Merge branches 'perf-fixes-for-linus' and 'x86-fixes-for-linus' of git://git.kernel...

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

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 130ad02..b8a6fdc 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -401,10 +401,8 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
        }
        if (mapping->a_ops->writepage == NULL)
                return PAGE_ACTIVATE;
-       if (!may_write_to_queue(mapping->backing_dev_info, sc)) {
-               disable_lumpy_reclaim_mode(sc);
+       if (!may_write_to_queue(mapping->backing_dev_info, sc))
                return PAGE_KEEP;
-       }
 
        if (clear_page_dirty_for_io(page)) {
                int res;
@@ -653,7 +651,7 @@ static enum page_references page_check_references(struct page *page,
        }
 
        /* Reclaim if clean, defer dirty pages to writeback */
-       if (referenced_page)
+       if (referenced_page && !PageSwapBacked(page))
                return PAGEREF_RECLAIM_CLEAN;
 
        return PAGEREF_RECLAIM;
@@ -681,11 +679,14 @@ static noinline_for_stack void free_page_list(struct list_head *free_pages)
  * shrink_page_list() returns the number of reclaimed pages
  */
 static unsigned long shrink_page_list(struct list_head *page_list,
+                                     struct zone *zone,
                                      struct scan_control *sc)
 {
        LIST_HEAD(ret_pages);
        LIST_HEAD(free_pages);
        int pgactivate = 0;
+       unsigned long nr_dirty = 0;
+       unsigned long nr_congested = 0;
        unsigned long nr_reclaimed = 0;
 
        cond_resched();
@@ -705,6 +706,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                        goto keep;
 
                VM_BUG_ON(PageActive(page));
+               VM_BUG_ON(page_zone(page) != zone);
 
                sc->nr_scanned++;
 
@@ -782,6 +784,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                }
 
                if (PageDirty(page)) {
+                       nr_dirty++;
+
                        if (references == PAGEREF_RECLAIM_CLEAN)
                                goto keep_locked;
                        if (!may_enter_fs)
@@ -792,6 +796,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                        /* Page is dirty, try to write it out here */
                        switch (pageout(page, mapping, sc)) {
                        case PAGE_KEEP:
+                               nr_congested++;
                                goto keep_locked;
                        case PAGE_ACTIVATE:
                                goto activate_locked;
@@ -902,6 +907,15 @@ keep_lumpy:
                VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
        }
 
+       /*
+        * Tag a zone as congested if all the dirty pages encountered were
+        * backed by a congested BDI. In this case, reclaimers should just
+        * back off and wait for congestion to clear because further reclaim
+        * will encounter the same problem
+        */
+       if (nr_dirty == nr_congested)
+               zone_set_flag(zone, ZONE_CONGESTED);
+
        free_page_list(&free_pages);
 
        list_splice(&ret_pages, page_list);
@@ -1386,12 +1400,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
 
        spin_unlock_irq(&zone->lru_lock);
 
-       nr_reclaimed = shrink_page_list(&page_list, sc);
+       nr_reclaimed = shrink_page_list(&page_list, zone, sc);
 
        /* Check if we should syncronously wait for writeback */
        if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) {
                set_lumpy_reclaim_mode(priority, sc, true);
-               nr_reclaimed += shrink_page_list(&page_list, sc);
+               nr_reclaimed += shrink_page_list(&page_list, zone, sc);
        }
 
        local_irq_disable();
@@ -1982,8 +1996,13 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
 
                /* Take a nap, wait for some writeback to complete */
                if (!sc->hibernation_mode && sc->nr_scanned &&
-                   priority < DEF_PRIORITY - 2)
-                       congestion_wait(BLK_RW_ASYNC, HZ/10);
+                   priority < DEF_PRIORITY - 2) {
+                       struct zone *preferred_zone;
+
+                       first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
+                                                       NULL, &preferred_zone);
+                       wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
+               }
        }
 
 out:
@@ -2282,6 +2301,15 @@ loop_again:
                                if (!zone_watermark_ok(zone, order,
                                            min_wmark_pages(zone), end_zone, 0))
                                        has_under_min_watermark_zone = 1;
+                       } else {
+                               /*
+                                * If a zone reaches its high watermark,
+                                * consider it to be no longer congested. It's
+                                * possible there are dirty pages backed by
+                                * congested BDIs but as pressure is relieved,
+                                * spectulatively avoid congestion waits
+                                */
+                               zone_clear_flag(zone, ZONE_CONGESTED);
                        }
 
                }