mm/mm_init.c: add new function calc_nr_all_pages()

This is a preparation to calculate nr_kernel_pages and nr_all_pages, both
of which will be used later in alloc_large_system_hash().

nr_all_pages counts up all free but not reserved memory in memblock
allocator, including HIGHMEM memory.  While nr_kernel_pages counts up all
free but not reserved low memory in memblock allocator, excluding HIGHMEM
memory.

Link: https://lkml.kernel.org/r/20240325145646.1044760-4-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 91bb8600c0fa2ab69864ec8b41f36d5eb9cf8c5e..ae91499564974eaf4a5e3077a9828e9bb3780464 100644 (file)
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1265,6 +1265,30 @@ static void __init reset_memoryless_node_totalpages(struct pglist_data *pgdat)
        pr_debug("On node %d totalpages: 0\n", pgdat->node_id);
 }
 
+static void __init calc_nr_kernel_pages(void)
+{
+       unsigned long start_pfn, end_pfn;
+       phys_addr_t start_addr, end_addr;
+       u64 u;
+#ifdef CONFIG_HIGHMEM
+       unsigned long high_zone_low = arch_zone_lowest_possible_pfn[ZONE_HIGHMEM];
+#endif
+
+       for_each_free_mem_range(u, NUMA_NO_NODE, MEMBLOCK_NONE, &start_addr, &end_addr, NULL) {
+               start_pfn = PFN_UP(start_addr);
+               end_pfn   = PFN_DOWN(end_addr);
+
+               if (start_pfn < end_pfn) {
+                       nr_all_pages += end_pfn - start_pfn;
+#ifdef CONFIG_HIGHMEM
+                       start_pfn = clamp(start_pfn, 0, high_zone_low);
+                       end_pfn = clamp(end_pfn, 0, high_zone_low);
+#endif
+                       nr_kernel_pages += end_pfn - start_pfn;
+               }
+       }
+}
+
 static void __init calculate_node_totalpages(struct pglist_data *pgdat,
                                                unsigned long node_start_pfn,
                                                unsigned long node_end_pfn)