cleanup the walk_page_range interface

cleanup the walk_page_range interface

[Christoph Hellwig]

Hi all,

this series is based on a patch from Linus to split the callbacks
passed to walk_page_range and walk_page_vma into a separate structure
that can be marked const, with various cleanups from me on top.

Note that both Thomas and Steven have series touching this area pending,
and there are a couple consumer in flux too - the hmm tree already
conflicts with this series, and I have potential dma changes on top of
the consumers in Thomas and Steven's series, so we'll probably need a
git tree similar to the hmm one to synchronize these updates.


This series is also available as a git tre here:

    git://git.infradead.org/users/hch/misc.git pagewalk-cleanup

Gitweb:

    http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/pagewalk-cleanup


Diffstat:

    14 files changed, 285 insertions(+), 278 deletions(-)

[PATCH 1/3] mm: split out a new pagewalk.h header from mm.h

[Christoph Hellwig]

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.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/openrisc/kernel/dma.c              |  1 +
 arch/powerpc/mm/book3s64/subpage_prot.c |  2 +-
 arch/s390/mm/gmap.c                     |  2 +-
 fs/proc/task_mmu.c                      |  2 +-
 include/linux/mm.h                      | 46 ---------------------
 include/linux/pagewalk.h                | 54 +++++++++++++++++++++++++
 mm/hmm.c                                |  2 +-
 mm/madvise.c                            |  1 +
 mm/memcontrol.c                         |  2 +-
 mm/mempolicy.c                          |  2 +-
 mm/migrate.c                            |  1 +
 mm/mincore.c                            |  2 +-
 mm/mprotect.c                           |  2 +-
 mm/pagewalk.c                           |  2 +-
 14 files changed, 66 insertions(+), 55 deletions(-)
 create mode 100644 include/linux/pagewalk.h

diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
index b41a79fcdbd9..c7812e6effa2 100644
--- a/arch/openrisc/kernel/dma.c
+++ b/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>
diff --git a/arch/powerpc/mm/book3s64/subpage_prot.c b/arch/powerpc/mm/book3s64/subpage_prot.c
index 9ba07e55c489..236f0a861ecc 100644
--- a/arch/powerpc/mm/book3s64/subpage_prot.c
+++ b/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>
 
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 39c3a6e3d262..cf80feae970d 100644
--- a/arch/s390/mm/gmap.c
+++ b/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>
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 731642e0f5a0..8857da830b86 100644
--- a/fs/proc/task_mmu.c
+++ b/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>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0334ca97c584..7cf955feb823 100644
--- a/include/linux/mm.h
+++ b/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,
diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h
new file mode 100644
index 000000000000..df278a94086d
--- /dev/null
+++ b/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 */
diff --git a/mm/hmm.c b/mm/hmm.c
index 16b6731a34db..909b846c11d4 100644
--- a/mm/hmm.c
+++ b/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>
diff --git a/mm/madvise.c b/mm/madvise.c
index 968df3aa069f..80a78bb16782 100644
--- a/mm/madvise.c
+++ b/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>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index cdbb7a84cb6e..ee01175e56d4 100644
--- a/mm/memcontrol.c
+++ b/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>
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index f48693f75b37..1ee6b6f49431 100644
--- a/mm/mempolicy.c
+++ b/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>
diff --git a/mm/migrate.c b/mm/migrate.c
index a42858d8e00b..019c426c6ef7 100644
--- a/mm/migrate.c
+++ b/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>
diff --git a/mm/mincore.c b/mm/mincore.c
index 4fe91d497436..3b051b6ab3fe 100644
--- a/mm/mincore.c
+++ b/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>
diff --git a/mm/mprotect.c b/mm/mprotect.c
index bf38dfbbb4b4..cc73318dbc25 100644
--- a/mm/mprotect.c
+++ b/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>
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index c3084ff2569d..8a92a961a2ee 100644
--- a/mm/pagewalk.c
+++ b/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>
-- 
2.20.1

[PATCH 2/3] pagewalk: seperate function pointers from iterator data

[Christoph Hellwig]

The mm_walk structure currently mixed data and code.  Split out the
operations vectors into a new mm_walk_ops structure, and while we
are changing the API also declare the mm_walk structure inside the
walk_page_range and walk_page_vma functions.

Based on patch from Linus Torvalds.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/openrisc/kernel/dma.c              |  22 +++--
 arch/powerpc/mm/book3s64/subpage_prot.c |  10 +-
 arch/s390/mm/gmap.c                     |  33 +++----
 fs/proc/task_mmu.c                      |  74 +++++++--------
 include/linux/pagewalk.h                |  64 +++++++------
 mm/hmm.c                                |  40 +++-----
 mm/madvise.c                            |  41 +++-----
 mm/memcontrol.c                         |  23 +++--
 mm/mempolicy.c                          |  15 ++-
 mm/migrate.c                            |  15 ++-
 mm/mincore.c                            |  15 ++-
 mm/mprotect.c                           |  24 ++---
 mm/pagewalk.c                           | 118 ++++++++++++++----------
 13 files changed, 245 insertions(+), 249 deletions(-)

diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
index c7812e6effa2..4d5b8bd1d795 100644
--- a/arch/openrisc/kernel/dma.c
+++ b/arch/openrisc/kernel/dma.c
@@ -44,6 +44,10 @@ page_set_nocache(pte_t *pte, unsigned long addr,
 	return 0;
 }
 
