linux-kernel - Re: [PATCH v2 2/4] mm: remove zone_lru_lock() function access ->lru

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Date:   Thu, 28 Feb 2019 22:56:35 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     John Hubbard <jhubbard@...dia.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Rik van Riel <riel@...riel.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Michal Hocko <mhocko@...nel.org>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: Re: [PATCH v2 2/4] mm: remove zone_lru_lock() function access
 ->lru_lock directly

On 2/28/2019 10:44 PM, John Hubbard wrote:
> Instead of removing that function, let's change it, and add another
> (since you have two cases: either a page* or a pgdat* is available),
> and move it to where it can compile, like this:
> 
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 80bb6408fe73..cea3437f5d68 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1167,6 +1167,16 @@ static inline pg_data_t *page_pgdat(const struct page *page)
>         return NODE_DATA(page_to_nid(page));
>  }
>  
> +static inline spinlock_t *zone_lru_lock(pg_data_t *pgdat)

In that case it should now be named node_lru_lock(). zone_lru_lock() was a
wrapper introduced to make the conversion of per-zone to per-node lru_lock smoother.

> +{
> +       return &pgdat->lru_lock;
> +}
> +
> +static inline spinlock_t *zone_lru_lock_from_page(struct page *page)

Ditto. Or maybe even page_node_lru_lock()?

> +{
> +       return zone_lru_lock(page_pgdat(page));
> +}
> +
>  #ifdef SECTION_IN_PAGE_FLAGS
>  static inline void set_page_section(struct page *page, unsigned long section)
>  {
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 842f9189537b..e03042fe1d88 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -728,11 +728,6 @@ typedef struct pglist_data {
>  
>  #define node_start_pfn(nid)    (NODE_DATA(nid)->node_start_pfn)
>  #define node_end_pfn(nid) pgdat_end_pfn(NODE_DATA(nid))
> -static inline spinlock_t *zone_lru_lock(struct zone *zone)
> -{
> -       return &zone->zone_pgdat->lru_lock;
> -}
> -
>  static inline struct lruvec *node_lruvec(struct pglist_data *pgdat)
>  {
>         return &pgdat->lruvec;
> 
> 
> 
> Like it?
> 
> thanks,
>