diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 688abc6..7a96623 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -62,7 +62,7 @@ EXPORT_SYMBOL(zero_page_mask);
 
 static void __init setup_zero_pages(void)
 {
-	unsigned long total_pages = PHYS_PFN(memblock_phys_mem_size() - memblock_reserved_size());
+	unsigned long total_pages = memblock_estimated_nr_free_pages();
 	unsigned int order;
 	struct page *page;
 	int i;
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index fc4d75c..673d5ca 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -467,6 +467,7 @@ static inline __init_memblock bool memblock_bottom_up(void)
 
 phys_addr_t memblock_phys_mem_size(void);
 phys_addr_t memblock_reserved_size(void);
+unsigned long memblock_estimated_nr_free_pages(void);
 phys_addr_t memblock_start_of_DRAM(void);
 phys_addr_t memblock_end_of_DRAM(void);
 void memblock_enforce_memory_limit(phys_addr_t memory_limit);
diff --git a/kernel/fork.c b/kernel/fork.c
index cbdaca4..60c0b48 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -999,7 +999,7 @@ void __init __weak arch_task_cache_init(void) { }
 static void __init set_max_threads(unsigned int max_threads_suggested)
 {
 	u64 threads;
-	unsigned long nr_pages = PHYS_PFN(memblock_phys_mem_size() - memblock_reserved_size());
+	unsigned long nr_pages = memblock_estimated_nr_free_pages();
 
 	/*
 	 * The number of threads shall be limited such that the thread
diff --git a/mm/memblock.c b/mm/memblock.c
index 0a77a74..0389ce5 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1731,6 +1731,23 @@ phys_addr_t __init_memblock memblock_reserved_size(void)
 	return memblock.reserved.total_size;
 }
 
+/**
+ * memblock_estimated_nr_free_pages - return estimated number of free pages
+ * from memblock point of view
+ *
+ * During bootup, subsystems might need a rough estimate of the number of free
+ * pages in the whole system, before precise numbers are available from the
+ * buddy. Especially with CONFIG_DEFERRED_STRUCT_PAGE_INIT, the numbers
+ * obtained from the buddy might be very imprecise during bootup.
+ *
+ * Return:
+ * An estimated number of free pages from memblock point of view.
+ */
+unsigned long __init memblock_estimated_nr_free_pages(void)
+{
+	return PHYS_PFN(memblock_phys_mem_size() - memblock_reserved_size());
+}
+
 /* lowest address */
 phys_addr_t __init_memblock memblock_start_of_DRAM(void)
 {
diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 4366da2..9c05a59 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -128,10 +128,6 @@
 # define unlikely(x)		__builtin_expect(!!(x), 0)
 #endif
 
-#ifndef __init
-# define __init
-#endif
-
 #include <linux/types.h>
 
 /*
diff --git a/tools/testing/memblock/linux/init.h b/tools/include/linux/init.h
similarity index 76%
rename from tools/testing/memblock/linux/init.h
rename to tools/include/linux/init.h
index 828e0ee..51b5cde 100644
--- a/tools/testing/memblock/linux/init.h
+++ b/tools/include/linux/init.h
@@ -1,10 +1,16 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _LINUX_INIT_H
-#define _LINUX_INIT_H
+#ifndef _TOOLS_LINUX_INIT_H_
+#define _TOOLS_LINUX_INIT_H_
 
 #include <linux/compiler.h>
-#include <asm/export.h>
-#include <linux/memory_hotplug.h>
+
+#ifndef __init
+# define __init
+#endif
+
+#ifndef __exit
+# define __exit
+#endif
 
 #define __section(section)              __attribute__((__section__(section)))
 
@@ -28,7 +34,10 @@ struct obs_kernel_param {
 		__aligned(__alignof__(struct obs_kernel_param)) =	\
 		{ __setup_str_##unique_id, fn, early }
 
+#define __setup(str, fn)						\
+	__setup_param(str, fn, fn, 0)
+
 #define early_param(str, fn)						\
 	__setup_param(str, fn, fn, 1)
 
-#endif
+#endif /*  _TOOLS_LINUX_INIT_H_ */
diff --git a/tools/include/linux/linkage.h b/tools/include/linux/linkage.h
index a48ff08..b718357 100644
--- a/tools/include/linux/linkage.h
+++ b/tools/include/linux/linkage.h
@@ -1,6 +1,8 @@
 #ifndef _TOOLS_INCLUDE_LINUX_LINKAGE_H
 #define _TOOLS_INCLUDE_LINUX_LINKAGE_H
 
+#include <linux/export.h>
+
 #define SYM_FUNC_START(x) .globl x; x:
 
 #define SYM_FUNC_END(x)
diff --git a/tools/include/linux/mm.h b/tools/include/linux/mm.h
index cad4f29..677c37e 100644
--- a/tools/include/linux/mm.h
+++ b/tools/include/linux/mm.h
@@ -25,6 +25,12 @@ static inline void *phys_to_virt(unsigned long address)
 	return __va(address);
 }
 