+static const struct mm_walk_ops set_nocache_walk_ops = {
+	.pte_entry		= page_set_nocache,
+};
+
 static int
 page_clear_nocache(pte_t *pte, unsigned long addr,
 		   unsigned long next, struct mm_walk *walk)
@@ -59,6 +63,10 @@ page_clear_nocache(pte_t *pte, unsigned long addr,
 	return 0;
 }
 
+static const struct mm_walk_ops clear_nocache_walk_ops = {
+	.pte_entry		= page_clear_nocache,
+};
+
 /*
  * Alloc "coherent" memory, which for OpenRISC means simply uncached.
  *
@@ -81,10 +89,6 @@ arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 {
 	unsigned long va;
 	void *page;
-	struct mm_walk walk = {
-		.pte_entry = page_set_nocache,
-		.mm = &init_mm
-	};
 
 	page = alloc_pages_exact(size, gfp | __GFP_ZERO);
 	if (!page)
@@ -99,7 +103,8 @@ arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 	 * We need to iterate through the pages, clearing the dcache for
 	 * them and setting the cache-inhibit bit.
 	 */
-	if (walk_page_range(va, va + size, &walk)) {
+	if (walk_page_range(&init_mm, va, va + size, &set_nocache_walk_ops,
+			NULL)) {
 		free_pages_exact(page, size);
 		return NULL;
 	}
@@ -112,13 +117,10 @@ arch_dma_free(struct device *dev, size_t size, void *vaddr,
 		dma_addr_t dma_handle, unsigned long attrs)
 {
 	unsigned long va = (unsigned long)vaddr;
-	struct mm_walk walk = {
-		.pte_entry = page_clear_nocache,
-		.mm = &init_mm
-	};
 
 	/* walk_page_range shouldn't be able to fail here */
-	WARN_ON(walk_page_range(va, va + size, &walk));
+	WARN_ON(walk_page_range(&init_mm, va, va + size,
+			&clear_nocache_walk_ops, NULL));
 
 	free_pages_exact(vaddr, size);
 }
diff --git a/arch/powerpc/mm/book3s64/subpage_prot.c b/arch/powerpc/mm/book3s64/subpage_prot.c
index 236f0a861ecc..2ef24a53f4c9 100644
--- a/arch/powerpc/mm/book3s64/subpage_prot.c
+++ b/arch/powerpc/mm/book3s64/subpage_prot.c
@@ -139,14 +139,14 @@ static int subpage_walk_pmd_entry(pmd_t *pmd, unsigned long addr,
 	return 0;
 }
 
+static const struct mm_walk_ops subpage_walk_ops = {
+	.pmd_entry	= subpage_walk_pmd_entry,
+};
+
 static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,
 				    unsigned long len)
 {
 	struct vm_area_struct *vma;
-	struct mm_walk subpage_proto_walk = {
-		.mm = mm,
-		.pmd_entry = subpage_walk_pmd_entry,
-	};
 
 	/*
 	 * We don't try too hard, we just mark all the vma in that range
@@ -163,7 +163,7 @@ static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,
 		if (vma->vm_start >= (addr + len))
 			break;
 		vma->vm_flags |= VM_NOHUGEPAGE;
-		walk_page_vma(vma, &subpage_proto_walk);
+		walk_page_vma(vma, &subpage_walk_ops, NULL);
 		vma = vma->vm_next;
 	}
 }
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index cf80feae970d..bd78d504fdad 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2521,13 +2521,9 @@ static int __zap_zero_pages(pmd_t *pmd, unsigned long start,
 	return 0;
 }
 
-static inline void zap_zero_pages(struct mm_struct *mm)
-{
-	struct mm_walk walk = { .pmd_entry = __zap_zero_pages };
-
-	walk.mm = mm;
-	walk_page_range(0, TASK_SIZE, &walk);
-}
+static const struct mm_walk_ops zap_zero_walk_ops = {
+	.pmd_entry	= __zap_zero_pages,
+};
 
 /*
  * switch on pgstes for its userspace process (for kvm)
@@ -2546,7 +2542,7 @@ int s390_enable_sie(void)
 	mm->context.has_pgste = 1;
 	/* split thp mappings and disable thp for future mappings */
 	thp_split_mm(mm);
-	zap_zero_pages(mm);
+	walk_page_range(mm, 0, TASK_SIZE, &zap_zero_walk_ops, NULL);
 	up_write(&mm->mmap_sem);
 	return 0;
 }
@@ -2589,12 +2585,13 @@ static int __s390_enable_skey_hugetlb(pte_t *pte, unsigned long addr,
 	return 0;
 }
 
+static const struct mm_walk_ops enable_skey_walk_ops = {
+	.hugetlb_entry		= __s390_enable_skey_hugetlb,
+	.pte_entry		= __s390_enable_skey_pte,
+};
+
 int s390_enable_skey(void)
 {
-	struct mm_walk walk = {
-		.hugetlb_entry = __s390_enable_skey_hugetlb,
-		.pte_entry = __s390_enable_skey_pte,
-	};
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	int rc = 0;
@@ -2614,8 +2611,7 @@ int s390_enable_skey(void)
 	}
 	mm->def_flags &= ~VM_MERGEABLE;
 
