linux-kernel - [PATCH] sparc: Use vmemmap_populate_hugepages for vmemmap

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Message-ID: <20251217120858.18713-1-pilgrimtao@gmail.com>
Date: Wed, 17 Dec 2025 20:08:58 +0800
From: chengkaitao <pilgrimtao@...il.com>
To: davem@...emloft.net,
	andreas@...sler.com,
	akpm@...ux-foundation.org,
	david@...nel.org,
	lorenzo.stoakes@...cle.com,
	Liam.Howlett@...cle.com,
	vbabka@...e.cz,
	rppt@...nel.org,
	surenb@...gle.com,
	mhocko@...e.com
Cc: kevin.brodsky@....com,
	dave.hansen@...ux.intel.com,
	ziy@...dia.com,
	chengkaitao@...inos.cn,
	willy@...radead.org,
	zhengqi.arch@...edance.com,
	sparclinux@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCH] sparc: Use vmemmap_populate_hugepages for vmemmap_populate

From: Chengkaitao <chengkaitao@...inos.cn>

1. Added the vmemmap_false_pmd function to accommodate architectures
that do not support basepages.
2. In the SPARC architecture, reimplemented vmemmap_populate using
vmemmap_populate_hugepages.

Signed-off-by: Chengkaitao <chengkaitao@...inos.cn>
---
 arch/sparc/mm/init_64.c | 56 ++++++++++++++++-------------------------
 include/linux/mm.h      |  1 +
 mm/sparse-vmemmap.c     |  7 +++++-
 3 files changed, 28 insertions(+), 36 deletions(-)

diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index df9f7c444c39..a80cdfa6ba98 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -5,7 +5,7 @@
  *  Copyright (C) 1996-1999 David S. Miller (davem@...p.rutgers.edu)
  *  Copyright (C) 1997-1999 Jakub Jelinek (jj@...site.mff.cuni.cz)
  */
- 
+
 #include <linux/extable.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
@@ -2397,11 +2397,11 @@ void __init paging_init(void)
 	 * work.
 	 */
 	init_mm.pgd += ((shift) / (sizeof(pgd_t)));
-	
+
 	memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
 
 	inherit_prom_mappings();
-	
+
 	/* Ok, we can use our TLB miss and window trap handlers safely.  */
 	setup_tba();
 
@@ -2581,8 +2581,8 @@ unsigned long _PAGE_CACHE __read_mostly;
 EXPORT_SYMBOL(_PAGE_CACHE);
 
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
-int __meminit vmemmap_populate(unsigned long vstart, unsigned long vend,
-			       int node, struct vmem_altmap *altmap)
+void __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node,
+			       unsigned long addr, unsigned long next)
 {
 	unsigned long pte_base;
 
@@ -2595,39 +2595,25 @@ int __meminit vmemmap_populate(unsigned long vstart, unsigned long vend,
 
 	pte_base |= _PAGE_PMD_HUGE;
 
-	vstart = vstart & PMD_MASK;
-	vend = ALIGN(vend, PMD_SIZE);
-	for (; vstart < vend; vstart += PMD_SIZE) {
-		pgd_t *pgd = vmemmap_pgd_populate(vstart, node);
-		unsigned long pte;
-		p4d_t *p4d;
-		pud_t *pud;
-		pmd_t *pmd;
-
-		if (!pgd)
-			return -ENOMEM;
-
-		p4d = vmemmap_p4d_populate(pgd, vstart, node);
-		if (!p4d)
-			return -ENOMEM;
-
-		pud = vmemmap_pud_populate(p4d, vstart, node);
-		if (!pud)
-			return -ENOMEM;
-
-		pmd = pmd_offset(pud, vstart);
-		pte = pmd_val(*pmd);
-		if (!(pte & _PAGE_VALID)) {
-			void *block = vmemmap_alloc_block(PMD_SIZE, node);
+	pmd_val(*pmd) = pte_base | __pa(p);
+}
 
-			if (!block)
-				return -ENOMEM;
+bool __meminit vmemmap_false_pmd(pmd_t *pmd, int node)
+{
+	return true;
+}
 
-			pmd_val(*pmd) = pte_base | __pa(block);
-		}
-	}
+int __meminit vmemmap_check_pmd(pmd_t *pmdp, int node,
+				unsigned long addr, unsigned long next)
+{
+	vmemmap_verify((pte_t *)pmdp, node, addr, next);
+	return 1;
+}
 
-	return 0;
+int __meminit vmemmap_populate(unsigned long vstart, unsigned long vend,
+			       int node, struct vmem_altmap *altmap)
+{
+	return vmemmap_populate_hugepages(vstart, vend, node, altmap);
 }
 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 15076261d0c2..5e005b0f947d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4248,6 +4248,7 @@ void *vmemmap_alloc_block_buf(unsigned long size, int node,
 void vmemmap_verify(pte_t *, int, unsigned long, unsigned long);
 void vmemmap_set_pmd(pmd_t *pmd, void *p, int node,
 		     unsigned long addr, unsigned long next);
+bool vmemmap_false_pmd(pmd_t *pmd, int node);
 int vmemmap_check_pmd(pmd_t *pmd, int node,
 		      unsigned long addr, unsigned long next);
 int vmemmap_populate_basepages(unsigned long start, unsigned long end,
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 37522d6cb398..bd54b8c6f56e 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -407,6 +407,11 @@ void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node,
 {
 }
 
+bool __weak __meminit vmemmap_false_pmd(pmd_t *pmd, int node)
+{
+	return 0;
+}
+
 int __weak __meminit vmemmap_check_pmd(pmd_t *pmd, int node,
 				       unsigned long addr, unsigned long next)
 {
@@ -446,7 +451,7 @@ int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end,
 			if (p) {
 				vmemmap_set_pmd(pmd, p, node, addr, next);
 				continue;
-			} else if (altmap) {
+			} else if (altmap || vmemmap_false_pmd(pmd, node)) {
 				/*
 				 * No fallback: In any case we care about, the
 				 * altmap should be reasonably sized and aligned
-- 
2.50.1 (Apple Git-155)