On 08/17/2016 06:48 AM, Ralf-Peter Rohbeck wrote: >> ------------>8----------- >> diff --git a/mm/compaction.c b/mm/compaction.c >> index 9affb29..965eddd 100644 >> --- a/mm/compaction.c >> +++ b/mm/compaction.c >> @@ -1082,10 +1082,6 @@ static void isolate_freepages(struct compact_control *cc) >> if (!page) >> continue; >> >> - /* Check the block is suitable for migration */ >> - if (!suitable_migration_target(page)) >> - continue; >> - >> /* If isolation recently failed, do not retry */ >> if (!isolation_suitable(cc, page)) >> continue; >> > That seemed to help a little (subjectively) but still OOM killed a > kernel build. The logs are attached. > grep XXX messages Aug 16 20:29:13 fs kernel: [ 6850.467250] XXX: compaction_failed pagetypeinfo_after: Number of blocks type Unmovable Movable Reclaimable HighAtomic Isolate Node 0, zone DMA 1 7 0 0 0 Node 0, zone DMA32 879 93 44 0 0 Node 0, zone Normal 2862 136 74 0 0 vmstat_after: pgmigrate_success 5123 pgmigrate_fail 4106 compact_migrate_scanned 62019 compact_free_scanned 44314328 compact_isolated 18572 compact_stall 327 compact_fail 236 compact_success 91 compact_daemon_wake 1162 > grep try_to_release trace_pipe.log | wc -l 0 Again, migration failures are there but not so many, and failures to isolate freepages stand out. I assume it's because the kernel build workload and not the btrfs balance one. I think the patches in mmotm could make compaction try harder and use more appropriate watermarks, but it's not guaranteed that will help. The free scanner seems to become more and more a fundamental problem. And I really wonder how did all those unmovable pageblocks happen. AFAICS zoneinfo shows that most of memory is occupied by file lru pages. These should be movable. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>