-	walk.mm = mm;
-	walk_page_range(0, TASK_SIZE, &walk);
+	walk_page_range(mm, 0, TASK_SIZE, &enable_skey_walk_ops, NULL);
 
 out_up:
 	up_write(&mm->mmap_sem);
@@ -2633,13 +2629,14 @@ static int __s390_reset_cmma(pte_t *pte, unsigned long addr,
 	return 0;
 }
 
+static const struct mm_walk_ops reset_cmma_walk_ops = {
+	.pte_entry		= __s390_reset_cmma,
+};
+
 void s390_reset_cmma(struct mm_struct *mm)
 {
-	struct mm_walk walk = { .pte_entry = __s390_reset_cmma };
-
 	down_write(&mm->mmap_sem);
-	walk.mm = mm;
-	walk_page_range(0, TASK_SIZE, &walk);
+	walk_page_range(mm, 0, TASK_SIZE, &reset_cmma_walk_ops, NULL);
 	up_write(&mm->mmap_sem);
 }
 EXPORT_SYMBOL_GPL(s390_reset_cmma);
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 8857da830b86..bdf65d5ba38b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -729,21 +729,24 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask,
 	}
 	return 0;
 }
+#else
+#define smaps_hugetlb_range	NULL
 #endif /* HUGETLB_PAGE */
 
+static const struct mm_walk_ops smaps_walk_ops = {
+	.pmd_entry		= smaps_pte_range,
+	.hugetlb_entry		= smaps_hugetlb_range,
+};
+
+static const struct mm_walk_ops smaps_shmem_walk_ops = {
+	.pmd_entry		= smaps_pte_range,
+	.hugetlb_entry		= smaps_hugetlb_range,
+	.pte_hole		= smaps_pte_hole,
+};
+
 static void smap_gather_stats(struct vm_area_struct *vma,
 			     struct mem_size_stats *mss)
 {
-	struct mm_walk smaps_walk = {
-		.pmd_entry = smaps_pte_range,
-#ifdef CONFIG_HUGETLB_PAGE
-		.hugetlb_entry = smaps_hugetlb_range,
-#endif
-		.mm = vma->vm_mm,
-	};
-
-	smaps_walk.private = mss;
-
 #ifdef CONFIG_SHMEM
 	/* In case of smaps_rollup, reset the value from previous vma */
 	mss->check_shmem_swap = false;
@@ -765,12 +768,13 @@ static void smap_gather_stats(struct vm_area_struct *vma,
 			mss->swap += shmem_swapped;
 		} else {
 			mss->check_shmem_swap = true;
-			smaps_walk.pte_hole = smaps_pte_hole;
+			walk_page_vma(vma, &smaps_shmem_walk_ops, mss);
+			return;
 		}
 	}
 #endif
 	/* mmap_sem is held in m_start */
-	walk_page_vma(vma, &smaps_walk);
+	walk_page_vma(vma, &smaps_walk_ops, mss);
 }
 
 #define SEQ_PUT_DEC(str, val) \
@@ -1118,6 +1122,11 @@ static int clear_refs_test_walk(unsigned long start, unsigned long end,
 	return 0;
 }
 
+static const struct mm_walk_ops clear_refs_walk_ops = {
+	.pmd_entry		= clear_refs_pte_range,
+	.test_walk		= clear_refs_test_walk,
+};
+
 static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 				size_t count, loff_t *ppos)
 {
@@ -1151,12 +1160,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 		struct clear_refs_private cp = {
 			.type = type,
 		};
-		struct mm_walk clear_refs_walk = {
-			.pmd_entry = clear_refs_pte_range,
-			.test_walk = clear_refs_test_walk,
-			.mm = mm,
-			.private = &cp,
-		};
 
 		if (type == CLEAR_REFS_MM_HIWATER_RSS) {
 			if (down_write_killable(&mm->mmap_sem)) {
@@ -1217,7 +1220,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 						0, NULL, mm, 0, -1UL);
 			mmu_notifier_invalidate_range_start(&range);
 		}
-		walk_page_range(0, mm->highest_vm_end, &clear_refs_walk);
+		walk_page_range(mm, 0, mm->highest_vm_end, &clear_refs_walk_ops,
+				&cp);
 		if (type == CLEAR_REFS_SOFT_DIRTY)
 			mmu_notifier_invalidate_range_end(&range);
 		tlb_finish_mmu(&tlb, 0, -1);
@@ -1489,8 +1493,16 @@ static int pagemap_hugetlb_range(pte_t *ptep, unsigned long hmask,
 
 	return err;
 }
+#else
+#define pagemap_hugetlb_range	NULL
 #endif /* HUGETLB_PAGE */
 
