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Date:   Wed, 21 Jul 2021 12:51:57 +0300
From:   Mike Rapoport <rppt@kernel.org>
To:     "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        linux-fsdevel@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v14 050/138] mm/workingset: Convert workingset_activation
 to take a folio
Message-ID: <YPfuPTtlhGXBjhCL@kernel.org>
References: <20210715033704.692967-1-willy@infradead.org>
 <20210715033704.692967-51-willy@infradead.org>
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On Thu, Jul 15, 2021 at 04:35:36AM +0100, Matthew Wilcox (Oracle) wrote:
> This function already assumed it was being passed a head page.  No real
> change here, except that thp_nr_pages() compiles away on kernels with
> THP compiled out while folio_nr_pages() is always present.  Also convert
> page_memcg_rcu() to folio_memcg_rcu().
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>  include/linux/memcontrol.h | 18 +++++++++---------
>  include/linux/swap.h       |  2 +-
>  mm/swap.c                  |  2 +-
>  mm/workingset.c            | 11 ++++-------
>  4 files changed, 15 insertions(+), 18 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 6511f89ad454..2dd660185bb3 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -461,19 +461,19 @@ static inline struct mem_cgroup *page_memcg(struct page *page)
>  }
>  
>  /*
> - * page_memcg_rcu - locklessly get the memory cgroup associated with a page
> - * @page: a pointer to the page struct
> + * folio_memcg_rcu - Locklessly get the memory cgroup associated with a folio.
> + * @folio: Pointer to the folio.
>   *
> - * Returns a pointer to the memory cgroup associated with the page,
> - * or NULL. This function assumes that the page is known to have a
> + * Returns a pointer to the memory cgroup associated with the folio,
> + * or NULL. This function assumes that the folio is known to have a
>   * proper memory cgroup pointer. It's not safe to call this function
> - * against some type of pages, e.g. slab pages or ex-slab pages.
> + * against some type of folios, e.g. slab folios or ex-slab folios.

Maybe

- * Returns a pointer to the memory cgroup associated with the page,
- * or NULL. This function assumes that the page is known to have a
+ * This function assumes that the folio is known to have a
  * proper memory cgroup pointer. It's not safe to call this function
- * against some type of pages, e.g. slab pages or ex-slab pages.
+ * against some type of folios, e.g. slab folios or ex-slab folios.
+ *
+ * Return: a pointer to the memory cgroup associated with the folio,
+ * or NULL.

>   */
> -static inline struct mem_cgroup *page_memcg_rcu(struct page *page)
> +static inline struct mem_cgroup *folio_memcg_rcu(struct folio *folio)
>  {
> -	unsigned long memcg_data = READ_ONCE(page->memcg_data);
> +	unsigned long memcg_data = READ_ONCE(folio->memcg_data);
>  
> -	VM_BUG_ON_PAGE(PageSlab(page), page);
> +	VM_BUG_ON_FOLIO(folio_test_slab(folio), folio);
>  	WARN_ON_ONCE(!rcu_read_lock_held());
>  
>  	if (memcg_data & MEMCG_DATA_KMEM) {
> @@ -1129,7 +1129,7 @@ static inline struct mem_cgroup *page_memcg(struct page *page)
>  	return NULL;
>  }
>  
> -static inline struct mem_cgroup *page_memcg_rcu(struct page *page)
> +static inline struct mem_cgroup *folio_memcg_rcu(struct folio *folio)
>  {
>  	WARN_ON_ONCE(!rcu_read_lock_held());
>  	return NULL;
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 8394716a002b..989d8f78c256 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -330,7 +330,7 @@ static inline swp_entry_t folio_swap_entry(struct folio *folio)
>  void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages);
>  void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg);
>  void workingset_refault(struct page *page, void *shadow);
> -void workingset_activation(struct page *page);
> +void workingset_activation(struct folio *folio);
>  
>  /* Only track the nodes of mappings with shadow entries */
>  void workingset_update_node(struct xa_node *node);
> diff --git a/mm/swap.c b/mm/swap.c
> index aa9c32b714c5..85969b36b636 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -451,7 +451,7 @@ void mark_page_accessed(struct page *page)
>  		else
>  			__lru_cache_activate_page(page);
>  		ClearPageReferenced(page);
> -		workingset_activation(page);
> +		workingset_activation(page_folio(page));
>  	}
>  	if (page_is_idle(page))
>  		clear_page_idle(page);
> diff --git a/mm/workingset.c b/mm/workingset.c
> index e62c0f2084a2..39bb60d50217 100644
> --- a/mm/workingset.c
> +++ b/mm/workingset.c
> @@ -392,13 +392,11 @@ void workingset_refault(struct page *page, void *shadow)
>  
>  /**
>   * workingset_activation - note a page activation
> - * @page: page that is being activated
> + * @folio: Folio that is being activated.
>   */
> -void workingset_activation(struct page *page)
> +void workingset_activation(struct folio *folio)
>  {
> -	struct folio *folio = page_folio(page);
>  	struct mem_cgroup *memcg;
> -	struct lruvec *lruvec;
>  
>  	rcu_read_lock();
>  	/*
> @@ -408,11 +406,10 @@ void workingset_activation(struct page *page)
>  	 * XXX: See workingset_refault() - this should return
>  	 * root_mem_cgroup even for !CONFIG_MEMCG.
>  	 */
> -	memcg = page_memcg_rcu(page);
> +	memcg = folio_memcg_rcu(folio);
>  	if (!mem_cgroup_disabled() && !memcg)
>  		goto out;
> -	lruvec = folio_lruvec(folio);
> -	workingset_age_nonresident(lruvec, thp_nr_pages(page));
> +	workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio));
>  out:
>  	rcu_read_unlock();
>  }
> -- 
> 2.30.2
> 
> 

-- 
Sincerely yours,
Mike.