From: Hugh Dickins <[email protected]> /proc/sys/vm/stat_refresh warns nr_isolated_anon and nr_isolated_file go increasingly negative under compaction: which would add delay when should be none, or no delay when should delay. putback_movable_pages() decrements the NR_ISOLATED counts which acct_isolated() increments, so isolate_migratepages_block() needs to acct before putback in that special case. It's also useful to reset cc->nr_migratepages after putback so we don't needlessly return too early on the COMPACT_CLUSTER_MAX check.
Also it's easier to track the life of cc->migratepages if we don't assign it to a migratelist variable. Fixes: mmotm mm-compaction-skip-blocks-where-isolation-fails-in-async-direct-compaction.patch Signed-off-by: Hugh Dickins <[email protected]> Signed-off-by: Vlastimil Babka <[email protected]> --- mm/compaction.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 6a49d1b35515..78552009e6ec 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -638,7 +638,6 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, { struct zone *zone = cc->zone; unsigned long nr_scanned = 0, nr_isolated = 0; - struct list_head *migratelist = &cc->migratepages; struct lruvec *lruvec; unsigned long flags = 0; bool locked = false; @@ -812,7 +811,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, del_page_from_lru_list(page, lruvec, page_lru(page)); isolate_success: - list_add(&page->lru, migratelist); + list_add(&page->lru, &cc->migratepages); cc->nr_migratepages++; nr_isolated++; @@ -846,9 +845,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, spin_unlock_irqrestore(&zone->lru_lock, flags); locked = false; } - putback_movable_pages(migratelist); - nr_isolated = 0; + acct_isolated(zone, cc); + putback_movable_pages(&cc->migratepages); + cc->nr_migratepages = 0; cc->last_migrated_pfn = 0; + nr_isolated = 0; } if (low_pfn < next_skip_pfn) { -- 2.8.1
