mm: split out a new pagewalk.h header from mm.h

Add a new header for the two handful of users of the walk_page_range /
walk_page_vma interface instead of polluting all users of mm.h with it.

Link: https://lore.kernel.org/r/20190828141955.22210-2-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

arch/openrisc/kernel/dma.c

@@ -16,6 +16,7 @@
  */
 
 #include <linux/dma-noncoherent.h>
+#include <linux/pagewalk.h>
 
 #include <asm/cpuinfo.h>
 #include <asm/spr_defs.h>

arch/powerpc/mm/book3s64/subpage_prot.c

@@ -7,7 +7,7 @@
 #include <linux/kernel.h>
 #include <linux/gfp.h>
 #include <linux/types.h>
-#include <linux/mm.h>
+#include <linux/pagewalk.h>
 #include <linux/hugetlb.h>
 #include <linux/syscalls.h>
 

arch/s390/mm/gmap.c

@@ -9,7 +9,7 @@
  */
 
 #include <linux/kernel.h>
-#include <linux/mm.h>
+#include <linux/pagewalk.h>
 #include <linux/swap.h>
 #include <linux/smp.h>
 #include <linux/spinlock.h>

fs/proc/task_mmu.c

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
-#include <linux/mm.h>
+#include <linux/pagewalk.h>
 #include <linux/vmacache.h>
 #include <linux/hugetlb.h>
 #include <linux/huge_mm.h>

include/linux/mm.h

@@ -1430,54 +1430,8 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long address,
 void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
 		unsigned long start, unsigned long end);
 
-/**
- * mm_walk - callbacks for walk_page_range
- * @pud_entry: if set, called for each non-empty PUD (2nd-level) entry
- *	       this handler should only handle pud_trans_huge() puds.
- *	       the pmd_entry or pte_entry callbacks will be used for
- *	       regular PUDs.
- * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
- *	       this handler is required to be able to handle
- *	       pmd_trans_huge() pmds.  They may simply choose to
- *	       split_huge_page() instead of handling it explicitly.
- * @pte_entry: if set, called for each non-empty PTE (4th-level) entry
- * @pte_hole: if set, called for each hole at all levels
- * @hugetlb_entry: if set, called for each hugetlb entry
- * @test_walk: caller specific callback function to determine whether
- *             we walk over the current vma or not. Returning 0
- *             value means "do page table walk over the current vma,"
- *             and a negative one means "abort current page table walk
- *             right now." 1 means "skip the current vma."
- * @mm:        mm_struct representing the target process of page table walk
- * @vma:       vma currently walked (NULL if walking outside vmas)
- * @private:   private data for callbacks' usage
- *
- * (see the comment on walk_page_range() for more details)
- */
-struct mm_walk {
-	int (*pud_entry)(pud_t *pud, unsigned long addr,
-			 unsigned long next, struct mm_walk *walk);
-	int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
-			 unsigned long next, struct mm_walk *walk);
-	int (*pte_entry)(pte_t *pte, unsigned long addr,
-			 unsigned long next, struct mm_walk *walk);
-	int (*pte_hole)(unsigned long addr, unsigned long next,
-			struct mm_walk *walk);
-	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
-			     unsigned long addr, unsigned long next,
-			     struct mm_walk *walk);
-	int (*test_walk)(unsigned long addr, unsigned long next,
-			struct mm_walk *walk);
-	struct mm_struct *mm;
-	struct vm_area_struct *vma;
-	void *private;
-};
-
 struct mmu_notifier_range;
 
-int walk_page_range(unsigned long addr, unsigned long end,
-		struct mm_walk *walk);
-int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk);
 void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
 		unsigned long end, unsigned long floor, unsigned long ceiling);
 int copy_page_range(struct mm_struct *dst, struct mm_struct *src,