+static const struct mm_walk_ops pagemap_ops = {
+	.pmd_entry	= pagemap_pmd_range,
+	.pte_hole	= pagemap_pte_hole,
+	.hugetlb_entry	= pagemap_hugetlb_range,
+};
+
 /*
  * /proc/pid/pagemap - an array mapping virtual pages to pfns
  *
@@ -1522,7 +1534,6 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
 {
 	struct mm_struct *mm = file->private_data;
 	struct pagemapread pm;
-	struct mm_walk pagemap_walk = {};
 	unsigned long src;
 	unsigned long svpfn;
 	unsigned long start_vaddr;
@@ -1550,14 +1561,6 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
 	if (!pm.buffer)
 		goto out_mm;
 
-	pagemap_walk.pmd_entry = pagemap_pmd_range;
-	pagemap_walk.pte_hole = pagemap_pte_hole;
-#ifdef CONFIG_HUGETLB_PAGE
-	pagemap_walk.hugetlb_entry = pagemap_hugetlb_range;
-#endif
-	pagemap_walk.mm = mm;
-	pagemap_walk.private = &pm;
-
 	src = *ppos;
 	svpfn = src / PM_ENTRY_BYTES;
 	start_vaddr = svpfn << PAGE_SHIFT;
@@ -1586,7 +1589,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
 		ret = down_read_killable(&mm->mmap_sem);
 		if (ret)
 			goto out_free;
-		ret = walk_page_range(start_vaddr, end, &pagemap_walk);
+		ret = walk_page_range(mm, start_vaddr, end, &pagemap_ops, &pm);
 		up_read(&mm->mmap_sem);
 		start_vaddr = end;
 
@@ -1798,6 +1801,11 @@ static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
 }
 #endif
 
+static const struct mm_walk_ops show_numa_ops = {
+	.hugetlb_entry = gather_hugetlb_stats,
+	.pmd_entry = gather_pte_stats,
+};
+
 /*
  * Display pages allocated per node and memory policy via /proc.
  */
@@ -1809,12 +1817,6 @@ static int show_numa_map(struct seq_file *m, void *v)
 	struct numa_maps *md = &numa_priv->md;
 	struct file *file = vma->vm_file;
 	struct mm_struct *mm = vma->vm_mm;
-	struct mm_walk walk = {
-		.hugetlb_entry = gather_hugetlb_stats,
-		.pmd_entry = gather_pte_stats,
-		.private = md,
-		.mm = mm,
-	};
 	struct mempolicy *pol;
 	char buffer[64];
 	int nid;
@@ -1848,7 +1850,7 @@ static int show_numa_map(struct seq_file *m, void *v)
 		seq_puts(m, " huge");
 
 	/* mmap_sem is held by m_start */
-	walk_page_vma(vma, &walk);
+	walk_page_vma(vma, &show_numa_ops, md);
 
 	if (!md->pages)
 		goto out;
diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h
index df278a94086d..bddd9759bab9 100644
--- a/include/linux/pagewalk.h
+++ b/include/linux/pagewalk.h
@@ -4,31 +4,28 @@
 
 #include <linux/mm.h>
 
+struct mm_walk;
+
 /**
- * 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)
+ * mm_walk_ops - 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 means
+ *			"do page table walk over the current vma", returning
+ *			a negative value means "abort current page table walk
+ *			right now" and returning 1 means "skip the current vma"
  */
-struct mm_walk {
+struct mm_walk_ops {
 	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,
@@ -42,13 +39,28 @@ struct mm_walk {
 			     struct mm_walk *walk);
 	int (*test_walk)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
+};
+
+/**
+ * mm_walk - walk_page_range data
+ * @ops:	operation to call during the walk
+ * @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 {
+	const struct mm_walk_ops *ops;
 	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);
+int walk_page_range(struct mm_struct *mm, unsigned long start,
+		unsigned long end, const struct mm_walk_ops *ops,
+		void *private);
+int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
+		void *private);
 
 #endif /* _LINUX_PAGEWALK_H */
diff --git a/mm/hmm.c b/mm/hmm.c
index 909b846c11d4..37933f886dbe 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -941,6 +941,13 @@ void hmm_range_unregister(struct hmm_range *range)
 }
 EXPORT_SYMBOL(hmm_range_unregister);
 
+static const struct mm_walk_ops hmm_walk_ops = {
+	.pud_entry	= hmm_vma_walk_pud,
+	.pmd_entry	= hmm_vma_walk_pmd,
+	.pte_hole	= hmm_vma_walk_hole,
+	.hugetlb_entry	= hmm_vma_walk_hugetlb_entry,
+};
+
 /*
  * hmm_range_snapshot() - snapshot CPU page table for a range
  * @range: range
@@ -961,7 +968,6 @@ long hmm_range_snapshot(struct hmm_range *range)
 	struct hmm_vma_walk hmm_vma_walk;
 	struct hmm *hmm = range->hmm;
 	struct vm_area_struct *vma;
-	struct mm_walk mm_walk;
 
 	lockdep_assert_held(&hmm->mm->mmap_sem);
 	do {
@@ -999,20 +1005,10 @@ long hmm_range_snapshot(struct hmm_range *range)
 		hmm_vma_walk.last = start;
 		hmm_vma_walk.fault = false;
 		hmm_vma_walk.range = range;
-		mm_walk.private = &hmm_vma_walk;
-		end = min(range->end, vma->vm_end);
 
