linux-kernel - [PATCH 07/13] s390: make setup_zero

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Message-ID: <20250306185124.3147510-8-rppt@kernel.org>
Date: Thu,  6 Mar 2025 20:51:17 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
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Subject: [PATCH 07/13] s390: make setup_zero_pages() use memblock

From: "Mike Rapoport (Microsoft)" <rppt@...nel.org>

Allocating the zero pages from memblock is simpler because the memory is
already reserved.

This will also help with pulling out memblock_free_all() to the generic
code and reducing code duplication in arch::mem_init().

Signed-off-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
---
 arch/s390/mm/init.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index f2298f7a3f21..020aa2f78d01 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -73,8 +73,6 @@ static void __init setup_zero_pages(void)
 {
 	unsigned long total_pages = memblock_estimated_nr_free_pages();
 	unsigned int order;
-	struct page *page;
-	int i;
 
 	/* Latest machines require a mapping granularity of 512KB */
 	order = 7;
@@ -83,17 +81,10 @@ static void __init setup_zero_pages(void)
 	while (order > 2 && (total_pages >> 10) < (1UL << order))
 		order--;
 
-	empty_zero_page = __get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
+	empty_zero_page = (unsigned long)memblock_alloc(PAGE_SIZE << order, order);
 	if (!empty_zero_page)
 		panic("Out of memory in setup_zero_pages");
 
-	page = virt_to_page((void *) empty_zero_page);
-	split_page(page, order);
-	for (i = 1 << order; i > 0; i--) {
-		mark_page_reserved(page);
-		page++;
-	}
-
 	zero_page_mask = ((PAGE_SIZE << order) - 1) & PAGE_MASK;
 }
 
@@ -176,9 +167,10 @@ void __init mem_init(void)
 	pv_init();
 	kfence_split_mapping();
 
+	setup_zero_pages();	/* Setup zeroed pages. */
+
 	/* this will put all low memory onto the freelists */
 	memblock_free_all();
-	setup_zero_pages();	/* Setup zeroed pages. */
 }
 
 unsigned long memory_block_size_bytes(void)
-- 
2.47.2