include/linux/pagewalk.h

@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_PAGEWALK_H
+#define _LINUX_PAGEWALK_H
+
+#include <linux/mm.h>
+
+/**
+ * mm_walk - callbacks for walk_page_range
+ * @pud_entry: if set, called for each non-empty PUD (2nd-level) entry
+ *	       this handler should only handle pud_trans_huge() puds.
+ *	       the pmd_entry or pte_entry callbacks will be used for
+ *	       regular PUDs.
+ * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
+ *	       this handler is required to be able to handle
+ *	       pmd_trans_huge() pmds.  They may simply choose to
+ *	       split_huge_page() instead of handling it explicitly.
+ * @pte_entry: if set, called for each non-empty PTE (4th-level) entry
+ * @pte_hole: if set, called for each hole at all levels
+ * @hugetlb_entry: if set, called for each hugetlb entry
+ * @test_walk: caller specific callback function to determine whether
+ *             we walk over the current vma or not. Returning 0
+ *             value means "do page table walk over the current vma,"
+ *             and a negative one means "abort current page table walk
+ *             right now." 1 means "skip the current vma."
+ * @mm:        mm_struct representing the target process of page table walk
+ * @vma:       vma currently walked (NULL if walking outside vmas)
+ * @private:   private data for callbacks' usage
+ *
+ * (see the comment on walk_page_range() for more details)
+ */
+struct mm_walk {
+	int (*pud_entry)(pud_t *pud, unsigned long addr,
+			 unsigned long next, struct mm_walk *walk);
+	int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
+			 unsigned long next, struct mm_walk *walk);
+	int (*pte_entry)(pte_t *pte, unsigned long addr,
+			 unsigned long next, struct mm_walk *walk);
+	int (*pte_hole)(unsigned long addr, unsigned long next,
+			struct mm_walk *walk);
+	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
+			     unsigned long addr, unsigned long next,
+			     struct mm_walk *walk);
+	int (*test_walk)(unsigned long addr, unsigned long next,
+			struct mm_walk *walk);
+	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	void *private;
+};
+
+int walk_page_range(unsigned long addr, unsigned long end,
+		struct mm_walk *walk);
+int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk);
+
+#endif /* _LINUX_PAGEWALK_H */

mm/hmm.c

@@ -8,7 +8,7 @@
  * Refer to include/linux/hmm.h for information about heterogeneous memory
  * management or HMM for short.
  */
-#include <linux/mm.h>
+#include <linux/pagewalk.h>
 #include <linux/hmm.h>
 #include <linux/init.h>
 #include <linux/rmap.h>

mm/madvise.c

@@ -20,6 +20,7 @@
 #include <linux/file.h>
 #include <linux/blkdev.h>
 #include <linux/backing-dev.h>
+#include <linux/pagewalk.h>
 #include <linux/swap.h>
 #include <linux/swapops.h>
 #include <linux/shmem_fs.h>

mm/memcontrol.c

@@ -25,7 +25,7 @@
 #include <linux/page_counter.h>
 #include <linux/memcontrol.h>
 #include <linux/cgroup.h>
-#include <linux/mm.h>
+#include <linux/pagewalk.h>
 #include <linux/sched/mm.h>
 #include <linux/shmem_fs.h>
 #include <linux/hugetlb.h>

mm/mempolicy.c

@@ -68,7 +68,7 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/mempolicy.h>
-#include <linux/mm.h>
+#include <linux/pagewalk.h>
 #include <linux/highmem.h>
 #include <linux/hugetlb.h>
 #include <linux/kernel.h>

mm/migrate.c

@@ -38,6 +38,7 @@
 #include <linux/hugetlb.h>
 #include <linux/hugetlb_cgroup.h>
 #include <linux/gfp.h>
+#include <linux/pagewalk.h>
 #include <linux/pfn_t.h>
 #include <linux/memremap.h>
 #include <linux/userfaultfd_k.h>

mm/mincore.c

@@ -10,7 +10,7 @@
  */
 #include <linux/pagemap.h>
 #include <linux/gfp.h>
-#include <linux/mm.h>
+#include <linux/pagewalk.h>
 #include <linux/mman.h>
 #include <linux/syscalls.h>
 #include <linux/swap.h>

mm/mprotect.c

@@ -9,7 +9,7 @@
  *  (C) Copyright 2002 Red Hat Inc, All Rights Reserved
  */
 
-#include <linux/mm.h>
+#include <linux/pagewalk.h>
 #include <linux/hugetlb.h>
 #include <linux/shm.h>
 #include <linux/mman.h>

mm/pagewalk.c

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
-#include <linux/mm.h>
+#include <linux/pagewalk.h>
 #include <linux/highmem.h>
 #include <linux/sched.h>
 #include <linux/hugetlb.h>