Missing Bartlomiej, Sorry!
On 06/14/2012 10:12 AM, Minchan Kim wrote:
> __count_immobile_pages naming is rather awkward.
> This patch changes function name more clear and add comment.
>
> * changelog from v1
> - write down page flag race in function comment
> - commit change log change
>
> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxx>
> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> ---
> mm/page_alloc.c | 34 ++++++++++++++++++----------------
> 1 file changed, 18 insertions(+), 16 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 543cc2d..dc7f8c5 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5467,26 +5467,28 @@ void set_pageblock_flags_group(struct page *page, unsigned long flags,
> }
>
> /*
> - * This is designed as sub function...plz see page_isolation.c also.
> - * set/clear page block's type to be ISOLATE.
> - * page allocater never alloc memory from ISOLATE block.
> + * This function checks whether pageblock includes unmovable pages or not.
> + * If @count is not zero, it is okay to include less @count unmovable pages
> + *
> + * PageLRU check wihtout isolation or lru_lock could race so that
> + * MIGRATE_MOVABLE block might include unmovable pages. It means you can't
> + * expect this function should be exact.
> */
> -
> -static int
> -__count_immobile_pages(struct zone *zone, struct page *page, int count)
> +static bool
> +__has_unmovable_pages(struct zone *zone, struct page *page, int count)
> {
> unsigned long pfn, iter, found;
> int mt;
>
> /*
> * For avoiding noise data, lru_add_drain_all() should be called
> - * If ZONE_MOVABLE, the zone never contains immobile pages
> + * If ZONE_MOVABLE, the zone never contains unmovable pages
> */
> if (zone_idx(zone) == ZONE_MOVABLE)
> - return true;
> + return false;
> mt = get_pageblock_migratetype(page);
> if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt))
> - return true;
> + return false;
>
> pfn = page_to_pfn(page);
> for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) {
> @@ -5524,9 +5526,9 @@ __count_immobile_pages(struct zone *zone, struct page *page, int count)
> * page at boot.
> */
> if (found > count)
> - return false;
> + return true;
> }
> - return true;
> + return false;
> }
>
> bool is_pageblock_removable_nolock(struct page *page)
> @@ -5550,7 +5552,7 @@ bool is_pageblock_removable_nolock(struct page *page)
> zone->zone_start_pfn + zone->spanned_pages <= pfn)
> return false;
>
> - return __count_immobile_pages(zone, page, 0);
> + return !__has_unmovable_pages(zone, page, 0);
> }
>
> int set_migratetype_isolate(struct page *page)
> @@ -5589,12 +5591,12 @@ int set_migratetype_isolate(struct page *page)
> * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
> * We just check MOVABLE pages.
> */
> - if (__count_immobile_pages(zone, page, arg.pages_found))
> + if (!__has_unmovable_pages(zone, page, arg.pages_found))
> ret = 0;
> -
> /*
> - * immobile means "not-on-lru" paes. If immobile is larger than
> - * removable-by-driver pages reported by notifier, we'll fail.
> + * Unmovable means "not-on-lru" pages. If Unmovable pages are
> + * larger than removable-by-driver pages reported by notifier,
> + * we'll fail.
> */
>
> out:
--
Kind regards,
Minchan Kim
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