-		mm_walk.vma = vma;
-		mm_walk.mm = vma->vm_mm;
-		mm_walk.pte_entry = NULL;
-		mm_walk.test_walk = NULL;
-		mm_walk.hugetlb_entry = NULL;
-		mm_walk.pud_entry = hmm_vma_walk_pud;
-		mm_walk.pmd_entry = hmm_vma_walk_pmd;
-		mm_walk.pte_hole = hmm_vma_walk_hole;
-		mm_walk.hugetlb_entry = hmm_vma_walk_hugetlb_entry;
-
-		walk_page_range(start, end, &mm_walk);
+		end = min(range->end, vma->vm_end);
+		walk_page_range(vma->vm_mm, start, end, &hmm_walk_ops,
+				&hmm_vma_walk);
 		start = end;
 	} while (start < range->end);
 
@@ -1055,7 +1051,6 @@ long hmm_range_fault(struct hmm_range *range, bool block)
 	struct hmm_vma_walk hmm_vma_walk;
 	struct hmm *hmm = range->hmm;
 	struct vm_area_struct *vma;
-	struct mm_walk mm_walk;
 	int ret;
 
 	lockdep_assert_held(&hmm->mm->mmap_sem);
@@ -1096,21 +1091,14 @@ long hmm_range_fault(struct hmm_range *range, bool block)
 		hmm_vma_walk.fault = true;
 		hmm_vma_walk.block = block;
 		hmm_vma_walk.range = range;
-		mm_walk.private = &hmm_vma_walk;
 		end = min(range->end, vma->vm_end);
 
-		mm_walk.vma = vma;
-		mm_walk.mm = vma->vm_mm;
-		mm_walk.pte_entry = NULL;
-		mm_walk.test_walk = NULL;
-		mm_walk.hugetlb_entry = NULL;
-		mm_walk.pud_entry = hmm_vma_walk_pud;
-		mm_walk.pmd_entry = hmm_vma_walk_pmd;
-		mm_walk.pte_hole = hmm_vma_walk_hole;
-		mm_walk.hugetlb_entry = hmm_vma_walk_hugetlb_entry;
+		walk_page_range(vma->vm_mm, start, end, &hmm_walk_ops,
+				&hmm_vma_walk);
 
 		do {
-			ret = walk_page_range(start, end, &mm_walk);
+			ret = walk_page_range(vma->vm_mm, start, end,
+					&hmm_walk_ops, &hmm_vma_walk);
 			start = hmm_vma_walk.last;
 
 			/* Keep trying while the range is valid. */
diff --git a/mm/madvise.c b/mm/madvise.c
index 80a78bb16782..afe2b015ea58 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -226,19 +226,9 @@ static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
 	return 0;
 }
 
-static void force_swapin_readahead(struct vm_area_struct *vma,
-		unsigned long start, unsigned long end)
-{
-	struct mm_walk walk = {
-		.mm = vma->vm_mm,
-		.pmd_entry = swapin_walk_pmd_entry,
-		.private = vma,
-	};
-
-	walk_page_range(start, end, &walk);
-
-	lru_add_drain();	/* Push any new pages onto the LRU now */
-}
+static const struct mm_walk_ops swapin_walk_ops = {
+	.pmd_entry		= swapin_walk_pmd_entry,
+};
 
 static void force_shm_swapin_readahead(struct vm_area_struct *vma,
 		unsigned long start, unsigned long end,
@@ -280,7 +270,8 @@ static long madvise_willneed(struct vm_area_struct *vma,
 	*prev = vma;
 #ifdef CONFIG_SWAP
 	if (!file) {
-		force_swapin_readahead(vma, start, end);
+		walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
+		lru_add_drain(); /* Push any new pages onto the LRU now */
 		return 0;
 	}
 
@@ -441,20 +432,9 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 	return 0;
 }
 
-static void madvise_free_page_range(struct mmu_gather *tlb,
-			     struct vm_area_struct *vma,
-			     unsigned long addr, unsigned long end)
-{
-	struct mm_walk free_walk = {
-		.pmd_entry = madvise_free_pte_range,
-		.mm = vma->vm_mm,
-		.private = tlb,
-	};
-
-	tlb_start_vma(tlb, vma);
-	walk_page_range(addr, end, &free_walk);
-	tlb_end_vma(tlb, vma);
-}
+static const struct mm_walk_ops madvise_free_walk_ops = {
+	.pmd_entry		= madvise_free_pte_range,
+};
 
 static int madvise_free_single_vma(struct vm_area_struct *vma,
 			unsigned long start_addr, unsigned long end_addr)
@@ -481,7 +461,10 @@ static int madvise_free_single_vma(struct vm_area_struct *vma,
 	update_hiwater_rss(mm);
 
 	mmu_notifier_invalidate_range_start(&range);
-	madvise_free_page_range(&tlb, vma, range.start, range.end);
+	tlb_start_vma(&tlb, vma);
+	walk_page_range(vma->vm_mm, range.start, range.end,
+			&madvise_free_walk_ops, &tlb);
+	tlb_end_vma(&tlb, vma);
 	mmu_notifier_invalidate_range_end(&range);
 	tlb_finish_mmu(&tlb, range.start, range.end);
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ee01175e56d4..5d159f9391ff 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5244,17 +5244,16 @@ static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
 	return 0;
 }
 
