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Commit cb8d68ec authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
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thp: change deferred_split_count() to return number of THP in queue 



I've got meaning of shrinker::count_objects() wrong: it should return
number of potentially freeable objects, which is not necessary correlate
with freeable memory.

Returning 256 per THP in queue is not reasonable:
shrinker::scan_objects() never called with nr_to_scan > 128 in my setup.

Let's return 1 per THP and correct scan_object accordingly.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a3d0a918

mm/huge_memory.c

+8 −7
Original line number Diff line number Diff line
@@ -3465,12 +3465,7 @@ static unsigned long deferred_split_count(struct shrinker *shrink, 
		struct shrink_control *sc)

{

	struct pglist_data *pgdata = NODE_DATA(sc->nid);

	/*

	 * Split a page from split_queue will free up at least one page,

	 * at most HPAGE_PMD_NR - 1. We don't track exact number.

	 * Let's use HPAGE_PMD_NR / 2 as ballpark.

	 */

	return ACCESS_ONCE(pgdata->split_queue_len) * HPAGE_PMD_NR / 2;

	return ACCESS_ONCE(pgdata->split_queue_len);

}



static unsigned long deferred_split_scan(struct shrinker *shrink,
@@ -3511,7 +3506,13 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, 
	list_splice_tail(&list, &pgdata->split_queue);

	spin_unlock_irqrestore(&pgdata->split_queue_lock, flags);



	return split * HPAGE_PMD_NR / 2;

	/*

	 * Stop shrinker if we didn't split any page, but the queue is empty.

	 * This can happen if pages were freed under us.

	 */

	if (!split && list_empty(&pgdata->split_queue))

		return SHRINK_STOP;

	return split;

}



static struct shrinker deferred_split_shrinker = {