Re: [PATCH RFC 1/4] mm/page_alloc: convert "report" flag of __free_one_page() to a proper flag

[Alexander Duyck]

On Wed, Sep 16, 2020 at 11:34 AM David Hildenbrand <david@xxxxxxxxxx> wrote:
>
> Let's prepare for additional flags and avoid long parameter lists of bools.
> Follow-up patches will also make use of the flags in __free_pages_ok(),
> however, I wasn't able to come up with a better name for the type - should
> be good enough for internal purposes.
>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx>
> Cc: Oscar Salvador <osalvador@xxxxxxx>
> Cc: Mike Rapoport <rppt@xxxxxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
> ---
>  mm/page_alloc.c | 28 ++++++++++++++++++++--------
>  1 file changed, 20 insertions(+), 8 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 6b699d273d6e..91cefb8157dd 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -77,6 +77,18 @@
>  #include "shuffle.h"
>  #include "page_reporting.h"
>
> +/* Free One Page flags: for internal, non-pcp variants of free_pages(). */
> +typedef int __bitwise fop_t;
> +
> +/* No special request */
> +#define FOP_NONE               ((__force fop_t)0)
> +
> +/*
> + * Skip free page reporting notification after buddy merging (will *not* mark
> + * the page reported, only skip the notification).
> + */
> +#define FOP_SKIP_REPORT_NOTIFY ((__force fop_t)BIT(0))
> +
>  /* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
>  static DEFINE_MUTEX(pcp_batch_high_lock);
>  #define MIN_PERCPU_PAGELIST_FRACTION   (8)
> @@ -948,10 +960,9 @@ buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn,
>   * -- nyc
>   */
>
> -static inline void __free_one_page(struct page *page,
> -               unsigned long pfn,
> -               struct zone *zone, unsigned int order,
> -               int migratetype, bool report)
> +static inline void __free_one_page(struct page *page, unsigned long pfn,
> +                                  struct zone *zone, unsigned int order,
> +                                  int migratetype, fop_t fop_flags)
>  {
>         struct capture_control *capc = task_capc(zone);
>         unsigned long buddy_pfn;
> @@ -1038,7 +1049,7 @@ static inline void __free_one_page(struct page *page,
>                 add_to_free_list(page, zone, order, migratetype);
>
>         /* Notify page reporting subsystem of freed page */
> -       if (report)
> +       if (!(fop_flags & FOP_SKIP_REPORT_NOTIFY))
>                 page_reporting_notify_free(order);
>  }
>
> @@ -1368,7 +1379,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
>                 if (unlikely(isolated_pageblocks))
>                         mt = get_pageblock_migratetype(page);
>
> -               __free_one_page(page, page_to_pfn(page), zone, 0, mt, true);
> +               __free_one_page(page, page_to_pfn(page), zone, 0, mt, FOP_NONE);
>                 trace_mm_page_pcpu_drain(page, 0, mt);
>         }
>         spin_unlock(&zone->lock);
> @@ -1384,7 +1395,7 @@ static void free_one_page(struct zone *zone,
>                 is_migrate_isolate(migratetype))) {
>                 migratetype = get_pfnblock_migratetype(page, pfn);
>         }
> -       __free_one_page(page, pfn, zone, order, migratetype, true);
> +       __free_one_page(page, pfn, zone, order, migratetype, FOP_NONE);
>         spin_unlock(&zone->lock);
>  }
>
> @@ -3277,7 +3288,8 @@ void __putback_isolated_page(struct page *page, unsigned int order, int mt)
>         lockdep_assert_held(&zone->lock);
>
>         /* Return isolated page to tail of freelist. */
> -       __free_one_page(page, page_to_pfn(page), zone, order, mt, false);
> +       __free_one_page(page, page_to_pfn(page), zone, order, mt,
> +                       FOP_SKIP_REPORT_NOTIFY);
>  }
>
>  /*

Seems pretty straight forward. So we are basically flipping the logic
and replacing !report with FOP_SKIP_REPORT_NOTIFY.

Reviewed-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>