[PATCH 1/2] mm: extract common code for calculating total memory size

[Yang Shi]

Total memory size is needed by unreclaimable slub oom to check if
significant memory is used by a single slab. But, the caculation work is
done in show_mem(), so extracting the common code in order to share with
others.

Signed-off-by: Yang Shi <yan...@alibaba-inc.com>
---
 include/linux/mm.h | 25 +++++++++++++++++++++++++
 lib/show_mem.c     | 20 +-------------------
 2 files changed, 26 insertions(+), 19 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 935c4d4..e21b81e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2050,6 +2050,31 @@ extern int __meminit __early_pfn_to_nid(unsigned long 
pfn,
 static inline void zero_resv_unavail(void) {}
 #endif
 
+static inline void calc_mem_size(unsigned long *total, unsigned long *reserved,
+                                unsigned long *highmem)
+{
+       pg_data_t *pgdat;
+
+       for_each_online_pgdat(pgdat) {
+               unsigned long flags;
+               int zoneid;
+
+               pgdat_resize_lock(pgdat, &flags);
+               for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
+                       struct zone *zone = &pgdat->node_zones[zoneid];
+                       if (!populated_zone(zone))
+                               continue;
+
+                       *total += zone->present_pages;
+                       *reserved += zone->present_pages - zone->managed_pages;
+
+                       if (is_highmem_idx(zoneid))
+                               *highmem += zone->present_pages;
+               }
+               pgdat_resize_unlock(pgdat, &flags);
+       }
+}
+
 extern void set_dma_reserve(unsigned long new_dma_reserve);
 extern void memmap_init_zone(unsigned long, int, unsigned long,
                                unsigned long, enum memmap_context);
diff --git a/lib/show_mem.c b/lib/show_mem.c
index 0beaa1d..115475e 100644
--- a/lib/show_mem.c
+++ b/lib/show_mem.c
@@ -11,30 +11,12 @@
 
 void show_mem(unsigned int filter, nodemask_t *nodemask)
 {
-       pg_data_t *pgdat;
        unsigned long total = 0, reserved = 0, highmem = 0;
 
        printk("Mem-Info:\n");
        show_free_areas(filter, nodemask);
 
-       for_each_online_pgdat(pgdat) {
-               unsigned long flags;
-               int zoneid;
-
-               pgdat_resize_lock(pgdat, &flags);
-               for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
-                       struct zone *zone = &pgdat->node_zones[zoneid];
-                       if (!populated_zone(zone))
-                               continue;
-
-                       total += zone->present_pages;
-                       reserved += zone->present_pages - zone->managed_pages;
-
-                       if (is_highmem_idx(zoneid))
-                               highmem += zone->present_pages;
-               }
-               pgdat_resize_unlock(pgdat, &flags);
-       }
+       calc_mem_size(&total, &reserved, &highmem);
 
        printk("%lu pages RAM\n", total);
        printk("%lu pages HighMem/MovableOnly\n", highmem);
-- 
1.8.3.1