Re: [PATCH v2 2/5] powerpc/mm: drop powerpc vmemmap_can_optimize()

[Lance Yang <lance.yang@linux.dev>]

On Thu, Nov 05, 2026 at 07:16:48AM +0000, sashiko-bot@kernel.org wrote:
>Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
>- [Low] mm: undeclared vmemmap in section_vmemmap_optimization_disable()
>- [Low] mm: define vmemmap_optimizable_order() before section_vmemmap_optimizable()
>--

IIUC, on LoongArch, asm/pgtable.h includes vmemmap-optimization.h before
defining vmemmap.

How about taking a PFN and page count instead, and leaving the conversion
to the callers?

---8<---
diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
index c91afce46136..5a3a225135be 100644
--- a/arch/loongarch/mm/init.c
+++ b/arch/loongarch/mm/init.c
@@ -143,7 +143,8 @@ void __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node,
 int __meminit vmemmap_populate(unsigned long start, unsigned long end,
 			       int node, struct vmem_altmap *altmap)
 {
-	section_vmemmap_optimization_disable(start, end);
+	section_vmemmap_optimization_disable(page_to_pfn((struct page *)start),
+					     (end - start) / sizeof(struct page));
 #if CONFIG_PGTABLE_LEVELS == 2
 	return vmemmap_populate_basepages(start, end, node, NULL);
 #else
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 4d6928f717cf..43c98aec29aa 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -283,7 +283,8 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 		return radix__vmemmap_populate(start, end, node, altmap);
 #endif
 
-	section_vmemmap_optimization_disable(start, end);
+	section_vmemmap_optimization_disable(page_to_pfn((struct page *)start),
+					     (end - start) / sizeof(struct page));
 	return __vmemmap_populate(start, end, node, altmap);
 }
 
diff --git a/include/linux/vmemmap-optimization.h b/include/linux/vmemmap-optimization.h
index 9d9f7a67d195..0501234ab16b 100644
--- a/include/linux/vmemmap-optimization.h
+++ b/include/linux/vmemmap-optimization.h
@@ -76,11 +76,9 @@ static inline bool section_vmemmap_optimizable(const struct mem_section *section
 	return vmemmap_optimizable_order(section_compound_order(section));
 }
 
-static inline void section_vmemmap_optimization_disable(unsigned long start,
-		unsigned long end)
+static inline void section_vmemmap_optimization_disable(unsigned long pfn,
+							unsigned long nr_pages)
 {
-	unsigned long pfn = page_to_pfn((struct page *)start);
-	unsigned long nr_pages = (end - start) / sizeof(struct page);
 	struct mem_section *section = __pfn_to_section(pfn);
 
 	if (nr_pages < PAGES_PER_SECTION) {
@@ -119,8 +117,8 @@ static inline bool section_vmemmap_optimizable(const struct mem_section *section
 	return false;
 }
 
-static inline void section_vmemmap_optimization_disable(unsigned long start,
-		unsigned long end)
+static inline void section_vmemmap_optimization_disable(unsigned long pfn,
+							unsigned long nr_pages)
 {
 }
 
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 5777f2e29684..64bc346d0fc5 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -474,7 +474,7 @@ struct page * __meminit __populate_section_memmap(unsigned long pfn,
 
 	/* Altmap-backed vmemmap pages cannot be optimized. */
 	if (altmap)
-		section_vmemmap_optimization_disable(start, end);
+		section_vmemmap_optimization_disable(pfn, nr_pages);
 	r = vmemmap_populate(start, end, nid, altmap);
 	if (r < 0)
 		return NULL;
---

Cheers, Lance