Re: [PATCH v1 1/5] mm/page_alloc: convert "report" flag of __free_one_page() to a proper flag

Michal Hocko
2020-10-02T13:17:48Z

On Mon 28-09-20 20:21:06, David Hildenbrand 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.
>
> Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
> Reviewed-by: Oscar Salvador <osalvador@suse.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Dave Hansen <dave.hansen@intel.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Mike Rapoport <rppt@kernel.org>
> Signed-off-by: David Hildenbrand <david@redhat.com>

Hopefully this will not wrack the generated code. But considering we
would need another parameter there is not much choice left.

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
> 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 df90e3654f97..daab90e960fe 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 for the (possibly merged) page. (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);
> }
>
> @@ -1379,7 +1390,7 @@ 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);
> @@ -1395,7 +1406,7 @@ 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);
> }
>
> @@ -3288,7 +3299,8 @@ 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);
> }
>
> /*
> --
> 2.26.2

--
Michal Hocko
SUSE Labs