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-rw-r--r--mm/vmscan.c31
1 files changed, 25 insertions, 6 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1505c573719d..d6c916d808ba 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -676,13 +676,14 @@ static unsigned long shrink_page_list(struct list_head *page_list,
struct zone *zone,
struct scan_control *sc,
enum ttu_flags ttu_flags,
- unsigned long *ret_nr_dirty,
+ unsigned long *ret_nr_unqueued_dirty,
unsigned long *ret_nr_writeback,
bool force_reclaim)
{
LIST_HEAD(ret_pages);
LIST_HEAD(free_pages);
int pgactivate = 0;
+ unsigned long nr_unqueued_dirty = 0;
unsigned long nr_dirty = 0;
unsigned long nr_congested = 0;
unsigned long nr_reclaimed = 0;
@@ -808,14 +809,17 @@ static unsigned long shrink_page_list(struct list_head *page_list,
if (PageDirty(page)) {
nr_dirty++;
+ if (!PageWriteback(page))
+ nr_unqueued_dirty++;
+
/*
* Only kswapd can writeback filesystem pages to
- * avoid risk of stack overflow but do not writeback
- * unless under significant pressure.
+ * avoid risk of stack overflow but only writeback
+ * if many dirty pages have been encountered.
*/
if (page_is_file_cache(page) &&
(!current_is_kswapd() ||
- sc->priority >= DEF_PRIORITY - 2)) {
+ !zone_is_reclaim_dirty(zone))) {
/*
* Immediately reclaim when written back.
* Similar in principal to deactivate_page()
@@ -960,7 +964,7 @@ keep:
list_splice(&ret_pages, page_list);
count_vm_events(PGACTIVATE, pgactivate);
mem_cgroup_uncharge_end();
- *ret_nr_dirty += nr_dirty;
+ *ret_nr_unqueued_dirty += nr_unqueued_dirty;
*ret_nr_writeback += nr_writeback;
return nr_reclaimed;
}
@@ -1373,6 +1377,15 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
(nr_taken >> (DEF_PRIORITY - sc->priority)))
wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);
+ /*
+ * Similarly, if many dirty pages are encountered that are not
+ * currently being written then flag that kswapd should start
+ * writing back pages.
+ */
+ if (global_reclaim(sc) && nr_dirty &&
+ nr_dirty >= (nr_taken >> (DEF_PRIORITY - sc->priority)))
+ zone_set_flag(zone, ZONE_TAIL_LRU_DIRTY);
+
trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
zone_idx(zone),
nr_scanned, nr_reclaimed,
@@ -2769,8 +2782,12 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
end_zone = i;
break;
} else {
- /* If balanced, clear the congested flag */
+ /*
+ * If balanced, clear the dirty and congested
+ * flags
+ */
zone_clear_flag(zone, ZONE_CONGESTED);
+ zone_clear_flag(zone, ZONE_TAIL_LRU_DIRTY);
}
}
@@ -2888,8 +2905,10 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order,
* possible there are dirty pages backed by
* congested BDIs but as pressure is relieved,
* speculatively avoid congestion waits
+ * or writing pages from kswapd context.
*/
zone_clear_flag(zone, ZONE_CONGESTED);
+ zone_clear_flag(zone, ZONE_TAIL_LRU_DIRTY);
}
/*