[PATCH] s390/mm: get total ram pages from memblock

[Wei Yang <richard.weiyang@gmail.com>]

On s390, zero page's size relies on total ram pages.

Since we plan to move the accounting into __free_pages_core(),
totalram_pages may not represent the total usable pages on system
at this point when defer_init is enabled.

We can get the total usable pages from memblock directly. The size maybe
not accurate due to the alignment, but enough for the calculation.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
CC: Mike Rapoport (IBM) <rppt@kernel.org>
CC: David Hildenbrand <david@redhat.com>

---
Not tested on a machine, hope it is fine.
---
 arch/s390/mm/init.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index e769d2726f4e..d811ffa5e147 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -65,12 +65,13 @@ static void __init setup_zero_pages(void)
 	unsigned int order;
 	struct page *page;
 	int i;
+	unsigned long total_pages = PHYS_PFN(memblock_phys_mem_size() - memblock_reserved_size());
 
 	/* Latest machines require a mapping granularity of 512KB */
 	order = 7;
 
 	/* Limit number of empty zero pages for small memory sizes */
-	while (order > 2 && (totalram_pages() >> 10) < (1UL << order))
+	while (order > 2 && (total_pages >> 10) < (1UL << order))
 		order--;
 
 	empty_zero_page = __get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
-- 
2.34.1