1 files changed, 22 insertions, 5 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index b7d868cbca09..1b85217b528c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -70,6 +70,13 @@ struct scan_control {
 
         int order;
 
+        /*
+         * Pages that have (or should have) IO pending.  If we run into
+         * a lot of these, we're better off waiting a little for IO to
+         * finish rather than scanning more pages in the VM.
+         */
+        int nr_io_pages;
+
         /* Which cgroup do we reclaim from */
         struct mem_cgroup *mem_cgroup;
 
@@ -499,8 +506,10 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                          */
                         if (sync_writeback == PAGEOUT_IO_SYNC && may_enter_fs)
                                 wait_on_page_writeback(page);
-                        else
+                        else {
+                                sc->nr_io_pages++;
                                 goto keep_locked;
+                        }
                 }
 
                 referenced = page_referenced(page, 1, sc->mem_cgroup);
@@ -539,8 +548,10 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                 if (PageDirty(page)) {
                         if (sc->order <= PAGE_ALLOC_COSTLY_ORDER && referenced)
                                 goto keep_locked;
-                        if (!may_enter_fs)
+                        if (!may_enter_fs) {
+                                sc->nr_io_pages++;
                                 goto keep_locked;
+                        }
                         if (!sc->may_writepage)
                                 goto keep_locked;
 
@@ -551,8 +562,10 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                         case PAGE_ACTIVATE:
                                 goto activate_locked;
                         case PAGE_SUCCESS:
-                                if (PageWriteback(page) || PageDirty(page))
+                                if (PageWriteback(page) || PageDirty(page)) {
+                                        sc->nr_io_pages++;
                                         goto keep;
+                                }
                                 /*
                                  * A synchronous write - probably a ramdisk.  Go
                                  * ahead and try to reclaim the page.
@@ -1259,6 +1272,7 @@ static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
 
         for (priority = DEF_PRIORITY; priority >= 0; priority--) {
                 sc->nr_scanned = 0;
+                sc->nr_io_pages = 0;
                 if (!priority)
                         disable_swap_token();
                 nr_reclaimed += shrink_zones(priority, zones, sc);
@@ -1292,7 +1306,8 @@ static unsigned long do_try_to_free_pages(struct zone **zones, gfp_t gfp_mask,
                 }
 
                 /* Take a nap, wait for some writeback to complete */
-                if (sc->nr_scanned && priority < DEF_PRIORITY - 2)
+                if (sc->nr_scanned && priority < DEF_PRIORITY - 2 &&
+                                sc->nr_io_pages > sc->swap_cluster_max)
                         congestion_wait(WRITE, HZ/10);
         }
         /* top priority shrink_caches still had more to do? don't OOM, then */
@@ -1424,6 +1439,7 @@ loop_again:
                 if (!priority)
                         disable_swap_token();
 
+                sc.nr_io_pages = 0;
                 all_zones_ok = 1;
 
                 /*
@@ -1516,7 +1532,8 @@ loop_again:
                  * OK, kswapd is getting into trouble.  Take a nap, then take
                  * another pass across the zones.
                  */
-                if (total_scanned && priority < DEF_PRIORITY - 2)
+                if (total_scanned && priority < DEF_PRIORITY - 2 &&
+                                        sc.nr_io_pages > sc.swap_cluster_max)
                         congestion_wait(WRITE, HZ/10);
 
                 /*