@@ -144,7 +144,6 @@ config ARM64
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_MMAP_RND_BITS
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
-	select HAVE_ARCH_PFN_VALID
 	select HAVE_ARCH_PREL32_RELOCATIONS
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_STACKLEAK

@@ -167,6 +166,7 @@ config ARM64
 		if $(cc-option,-fpatchable-function-entry=2)
 	select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY \
 		if DYNAMIC_FTRACE_WITH_REGS
+	select HAVE_EARLY_SECTION_MEMMAP_HOLES
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select HAVE_FAST_GUP
 	select HAVE_FTRACE_MCOUNT_RECORD

@@ -37,7 +37,6 @@ void copy_highpage(struct page *to, struct page *from);
 
 typedef struct page *pgtable_t;
 
-int pfn_valid(unsigned long pfn);
 int pfn_is_map_memory(unsigned long pfn);
 
 #include <asm/memory.h>

@@ -217,47 +217,6 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
 	free_area_init(max_zone_pfns);
 }
 
-int pfn_valid(unsigned long pfn)
-{
-	phys_addr_t addr = PFN_PHYS(pfn);
-
-	/*
-	 * Ensure the upper PAGE_SHIFT bits are clear in the
-	 * pfn. Else it might lead to false positives when
-	 * some of the upper bits are set, but the lower bits
-	 * match a valid pfn.
-	 */
-	if (PHYS_PFN(addr) != pfn)
-		return 0;
-
-#ifdef CONFIG_SPARSEMEM
-{
-	struct mem_section *ms;
-
-	if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
-		return 0;
-
-	ms = __pfn_to_section(pfn);
-	if (!valid_section(ms))
-		return 0;
-
-	/*
-	 * ZONE_DEVICE memory does not have the memblock entries.
-	 * memblock_is_memory() check for ZONE_DEVICE based
-	 * addresses will always fail. Even the normal hotplugged
-	 * memory will never have MEMBLOCK_NOMAP flag set in their
-	 * memblock entries. Skip memblock search for all non early
-	 * memory sections covering all of hotplug memory including
-	 * both normal and ZONE_DEVICE based.
-	 */
-	if (!early_section(ms))
-		return pfn_section_valid(ms, pfn);
-}
-#endif
-	return memblock_is_memory(addr);
-}
-EXPORT_SYMBOL(pfn_valid);
-
 int pfn_is_map_memory(unsigned long pfn)
 {
 	phys_addr_t addr = PFN_PHYS(pfn);

@@ -1421,10 +1421,22 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)
  *
  * Return: 1 for PFNs that have memory map entries and 0 otherwise
  */
+bool memblock_is_memory(phys_addr_t addr);
+
 static inline int pfn_valid(unsigned long pfn)
 {
+	phys_addr_t addr = PFN_PHYS(pfn);
 	struct mem_section *ms;
 
+	/*
+	 * Ensure the upper PAGE_SHIFT bits are clear in the
+	 * pfn. Else it might lead to false positives when
+	 * some of the upper bits are set, but the lower bits
+	 * match a valid pfn.
+	 */
+	if (PHYS_PFN(addr) != pfn)
+		return 0;
+
 	if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
 		return 0;
 	ms = __nr_to_section(pfn_to_section_nr(pfn));

@@ -1434,7 +1446,11 @@ static inline int pfn_valid(unsigned long pfn)
 	 * Traditionally early sections always returned pfn_valid() for
 	 * the entire section-sized span.
 	 */
-	return early_section(ms) || pfn_section_valid(ms, pfn);
+	if (early_section(ms))
+		return IS_ENABLED(CONFIG_HAVE_EARLY_SECTION_MEMMAP_HOLES) ?
+			memblock_is_memory(pfn << PAGE_SHIFT) : 1;
+
+	return pfn_section_valid(ms, pfn);
 }
 #endif
 

@@ -135,6 +135,15 @@ config HAVE_FAST_GUP
 config ARCH_KEEP_MEMBLOCK
 	bool
 
+config HAVE_EARLY_SECTION_MEMMAP_HOLES
+	depends on ARCH_KEEP_MEMBLOCK && SPARSEMEM_VMEMMAP
+	def_bool n
+	help
+	  Early sections on certain platforms might have some memory ranges that
+	  are not backed with struct page mappings. When subscribed, this option
+	  enables special handling for those memory ranges in certain situations
+	  such as pfn_valid().
+
 # Keep arch NUMA mapping infrastructure post-init.
 config NUMA_KEEP_MEMINFO
 	bool

@@ -1740,6 +1740,7 @@ bool __init_memblock memblock_is_memory(phys_addr_t addr)
 {
 	return memblock_search(&memblock.memory, addr) != -1;
 }
+EXPORT_SYMBOL(memblock_is_memory);
 
 bool __init_memblock memblock_is_map_memory(phys_addr_t addr)
 {

@@ -1931,8 +1932,11 @@ static void __init free_unused_memmap(void)
 	unsigned long start, end, prev_end = 0;
 	int i;
 
-	if (!IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID) ||
-	    IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
+	if (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
+		return;
+
+	if (!IS_ENABLED(CONFIG_HAVE_EARLY_SECTION_MEMMAP_HOLES) &&
+	    !IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID))
 		return;
 
 	/*

@@ -309,6 +309,11 @@ struct page *pfn_to_online_page(unsigned long pfn)
 	 * Save some code text when online_section() +
 	 * pfn_section_valid() are sufficient.
 	 */
+	if (IS_ENABLED(CONFIG_HAVE_EARLY_SECTION_MEMMAP_HOLES)) {
+		if (early_section(ms) && !memblock_is_memory(PFN_PHYS(pfn)))
+			return NULL;
+	}
+
 	if (IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID) && !pfn_valid(pfn))
 		return NULL;