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

[Muchun Song <songmuchun@bytedance.com>]

Whether the optimized mapping can be used is now decided in the
architecture-specific vmemmap_populate() path. When PowerPC has to fall
back, such as on Hash MMU, it can disable optimization for the populated
vmemmap range there.

Add section_vmemmap_optimization_disable() to centralize this fallback,
use it in the Hash MMU path, and drop the radix-specific
vmemmap_can_optimize() override.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
v2:
- Add section_vmemmap_optimization_disable() for architecture fallbacks
- Use the helper for the PowerPC Hash MMU path
- Include vmemmap-optimization.h directly (reported by Sashiko)
---
 arch/powerpc/include/asm/book3s/64/radix.h |  5 ----
 arch/powerpc/mm/book3s64/radix_pgtable.c   | 10 -------
 arch/powerpc/mm/init_64.c                  |  2 ++
 include/linux/vmemmap-optimization.h       | 31 ++++++++++++++++++++++
 mm/sparse.h                                |  5 ----
 5 files changed, 33 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
index 8452a2714cb1..df67209b0c5b 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -351,10 +351,5 @@ int radix__create_section_mapping(unsigned long start, unsigned long end,
 				  int nid, pgprot_t prot);
 int radix__remove_section_mapping(unsigned long start, unsigned long end);
 #endif /* CONFIG_MEMORY_HOTPLUG */
-
-#ifdef CONFIG_ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
-#define vmemmap_can_optimize vmemmap_can_optimize
-bool vmemmap_can_optimize(struct vmem_altmap *altmap, struct dev_pagemap *pgmap);
-#endif
 #endif /* __ASSEMBLER__ */
 #endif
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index 2924604fbb38..63f369d296b4 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -978,16 +978,6 @@ int __meminit radix__vmemmap_create_mapping(unsigned long start,
 	return 0;
 }
 
-#ifdef CONFIG_ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
-bool vmemmap_can_optimize(struct vmem_altmap *altmap, struct dev_pagemap *pgmap)
-{
-	if (radix_enabled())
-		return __vmemmap_can_optimize(altmap, pgmap);
-
-	return false;
-}
-#endif
-
 int __meminit vmemmap_check_pmd(pmd_t *pmdp, int node,
 				unsigned long addr, unsigned long next)
 {
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 0e777d7dc332..4d6928f717cf 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -24,6 +24,7 @@
 #include <linux/types.h>
 #include <linux/mman.h>
 #include <linux/mm.h>
+#include <linux/vmemmap-optimization.h>
 #include <linux/swap.h>
 #include <linux/stddef.h>
 #include <linux/vmalloc.h>
@@ -282,6 +283,7 @@ 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);
 	return __vmemmap_populate(start, end, node, altmap);
 }
 
diff --git a/include/linux/vmemmap-optimization.h b/include/linux/vmemmap-optimization.h
index 858311a71b0c..5c09da4df4d8 100644
--- a/include/linux/vmemmap-optimization.h
+++ b/include/linux/vmemmap-optimization.h
@@ -57,6 +57,27 @@ static inline void section_set_compound_order_range(unsigned long pfn,
 		section_set_compound_order(__nr_to_section(section_nr + i), order);
 }
 
+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)
+{
+	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) {
+		VM_WARN_ON_ONCE(section_vmemmap_optimizable(section));
+		return;
+	}
+
+	VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION));
+	section_set_compound_order(section, 0);
+}
+
 static inline unsigned int pfn_to_section_compound_order(unsigned long pfn)
 {
 	return section_compound_order(__pfn_to_section(pfn));
@@ -79,6 +100,16 @@ static inline void section_set_compound_order_range(unsigned long pfn,
 {
 }
 
+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 unsigned int pfn_to_section_compound_order(unsigned long pfn)
 {
 	return 0;
diff --git a/mm/sparse.h b/mm/sparse.h
index fdbc4cacf91d..9b81a549d928 100644
--- a/mm/sparse.h
+++ b/mm/sparse.h
@@ -46,11 +46,6 @@ static inline size_t mem_section_usage_size(void)
 	return struct_size_t(struct mem_section_usage, pageblock_flags,
 			     BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS));
 }
-
-static inline bool section_vmemmap_optimizable(const struct mem_section *ms)
-{
-	return vmemmap_optimizable_order(section_compound_order(ms));
-}
 #else
 static inline void sparse_init(void) {}
 static inline void sparse_sections_init(void) {}
-- 
2.54.0