mm,vmscan: fix divide by zero in get_scan_count

[linux-2.6-microblaze.git] / mm / page_reporting.c

diff --git a/mm/page_reporting.c b/mm/page_reporting.c
index c50d93f..382958e 100644 (file)
--- a/mm/page_reporting.c
+++ b/mm/page_reporting.c
@@ -4,12 +4,17 @@
 #include <linux/page_reporting.h>
 #include <linux/gfp.h>
 #include <linux/export.h>
+#include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/scatterlist.h>
 
 #include "page_reporting.h"
 #include "internal.h"
 
+unsigned int page_reporting_order = MAX_ORDER;
+module_param(page_reporting_order, uint, 0644);
+MODULE_PARM_DESC(page_reporting_order, "Set page reporting order");
+
 #define PAGE_REPORTING_DELAY   (2 * HZ)
 static struct page_reporting_dev_info __rcu *pr_dev_info __read_mostly;
 
@@ -31,8 +36,8 @@ __page_reporting_request(struct page_reporting_dev_info *prdev)
                return;
 
        /*
-        *  If reporting is already active there is nothing we need to do.
-        *  Test against 0 as that represents PAGE_REPORTING_IDLE.
+        * If reporting is already active there is nothing we need to do.
+        * Test against 0 as that represents PAGE_REPORTING_IDLE.
         */
        state = atomic_xchg(&prdev->state, PAGE_REPORTING_REQUESTED);
        if (state != PAGE_REPORTING_IDLE)
@@ -229,7 +234,7 @@ page_reporting_process_zone(struct page_reporting_dev_info *prdev,
 
        /* Generate minimum watermark to be able to guarantee progress */
        watermark = low_wmark_pages(zone) +
-                   (PAGE_REPORTING_CAPACITY << PAGE_REPORTING_MIN_ORDER);
+                   (PAGE_REPORTING_CAPACITY << page_reporting_order);
 
        /*
         * Cancel request if insufficient free memory or if we failed
@@ -239,7 +244,7 @@ page_reporting_process_zone(struct page_reporting_dev_info *prdev,
                return err;
 
        /* Process each free list starting from lowest order/mt */
-       for (order = PAGE_REPORTING_MIN_ORDER; order < MAX_ORDER; order++) {
+       for (order = page_reporting_order; order < MAX_ORDER; order++) {
                for (mt = 0; mt < MIGRATE_TYPES; mt++) {
                        /* We do not pull pages from the isolate free list */
                        if (is_migrate_isolate(mt))
@@ -324,6 +329,12 @@ int page_reporting_register(struct page_reporting_dev_info *prdev)
                goto err_out;
        }
 
+       /*
+        * Update the page reporting order if it's specified by driver.
+        * Otherwise, it falls back to @pageblock_order.
+        */
+       page_reporting_order = prdev->order ? : pageblock_order;
+
        /* initialize state and work structures */
        atomic_set(&prdev->state, PAGE_REPORTING_IDLE);
        INIT_DELAYED_WORK(&prdev->work, &page_reporting_process);