+static const struct mm_walk_ops precharge_walk_ops = {
+	.pmd_entry	= mem_cgroup_count_precharge_pte_range,
+};
+
 static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
 {
 	unsigned long precharge;
 
-	struct mm_walk mem_cgroup_count_precharge_walk = {
-		.pmd_entry = mem_cgroup_count_precharge_pte_range,
-		.mm = mm,
-	};
 	down_read(&mm->mmap_sem);
-	walk_page_range(0, mm->highest_vm_end,
-			&mem_cgroup_count_precharge_walk);
+	walk_page_range(mm, 0, mm->highest_vm_end, &precharge_walk_ops, NULL);
 	up_read(&mm->mmap_sem);
 
 	precharge = mc.precharge;
@@ -5523,13 +5522,12 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
 	return ret;
 }
 
+static const struct mm_walk_ops charge_walk_ops = {
+	.pmd_entry	= mem_cgroup_move_charge_pte_range,
+};
+
 static void mem_cgroup_move_charge(void)
 {
-	struct mm_walk mem_cgroup_move_charge_walk = {
-		.pmd_entry = mem_cgroup_move_charge_pte_range,
-		.mm = mc.mm,
-	};
-
 	lru_add_drain_all();
 	/*
 	 * Signal lock_page_memcg() to take the memcg's move_lock
@@ -5555,7 +5553,8 @@ static void mem_cgroup_move_charge(void)
 	 * When we have consumed all precharges and failed in doing
 	 * additional charge, the page walk just aborts.
 	 */
-	walk_page_range(0, mc.mm->highest_vm_end, &mem_cgroup_move_charge_walk);
+	walk_page_range(mc.mm, 0, mc.mm->highest_vm_end, &charge_walk_ops,
+			NULL);
 
 	up_read(&mc.mm->mmap_sem);
 	atomic_dec(&mc.from->moving_account);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 1ee6b6f49431..6712bceae213 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -634,6 +634,12 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
 	return 1;
 }
 
+static const struct mm_walk_ops queue_pages_walk_ops = {
+	.hugetlb_entry		= queue_pages_hugetlb,
+	.pmd_entry		= queue_pages_pte_range,
+	.test_walk		= queue_pages_test_walk,
+};
+
 /*
  * Walk through page tables and collect pages to be migrated.
  *
@@ -652,15 +658,8 @@ queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
 		.nmask = nodes,
 		.prev = NULL,
 	};
-	struct mm_walk queue_pages_walk = {
-		.hugetlb_entry = queue_pages_hugetlb,
-		.pmd_entry = queue_pages_pte_range,
-		.test_walk = queue_pages_test_walk,
-		.mm = mm,
-		.private = &qp,
-	};
 
-	return walk_page_range(start, end, &queue_pages_walk);
+	return walk_page_range(mm, start, end, &queue_pages_walk_ops, &qp);
 }
 
 /*
diff --git a/mm/migrate.c b/mm/migrate.c
index 019c426c6ef7..75de4378dfcd 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2330,6 +2330,11 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 	return 0;
 }
 
+static const struct mm_walk_ops migrate_vma_walk_ops = {
+	.pmd_entry		= migrate_vma_collect_pmd,
+	.pte_hole		= migrate_vma_collect_hole,
+};
+
 /*
  * migrate_vma_collect() - collect pages over a range of virtual addresses
  * @migrate: migrate struct containing all migration information
@@ -2341,19 +2346,13 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 static void migrate_vma_collect(struct migrate_vma *migrate)
 {
 	struct mmu_notifier_range range;
-	struct mm_walk mm_walk = {
-		.pmd_entry = migrate_vma_collect_pmd,
-		.pte_hole = migrate_vma_collect_hole,
-		.vma = migrate->vma,
-		.mm = migrate->vma->vm_mm,
-		.private = migrate,
-	};
 
 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm_walk.mm,
 				migrate->start,
 				migrate->end);
 	mmu_notifier_invalidate_range_start(&range);
-	walk_page_range(migrate->start, migrate->end, &mm_walk);
+	walk_page_range(migrate->vma->vm_mm, migrate->start, migrate->end,
+			&migrate_vma_walk_ops, migrate);
 	mmu_notifier_invalidate_range_end(&range);
 
 	migrate->end = migrate->start + (migrate->npages << PAGE_SHIFT);
diff --git a/mm/mincore.c b/mm/mincore.c
index 3b051b6ab3fe..f9a9dbe8cd33 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -193,6 +193,12 @@ static inline bool can_do_mincore(struct vm_area_struct *vma)
 		inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
 }
 
