[PATCH v4 06/15] linux/mm.h: move page_address() and others to mm/page_address.h

[Max Kellermann]

Prepare to reduce dependencies on linux/mm.h.

page_address() is used by the following popular headers:

- linux/bio.h
- linux/bvec.h
- linux/highmem.h
- linux/scatterlist.h
- linux/skbuff.h

Moving it to a separate lean header will allow us to avoid the
dependency on linux/mm.h.

Signed-off-by: Max Kellermann <max.kellermann@xxxxxxxxx>
---
 include/linux/mm.h              | 56 +-------------------------
 include/linux/mm/page_address.h | 71 +++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+), 55 deletions(-)
 create mode 100644 include/linux/mm/page_address.h

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 79c1f924d4b5..713cedc03b88 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2,7 +2,7 @@
 #ifndef _LINUX_MM_H
 #define _LINUX_MM_H
 
-#include <linux/mm/page_kasan_tag.h>
+#include <linux/mm/page_address.h>
 #include <linux/mm/page_section.h>
 #include <linux/errno.h>
 #include <linux/mmdebug.h>
@@ -104,10 +104,6 @@ extern int mmap_rnd_compat_bits __read_mostly;
 #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
 #endif
 
-#ifndef page_to_virt
-#define page_to_virt(x)	__va(PFN_PHYS(page_to_pfn(x)))
-#endif
-
 #ifndef lm_alias
 #define lm_alias(x)	__va(__pa_symbol(x))
 #endif
@@ -211,14 +207,6 @@ int overcommit_kbytes_handler(struct ctl_table *, int, void *, size_t *,
 int overcommit_policy_handler(struct ctl_table *, int, void *, size_t *,
 		loff_t *);
 
-#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
-#define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n))
-#define folio_page_idx(folio, p)	(page_to_pfn(p) - folio_pfn(folio))
-#else
-#define nth_page(page,n) ((page) + (n))
-#define folio_page_idx(folio, p)	((p) - &(folio)->page)
-#endif
-
 /* to align the pointer to the (next) page boundary */
 #define PAGE_ALIGN(addr) ALIGN(addr, PAGE_SIZE)
 
@@ -2137,44 +2125,6 @@ static inline int arch_make_folio_accessible(struct folio *folio)
  */
 #include <linux/vmstat.h>
 
-static __always_inline void *lowmem_page_address(const struct page *page)
-{
-	return page_to_virt(page);
-}
-
-#if defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL)
-#define HASHED_PAGE_VIRTUAL
-#endif
-
-#if defined(WANT_PAGE_VIRTUAL)
-static inline void *page_address(const struct page *page)
-{
-	return page->virtual;
-}
-static inline void set_page_address(struct page *page, void *address)
-{
-	page->virtual = address;
-}
-#define page_address_init()  do { } while(0)
-#endif
-
-#if defined(HASHED_PAGE_VIRTUAL)
-void *page_address(const struct page *page);
-void set_page_address(struct page *page, void *virtual);
-void page_address_init(void);
-#endif
-
-#if !defined(HASHED_PAGE_VIRTUAL) && !defined(WANT_PAGE_VIRTUAL)
-#define page_address(page) lowmem_page_address(page)
-#define set_page_address(page, address)  do { } while(0)
-#define page_address_init()  do { } while(0)
-#endif
-
-static inline void *folio_address(const struct folio *folio)
-{
-	return page_address(&folio->page);
-}
-
 extern pgoff_t __page_file_index(struct page *page);
 
 /*
@@ -2237,10 +2187,6 @@ static inline void clear_page_pfmemalloc(struct page *page)
  */
 extern void pagefault_out_of_memory(void);
 
-#define offset_in_page(p)	((unsigned long)(p) & ~PAGE_MASK)
-#define offset_in_thp(page, p)	((unsigned long)(p) & (thp_size(page) - 1))
-#define offset_in_folio(folio, p) ((unsigned long)(p) & (folio_size(folio) - 1))
-
 /*
  * Parameter block passed down to zap_pte_range in exceptional cases.
  */
diff --git a/include/linux/mm/page_address.h b/include/linux/mm/page_address.h
new file mode 100644
index 000000000000..e1aaacc5003f
--- /dev/null
+++ b/include/linux/mm/page_address.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_MM_PAGE_ADDRESS_H
+#define _LINUX_MM_PAGE_ADDRESS_H
+
+#include <linux/mm_types.h> // for struct page
+#include <linux/mm/page_kasan_tag.h> // needed by the page_to_virt() macro on some architectures (e.g. arm64)
+#include <asm/page.h> // for PAGE_MASK, page_to_virt()
+
+#if defined(CONFIG_FLATMEM)
+#include <linux/mmzone.h> // for memmap (used by __pfn_to_page())
+#elif defined(CONFIG_SPARSEMEM_VMEMMAP)
+#include <asm/pgtable.h> // for vmemmap (used by __pfn_to_page())
+#elif defined(CONFIG_SPARSEMEM)
+#include <linux/mm/page_section.h> // for page_to_section() (used by __page_to_pfn())
+#endif
+
+#ifndef page_to_virt
+#define page_to_virt(x)	__va(PFN_PHYS(page_to_pfn(x)))
+#endif
+
+#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
+#define nth_page(page,n) pfn_to_page(page_to_pfn((page)) + (n))
+#define folio_page_idx(folio, p)	(page_to_pfn(p) - folio_pfn(folio))
+#else
+#define nth_page(page,n) ((page) + (n))
+#define folio_page_idx(folio, p)	((p) - &(folio)->page)
+#endif
+
+static __always_inline void *lowmem_page_address(const struct page *page)
+{
+	return page_to_virt(page);
+}
+
+#if defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL)
+#define HASHED_PAGE_VIRTUAL
+#endif
+
+#if defined(WANT_PAGE_VIRTUAL)
+static inline void *page_address(const struct page *page)
+{
+	return page->virtual;
+}
+static inline void set_page_address(struct page *page, void *address)
+{
+	page->virtual = address;
+}
+#define page_address_init()  do { } while(0)
+#endif
+
+#if defined(HASHED_PAGE_VIRTUAL)
+void *page_address(const struct page *page);
+void set_page_address(struct page *page, void *virtual);
+void page_address_init(void);
+#endif
+
+#if !defined(HASHED_PAGE_VIRTUAL) && !defined(WANT_PAGE_VIRTUAL)
+#define page_address(page) lowmem_page_address(page)
+#define set_page_address(page, address)  do { } while(0)
+#define page_address_init()  do { } while(0)
+#endif
+
+static inline void *folio_address(const struct folio *folio)
+{
+	return page_address(&folio->page);
+}
+
+#define offset_in_page(p)	((unsigned long)(p) & ~PAGE_MASK)
+#define offset_in_thp(page, p)	((unsigned long)(p) & (thp_size(page) - 1))
+#define offset_in_folio(folio, p) ((unsigned long)(p) & (folio_size(folio) - 1))
+
+#endif /* _LINUX_MM_PAGE_ADDRESS_H */
-- 
2.39.2