mm/mm_init.c: introduce reset_memoryless_node_totalpages()

Currently, no matter whether a node actually has memory or not,
calculate_node_totalpages() is used to account number of pages in
zone/node.  However, for node without memory, these unnecessary
calculations can be skipped.  All the zone/node page counts can be set to
0 directly.  So introduce reset_memoryless_node_totalpages() to perform
this action.

Furthermore, calculate_node_totalpages() only gets called for the node
with memory.

Link: https://lkml.kernel.org/r/20230526085251.1977-1-haifeng.xu@shopee.com
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Suggested-by: Mike Rapoport <rppt@kernel.org>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 10bf560..6f7da39 100644 (file)
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1176,10 +1176,6 @@ static unsigned long __init zone_absent_pages_in_node(int nid,
        unsigned long zone_start_pfn, zone_end_pfn;
        unsigned long nr_absent;
 
-       /* When hotadd a new node from cpu_up(), the node should be empty */
-       if (!node_start_pfn && !node_end_pfn)
-               return 0;
-
        zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
        zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
 
@@ -1229,9 +1225,6 @@ static unsigned long __init zone_spanned_pages_in_node(int nid,
 {
        unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
        unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
-       /* When hotadd a new node from cpu_up(), the node should be empty */
-       if (!node_start_pfn && !node_end_pfn)
-               return 0;
 
        /* Get the start and end of the zone */
        *zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
@@ -1252,6 +1245,24 @@ static unsigned long __init zone_spanned_pages_in_node(int nid,
        return *zone_end_pfn - *zone_start_pfn;
 }
 
+static void __init reset_memoryless_node_totalpages(struct pglist_data *pgdat)
+{
+       struct zone *z;
+
+       for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++) {
+               z->zone_start_pfn = 0;
+               z->spanned_pages = 0;
+               z->present_pages = 0;
+#if defined(CONFIG_MEMORY_HOTPLUG)
+               z->present_early_pages = 0;
+#endif
+       }
+
+       pgdat->node_spanned_pages = 0;
+       pgdat->node_present_pages = 0;
+       pr_debug("On node %d totalpages: 0\n", pgdat->node_id);
+}
+
 static void __init calculate_node_totalpages(struct pglist_data *pgdat,
                                                unsigned long node_start_pfn,
                                                unsigned long node_end_pfn)
@@ -1704,11 +1715,13 @@ static void __init free_area_init_node(int nid)
                pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid,
                        (u64)start_pfn << PAGE_SHIFT,
                        end_pfn ? ((u64)end_pfn << PAGE_SHIFT) - 1 : 0);
+
+               calculate_node_totalpages(pgdat, start_pfn, end_pfn);
        } else {
                pr_info("Initmem setup node %d as memoryless\n", nid);
-       }
 
-       calculate_node_totalpages(pgdat, start_pfn, end_pfn);
+               reset_memoryless_node_totalpages(pgdat);
+       }
 
        alloc_node_mem_map(pgdat);
        pgdat_set_deferred_range(pgdat);