+static const struct mm_walk_ops mincore_walk_ops = {
+	.pmd_entry		= mincore_pte_range,
+	.pte_hole		= mincore_unmapped_range,
+	.hugetlb_entry		= mincore_hugetlb,
+};
+
 /*
  * Do a chunk of "sys_mincore()". We've already checked
  * all the arguments, we hold the mmap semaphore: we should
@@ -203,12 +209,6 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v
 	struct vm_area_struct *vma;
 	unsigned long end;
 	int err;
-	struct mm_walk mincore_walk = {
-		.pmd_entry = mincore_pte_range,
-		.pte_hole = mincore_unmapped_range,
-		.hugetlb_entry = mincore_hugetlb,
-		.private = vec,
-	};
 
 	vma = find_vma(current->mm, addr);
 	if (!vma || addr < vma->vm_start)
@@ -219,8 +219,7 @@ static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *v
 		memset(vec, 1, pages);
 		return pages;
 	}
-	mincore_walk.mm = vma->vm_mm;
-	err = walk_page_range(addr, end, &mincore_walk);
+	err = walk_page_range(vma->vm_mm, addr, end, &mincore_walk_ops, vec);
 	if (err < 0)
 		return err;
 	return (end - addr) >> PAGE_SHIFT;
diff --git a/mm/mprotect.c b/mm/mprotect.c
index cc73318dbc25..675e5d34a507 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -329,20 +329,11 @@ static int prot_none_test(unsigned long addr, unsigned long next,
 	return 0;
 }
 
-static int prot_none_walk(struct vm_area_struct *vma, unsigned long start,
-			   unsigned long end, unsigned long newflags)
-{
-	pgprot_t new_pgprot = vm_get_page_prot(newflags);
-	struct mm_walk prot_none_walk = {
-		.pte_entry = prot_none_pte_entry,
-		.hugetlb_entry = prot_none_hugetlb_entry,
-		.test_walk = prot_none_test,
-		.mm = current->mm,
-		.private = &new_pgprot,
-	};
-
-	return walk_page_range(start, end, &prot_none_walk);
-}
+static const struct mm_walk_ops prot_none_walk_ops = {
+	.pte_entry		= prot_none_pte_entry,
+	.hugetlb_entry		= prot_none_hugetlb_entry,
+	.test_walk		= prot_none_test,
+};
 
 int
 mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
@@ -369,7 +360,10 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
 	if (arch_has_pfn_modify_check() &&
 	    (vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
 	    (newflags & (VM_READ|VM_WRITE|VM_EXEC)) == 0) {
-		error = prot_none_walk(vma, start, end, newflags);
+		pgprot_t new_pgprot = vm_get_page_prot(newflags);
+
+		error = walk_page_range(current->mm, start, end,
+				&prot_none_walk_ops, &new_pgprot);
 		if (error)
 			return error;
 	}
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 8a92a961a2ee..28510fc0dde1 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -9,10 +9,11 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 {
 	pte_t *pte;
 	int err = 0;
+	const struct mm_walk_ops *ops = walk->ops;
 
 	pte = pte_offset_map(pmd, addr);
 	for (;;) {
-		err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
+		err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
 		if (err)
 		       break;
 		addr += PAGE_SIZE;
@@ -30,6 +31,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 {
 	pmd_t *pmd;
 	unsigned long next;
+	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
 
 	pmd = pmd_offset(pud, addr);
@@ -37,8 +39,8 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 again:
 		next = pmd_addr_end(addr, end);
 		if (pmd_none(*pmd) || !walk->vma) {
-			if (walk->pte_hole)
-				err = walk->pte_hole(addr, next, walk);
+			if (ops->pte_hole)
+				err = ops->pte_hole(addr, next, walk);
 			if (err)
 				break;
 			continue;
@@ -47,8 +49,8 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 		 * This implies that each ->pmd_entry() handler
 		 * needs to know about pmd_trans_huge() pmds
 		 */
-		if (walk->pmd_entry)
-			err = walk->pmd_entry(pmd, addr, next, walk);
+		if (ops->pmd_entry)
+			err = ops->pmd_entry(pmd, addr, next, walk);
 		if (err)
 			break;
 
@@ -56,7 +58,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 		 * Check this here so we only break down trans_huge
 		 * pages when we _need_ to
 		 */
-		if (!walk->pte_entry)
+		if (!ops->pte_entry)
 			continue;
 
 		split_huge_pmd(walk->vma, pmd, addr);
@@ -75,6 +77,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 {
 	pud_t *pud;
 	unsigned long next;
+	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
 
 	pud = pud_offset(p4d, addr);
@@ -82,18 +85,18 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
  again:
 		next = pud_addr_end(addr, end);
 		if (pud_none(*pud) || !walk->vma) {
-			if (walk->pte_hole)
-				err = walk->pte_hole(addr, next, walk);
+			if (ops->pte_hole)
+				err = ops->pte_hole(addr, next, walk);
 			if (err)
 				break;
 			continue;
 		}
 
-		if (walk->pud_entry) {
+		if (ops->pud_entry) {
 			spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma);
 
 			if (ptl) {
-				err = walk->pud_entry(pud, addr, next, walk);
+				err = ops->pud_entry(pud, addr, next, walk);
 				spin_unlock(ptl);
 				if (err)
 					break;
@@ -105,7 +108,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
 		if (pud_none(*pud))
 			goto again;
 