+#define virt_to_phys virt_to_phys
+static inline phys_addr_t virt_to_phys(volatile void *address)
+{
+	return (phys_addr_t)address;
+}
+
 void reserve_bootmem_region(phys_addr_t start, phys_addr_t end, int nid);
 
 static inline void totalram_pages_inc(void)
diff --git a/tools/include/linux/pfn.h b/tools/include/linux/pfn.h
index 7512a58..f77a30d 100644
--- a/tools/include/linux/pfn.h
+++ b/tools/include/linux/pfn.h
@@ -7,4 +7,5 @@
 #define PFN_UP(x)	(((x) + PAGE_SIZE - 1) >> PAGE_SHIFT)
 #define PFN_DOWN(x)	((x) >> PAGE_SHIFT)
 #define PFN_PHYS(x)	((phys_addr_t)(x) << PAGE_SHIFT)
+#define PHYS_PFN(x)	((unsigned long)((x) >> PAGE_SHIFT))
 #endif
diff --git a/tools/include/linux/string.h b/tools/include/linux/string.h
index 0acb1fc..8499f50 100644
--- a/tools/include/linux/string.h
+++ b/tools/include/linux/string.h
@@ -12,6 +12,8 @@ void argv_free(char **argv);
 
 int strtobool(const char *s, bool *res);
 
+#define strscpy strcpy
+
 /*
  * glibc based builds needs the extern while uClibc doesn't.
  * However uClibc headers also define __GLIBC__ hence the hack below
@@ -49,4 +51,5 @@ extern char *strim(char *);
 extern void remove_spaces(char *s);
 
 extern void *memchr_inv(const void *start, int c, size_t bytes);
+extern unsigned long long memparse(const char *ptr, char **retptr);
 #endif /* _TOOLS_LINUX_STRING_H_ */
diff --git a/tools/lib/cmdline.c b/tools/lib/cmdline.c
new file mode 100644
index 0000000..c85f00f
--- /dev/null
+++ b/tools/lib/cmdline.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * From lib/cmdline.c
+ */
+#include <stdlib.h>
+
+#if __has_attribute(__fallthrough__)
+# define fallthrough                    __attribute__((__fallthrough__))
+#else
+# define fallthrough                    do {} while (0)  /* fallthrough */
+#endif
+
+unsigned long long memparse(const char *ptr, char **retptr)
+{
+	char *endptr;	/* local pointer to end of parsed string */
+
+	unsigned long long ret = strtoll(ptr, &endptr, 0);
+
+	switch (*endptr) {
+	case 'E':
+	case 'e':
+		ret <<= 10;
+		fallthrough;
+	case 'P':
+	case 'p':
+		ret <<= 10;
+		fallthrough;
+	case 'T':
+	case 't':
+		ret <<= 10;
+		fallthrough;
+	case 'G':
+	case 'g':
+		ret <<= 10;
+		fallthrough;
+	case 'M':
+	case 'm':
+		ret <<= 10;
+		fallthrough;
+	case 'K':
+	case 'k':
+		ret <<= 10;
+		endptr++;
+		fallthrough;
+	default:
+		break;
+	}
+
+	if (retptr)
+		*retptr = endptr;
+
+	return ret;
+}
diff --git a/tools/testing/memblock/Makefile b/tools/testing/memblock/Makefile
index 7a1ca69..d80982c 100644
--- a/tools/testing/memblock/Makefile
+++ b/tools/testing/memblock/Makefile
@@ -8,7 +8,7 @@ LDFLAGS += -fsanitize=address -fsanitize=undefined
 TARGETS = main
 TEST_OFILES = tests/alloc_nid_api.o tests/alloc_helpers_api.o tests/alloc_api.o \
 		  tests/basic_api.o tests/common.o tests/alloc_exact_nid_api.o
-DEP_OFILES = memblock.o lib/slab.o mmzone.o slab.o
+DEP_OFILES = memblock.o lib/slab.o mmzone.o slab.o cmdline.o
 OFILES = main.o $(DEP_OFILES) $(TEST_OFILES)
 EXTR_SRC = ../../../mm/memblock.c
 
diff --git a/tools/testing/memblock/linux/kernel.h b/tools/testing/memblock/linux/kernel.h
index d2f148b..4d1012d 100644
--- a/tools/testing/memblock/linux/kernel.h
+++ b/tools/testing/memblock/linux/kernel.h
@@ -8,5 +8,7 @@
 #include <linux/printk.h>
 #include <linux/linkage.h>
 #include <linux/kconfig.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
 
 #endif
diff --git a/tools/testing/memblock/linux/mmzone.h b/tools/testing/memblock/linux/mmzone.h
index 71546e1..bb68265 100644
--- a/tools/testing/memblock/linux/mmzone.h
+++ b/tools/testing/memblock/linux/mmzone.h
@@ -3,6 +3,7 @@
 #define _TOOLS_MMZONE_H
 
 #include <linux/atomic.h>
+#include <linux/memory_hotplug.h>
 
 struct pglist_data *first_online_pgdat(void);
 struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
index c5b00ac..1873ddb 100644
--- a/tools/testing/radix-tree/maple.c
+++ b/tools/testing/radix-tree/maple.c
@@ -14,7 +14,7 @@
 #include "test.h"
 #include <stdlib.h>
 #include <time.h>
-#include "linux/init.h"
+#include <linux/init.h>
 
 #define module_init(x)
 #define module_exit(x)
diff --git a/tools/testing/shared/linux/init.h b/tools/testing/shared/linux/init.h
deleted file mode 100644
index 81563c3..0000000
--- a/tools/testing/shared/linux/init.h
+++ /dev/null
@@ -1,2 +0,0 @@
-#define __init
-#define __exit