On 10/14/2016 05:03 AM, js1...@gmail.com wrote:
@@ -145,6 +145,35 @@ static int __init cma_activate_area(struct cma *cma)
 static int __init cma_init_reserved_areas(void)
 {
        int i;
+       struct zone *zone;
+       pg_data_t *pgdat;
+
+       if (!cma_area_count)
+               return 0;
+
+       for_each_online_pgdat(pgdat) {
+               unsigned long start_pfn = UINT_MAX, end_pfn = 0;
+
+               for (i = 0; i < cma_area_count; i++) {
+                       if (pfn_to_nid(cma_areas[i].base_pfn) !=
+                               pgdat->node_id)
+                               continue;
+
+                       start_pfn = min(start_pfn, cma_areas[i].base_pfn);
+                       end_pfn = max(end_pfn, cma_areas[i].base_pfn +
+                                               cma_areas[i].count);
+               }
+
+               if (!end_pfn)
+                       continue;
+
+               zone = &pgdat->node_zones[ZONE_CMA];
+
+               /* ZONE_CMA doesn't need to exceed CMA region */
+               zone->zone_start_pfn = max(zone->zone_start_pfn, start_pfn);
+               zone->spanned_pages = min(zone_end_pfn(zone), end_pfn) -
+                                       zone->zone_start_pfn;


Hmm, do the max/min here work as intended? IIUC the initial zone_start_pfn is UINT_MAX and zone->spanned_pages is 1? So at least the max/min should be swapped? Also the zone_end_pfn(zone) on the second line already sees the changes to zone->zone_start_pfn in the first line, so it's kind of a mess. You should probably cache zone_end_pfn() to a temporary variable before changing zone_start_pfn.

+       }

I'm guessing the initial values come from this part in patch 2/6:

@@ -5723,6 +5738,8 @@ static void __meminit calculate_node_totalpages(struct 
pglist_data *pgdat,
                                                unsigned long *zholes_size)
 {
        unsigned long realtotalpages = 0, totalpages = 0;
+       unsigned long zone_cma_start_pfn = UINT_MAX;
+       unsigned long zone_cma_end_pfn = 0;
        enum zone_type i;

        for (i = 0; i < MAX_NR_ZONES; i++) {
@@ -5730,6 +5747,13 @@ static void __meminit calculate_node_totalpages(struct 
pglist_data *pgdat,
                unsigned long zone_start_pfn, zone_end_pfn;
                unsigned long size, real_size;

+               if (is_zone_cma_idx(i)) {
+                       zone->zone_start_pfn = zone_cma_start_pfn;
+                       size = zone_cma_end_pfn - zone_cma_start_pfn;
+                       real_size = 0;
+                       goto init_zone;
+               }

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