From: Hugh Dickins <hughd@xxxxxxxxxx> Subject: mm, compaction: don't isolate PageWriteback pages in MIGRATE_SYNC_LIGHT mode At present MIGRATE_SYNC_LIGHT is allowing __isolate_lru_page() to isolate a PageWriteback page, which __unmap_and_move() then rejects with -EBUSY: of course the writeback might complete in between, but that's not what we usually expect, so probably better not to isolate it. When tested by stress-highalloc from mmtests, this has reduced the number of page migrate failures by 60-70%. Link: http://lkml.kernel.org/r/20160721073614.24395-2-vbabka@xxxxxxx Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN mm/compaction.c~mm-compaction-dont-isolate-pagewriteback-pages-in-migrate_sync_light-mode mm/compaction.c --- a/mm/compaction.c~mm-compaction-dont-isolate-pagewriteback-pages-in-migrate_sync_light-mode +++ a/mm/compaction.c @@ -1200,7 +1200,7 @@ static isolate_migrate_t isolate_migrate struct page *page; const isolate_mode_t isolate_mode = (sysctl_compact_unevictable_allowed ? ISOLATE_UNEVICTABLE : 0) | - (cc->mode == MIGRATE_ASYNC ? ISOLATE_ASYNC_MIGRATE : 0); + (cc->mode != MIGRATE_SYNC ? ISOLATE_ASYNC_MIGRATE : 0); /* * Start at where we last stopped, or beginning of the zone as _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
