mm: vmscan: do not writeback filesystem pages in kswapd except in high priority

[pandora-kernel.git] / mm / vmscan.c

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5c59665..15e3a29 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -750,7 +750,8 @@ static noinline_for_stack void free_page_list(struct list_head *free_pages)
  */
 static unsigned long shrink_page_list(struct list_head *page_list,
                                      struct zone *zone,
-                                     struct scan_control *sc)
+                                     struct scan_control *sc,
+                                     int priority)
 {
        LIST_HEAD(ret_pages);
        LIST_HEAD(free_pages);
@@ -856,9 +857,11 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 
                        /*
                         * Only kswapd can writeback filesystem pages to
-                        * avoid risk of stack overflow
+                        * avoid risk of stack overflow but do not writeback
+                        * unless under significant pressure.
                         */
-                       if (page_is_file_cache(page) && !current_is_kswapd()) {
+                       if (page_is_file_cache(page) &&
+                                       (!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) {
                                inc_zone_page_state(page, NR_VMSCAN_WRITE_SKIP);
                                goto keep_locked;
                        }
@@ -1509,12 +1512,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
 
        spin_unlock_irq(&zone->lru_lock);
 
-       nr_reclaimed = shrink_page_list(&page_list, zone, sc);
+       nr_reclaimed = shrink_page_list(&page_list, zone, sc, priority);
 
        /* Check if we should syncronously wait for writeback */
        if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
                set_reclaim_mode(priority, sc, true);
-               nr_reclaimed += shrink_page_list(&page_list, zone, sc);
+               nr_reclaimed += shrink_page_list(&page_list, zone, sc, priority);
        }
 
        local_irq_disable();