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Commit b35ea17b authored by KOSAKI Motohiro's avatar KOSAKI Motohiro Committed by Linus Torvalds
Browse files

mm: shrink_inactive_list() nr_scan accounting fix fix 



If sc->isolate_pages() return 0, we don't need to call shrink_page_list().
In past days, shrink_inactive_list() handled it properly.

But commit fb8d14e1 (three years ago commit!) breaked it.  current
shrink_inactive_list() always call shrink_page_list() although
isolate_pages() return 0.

This patch restore proper return value check.

Requirements:
  o "nr_taken == 0" condition should stay before calling shrink_page_list().
  o "nr_taken == 0" condition should stay after nr_scan related statistics
     modification.

Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 44c241f1

mm/vmscan.c

+18 −12
Original line number Diff line number Diff line
@@ -1076,6 +1076,20 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, 
		nr_taken = sc->isolate_pages(sc->swap_cluster_max,

			     &page_list, &nr_scan, sc->order, mode,

				zone, sc->mem_cgroup, 0, file);



		if (scanning_global_lru(sc)) {

			zone->pages_scanned += nr_scan;

			if (current_is_kswapd())

				__count_zone_vm_events(PGSCAN_KSWAPD, zone,

						       nr_scan);

			else

				__count_zone_vm_events(PGSCAN_DIRECT, zone,

						       nr_scan);

		}



		if (nr_taken == 0)

			goto done;



		nr_active = clear_active_flags(&page_list, count);

		__count_vm_events(PGDEACTIVATE, nr_active);
@@ -1088,8 +1102,6 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, 
		__mod_zone_page_state(zone, NR_INACTIVE_ANON,

						-count[LRU_INACTIVE_ANON]);



		if (scanning_global_lru(sc))

			zone->pages_scanned += nr_scan;



		reclaim_stat->recent_scanned[0] += count[LRU_INACTIVE_ANON];

		reclaim_stat->recent_scanned[0] += count[LRU_ACTIVE_ANON];
@@ -1123,18 +1135,12 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, 
		}



		nr_reclaimed += nr_freed;



		local_irq_disable();

		if (current_is_kswapd()) {

			__count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scan);

		if (current_is_kswapd())

			__count_vm_events(KSWAPD_STEAL, nr_freed);

		} else if (scanning_global_lru(sc))

			__count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scan);



		__count_zone_vm_events(PGSTEAL, zone, nr_freed);



		if (nr_taken == 0)

			goto done;



		spin_lock(&zone->lru_lock);

		/*

		 * Put back any unfreeable pages.
@@ -1164,9 +1170,9 @@ static unsigned long shrink_inactive_list(unsigned long max_scan, 
			}

		}

  	} while (nr_scanned < max_scan);

	spin_unlock(&zone->lru_lock);



done:

	local_irq_enable();

	spin_unlock_irq(&zone->lru_lock);

	pagevec_release(&pvec);

	return nr_reclaimed;

}