ClearPageSlab(page);
>  
>  	memcg_release_pages(s, order);
> -	reset_page_mapcount(page);
> +	page_mapcount_reset(page);
>  	if (current->reclaim_state)
>  		current->reclaim_state->reclaimed_slab += pages;
>  	__free_memcg_kmem_pages(page, order);
> 
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