Commit 5d7d362abc408e69ee229459fba21f833f2f5bf1

Authored by Ming Ling
Committed by Greg Kroah-Hartman
1 parent dc1b6d0aed

mm, compaction: fix NR_ISOLATED_* stats for pfn based migration

commit 6afcf8ef0ca0a69d014f8edb613d94821f0ae700 upstream.

Since commit bda807d44454 ("mm: migrate: support non-lru movable page
migration") isolate_migratepages_block) can isolate !PageLRU pages which
would acct_isolated account as NR_ISOLATED_*.  Accounting these non-lru
pages NR_ISOLATED_{ANON,FILE} doesn't make any sense and it can misguide
heuristics based on those counters such as pgdat_reclaimable_pages resp.
too_many_isolated which would lead to unexpected stalls during the
direct reclaim without any good reason.  Note that
__alloc_contig_migrate_range can isolate a lot of pages at once.

On mobile devices such as 512M ram android Phone, it may use a big zram
swap.  In some cases zram(zsmalloc) uses too many non-lru but
migratedable pages, such as:

      MemTotal: 468148 kB
      Normal free:5620kB
      Free swap:4736kB
      Total swap:409596kB
      ZRAM: 164616kB(zsmalloc non-lru pages)
      active_anon:60700kB
      inactive_anon:60744kB
      active_file:34420kB
      inactive_file:37532kB

Fix this by only accounting lru pages to NR_ISOLATED_* in
isolate_migratepages_block right after they were isolated and we still
know they were on LRU.  Drop acct_isolated because it is called after
the fact and we've lost that information.  Batching per-cpu counter
doesn't make much improvement anyway.  Also make sure that we uncharge
only LRU pages when putting them back on the LRU in
putback_movable_pages resp.  when unmap_and_move migrates the page.

[mhocko@suse.com: replace acct_isolated() with direct counting]
Fixes: bda807d44454 ("mm: migrate: support non-lru movable page migration")
Link: http://lkml.kernel.org/r/20161019080240.9682-1-mhocko@kernel.org
Signed-off-by: Ming Ling <ming.ling@spreadtrum.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 2 changed files with 14 additions and 26 deletions Side-by-side Diff

... ... @@ -634,22 +634,6 @@
634 634 return pfn;
635 635 }
636 636  
637   -/* Update the number of anon and file isolated pages in the zone */
638   -static void acct_isolated(struct zone *zone, struct compact_control *cc)
639   -{
640   - struct page *page;
641   - unsigned int count[2] = { 0, };
642   -
643   - if (list_empty(&cc->migratepages))
644   - return;
645   -
646   - list_for_each_entry(page, &cc->migratepages, lru)
647   - count[!!page_is_file_cache(page)]++;
648   -
649   - mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_ANON, count[0]);
650   - mod_node_page_state(zone->zone_pgdat, NR_ISOLATED_FILE, count[1]);
651   -}
652   -
653 637 /* Similar to reclaim, but different enough that they don't share logic */
654 638 static bool too_many_isolated(struct zone *zone)
655 639 {
... ... @@ -866,6 +850,8 @@
866 850  
867 851 /* Successfully isolated */
868 852 del_page_from_lru_list(page, lruvec, page_lru(page));
  853 + inc_node_page_state(page,
  854 + NR_ISOLATED_ANON + page_is_file_cache(page));
869 855  
870 856 isolate_success:
871 857 list_add(&page->lru, &cc->migratepages);
... ... @@ -902,7 +888,6 @@
902 888 spin_unlock_irqrestore(zone_lru_lock(zone), flags);
903 889 locked = false;
904 890 }
905   - acct_isolated(zone, cc);
906 891 putback_movable_pages(&cc->migratepages);
907 892 cc->nr_migratepages = 0;
908 893 cc->last_migrated_pfn = 0;
... ... @@ -988,7 +973,6 @@
988 973 if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
989 974 break;
990 975 }
991   - acct_isolated(cc->zone, cc);
992 976  
993 977 return pfn;
994 978 }
995 979  
... ... @@ -1258,10 +1242,8 @@
1258 1242 low_pfn = isolate_migratepages_block(cc, low_pfn,
1259 1243 block_end_pfn, isolate_mode);
1260 1244  
1261   - if (!low_pfn || cc->contended) {
1262   - acct_isolated(zone, cc);
  1245 + if (!low_pfn || cc->contended)
1263 1246 return ISOLATE_ABORT;
1264   - }
1265 1247  
1266 1248 /*
1267 1249 * Either we isolated something and proceed with migration. Or
... ... @@ -1271,7 +1253,6 @@
1271 1253 break;
1272 1254 }
1273 1255  
1274   - acct_isolated(zone, cc);
1275 1256 /* Record where migration scanner will be restarted. */
1276 1257 cc->migrate_pfn = low_pfn;
1277 1258  
... ... @@ -168,8 +168,6 @@
168 168 continue;
169 169 }
170 170 list_del(&page->lru);
171   - dec_node_page_state(page, NR_ISOLATED_ANON +
172   - page_is_file_cache(page));
173 171 /*
174 172 * We isolated non-lru movable page so here we can use
175 173 * __PageMovable because LRU page's mapping cannot have
... ... @@ -186,6 +184,8 @@
186 184 put_page(page);
187 185 } else {
188 186 putback_lru_page(page);
  187 + dec_node_page_state(page, NR_ISOLATED_ANON +
  188 + page_is_file_cache(page));
189 189 }
190 190 }
191 191 }
... ... @@ -1121,8 +1121,15 @@
1121 1121 * restored.
1122 1122 */
1123 1123 list_del(&page->lru);
1124   - dec_node_page_state(page, NR_ISOLATED_ANON +
1125   - page_is_file_cache(page));
  1124 +
  1125 + /*
  1126 + * Compaction can migrate also non-LRU pages which are
  1127 + * not accounted to NR_ISOLATED_*. They can be recognized
  1128 + * as __PageMovable
  1129 + */
  1130 + if (likely(!__PageMovable(page)))
  1131 + dec_node_page_state(page, NR_ISOLATED_ANON +
  1132 + page_is_file_cache(page));
1126 1133 }
1127 1134  
1128 1135 /*