-		if (walk->pmd_entry || walk->pte_entry)
+		if (ops->pmd_entry || ops->pte_entry)
 			err = walk_pmd_range(pud, addr, next, walk);
 		if (err)
 			break;
@@ -119,19 +122,20 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
 {
 	p4d_t *p4d;
 	unsigned long next;
+	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
 
 	p4d = p4d_offset(pgd, addr);
 	do {
 		next = p4d_addr_end(addr, end);
 		if (p4d_none_or_clear_bad(p4d)) {
-			if (walk->pte_hole)
-				err = walk->pte_hole(addr, next, walk);
+			if (ops->pte_hole)
+				err = ops->pte_hole(addr, next, walk);
 			if (err)
 				break;
 			continue;
 		}
-		if (walk->pmd_entry || walk->pte_entry)
+		if (ops->pmd_entry || ops->pte_entry)
 			err = walk_pud_range(p4d, addr, next, walk);
 		if (err)
 			break;
@@ -145,19 +149,20 @@ static int walk_pgd_range(unsigned long addr, unsigned long end,
 {
 	pgd_t *pgd;
 	unsigned long next;
+	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
 
 	pgd = pgd_offset(walk->mm, addr);
 	do {
 		next = pgd_addr_end(addr, end);
 		if (pgd_none_or_clear_bad(pgd)) {
-			if (walk->pte_hole)
-				err = walk->pte_hole(addr, next, walk);
+			if (ops->pte_hole)
+				err = ops->pte_hole(addr, next, walk);
 			if (err)
 				break;
 			continue;
 		}
-		if (walk->pmd_entry || walk->pte_entry)
+		if (ops->pmd_entry || ops->pte_entry)
 			err = walk_p4d_range(pgd, addr, next, walk);
 		if (err)
 			break;
@@ -183,6 +188,7 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 	unsigned long hmask = huge_page_mask(h);
 	unsigned long sz = huge_page_size(h);
 	pte_t *pte;
+	const struct mm_walk_ops *ops = walk->ops;
 	int err = 0;
 
 	do {
@@ -190,9 +196,9 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 		pte = huge_pte_offset(walk->mm, addr & hmask, sz);
 
 		if (pte)
-			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
-		else if (walk->pte_hole)
-			err = walk->pte_hole(addr, next, walk);
+			err = ops->hugetlb_entry(pte, hmask, addr, next, walk);
+		else if (ops->pte_hole)
+			err = ops->pte_hole(addr, next, walk);
 
 		if (err)
 			break;
@@ -220,9 +226,10 @@ static int walk_page_test(unsigned long start, unsigned long end,
 			struct mm_walk *walk)
 {
 	struct vm_area_struct *vma = walk->vma;
+	const struct mm_walk_ops *ops = walk->ops;
 
-	if (walk->test_walk)
-		return walk->test_walk(start, end, walk);
+	if (ops->test_walk)
+		return ops->test_walk(start, end, walk);
 
 	/*
 	 * vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP
@@ -234,8 +241,8 @@ static int walk_page_test(unsigned long start, unsigned long end,
 	 */
 	if (vma->vm_flags & VM_PFNMAP) {
 		int err = 1;
-		if (walk->pte_hole)
-			err = walk->pte_hole(start, end, walk);
+		if (ops->pte_hole)
+			err = ops->pte_hole(start, end, walk);
 		return err ? err : 1;
 	}
 	return 0;
@@ -248,7 +255,8 @@ static int __walk_page_range(unsigned long start, unsigned long end,
 	struct vm_area_struct *vma = walk->vma;
 
 	if (vma && is_vm_hugetlb_page(vma)) {
-		if (walk->hugetlb_entry)
+		const struct mm_walk_ops *ops = walk->ops;
+		if (ops->hugetlb_entry)
 			err = walk_hugetlb_range(start, end, walk);
 	} else
 		err = walk_pgd_range(start, end, walk);
@@ -258,11 +266,13 @@ static int __walk_page_range(unsigned long start, unsigned long end,
 
 /**
  * walk_page_range - walk page table with caller specific callbacks
- * @start: start address of the virtual address range
- * @end: end address of the virtual address range
- * @walk: mm_walk structure defining the callbacks and the target address space
+ * @mm:		mm_struct representing the target process of page table walk
+ * @start:	start address of the virtual address range
+ * @end:	end address of the virtual address range
+ * @ops:	operation to call during the walk
+ * @private:	private data for callbacks' usage
  *
- * Recursively walk the page table tree of the process represented by @walk->mm
+ * Recursively walk the page table tree of the process represented by @mm
  * within the virtual address range [@start, @end). During walking, we can do
  * some caller-specific works for each entry, by setting up pmd_entry(),
  * pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these
@@ -283,42 +293,48 @@ static int __walk_page_range(unsigned long start, unsigned long end,
  *
  * struct mm_walk keeps current values of some common data like vma and pmd,
  * which are useful for the access from callbacks. If you want to pass some
- * caller-specific data to callbacks, @walk->private should be helpful.
+ * caller-specific data to callbacks, @private should be helpful.
  *
  * Locking:
  *   Callers of walk_page_range() and walk_page_vma() should hold
  *   @walk->mm->mmap_sem, because these function traverse vma list and/or
  *   access to vma's data.
  */
-int walk_page_range(unsigned long start, unsigned long end,
-		    struct mm_walk *walk)
+int walk_page_range(struct mm_struct *mm, unsigned long start,
+		unsigned long end, const struct mm_walk_ops *ops,
+		void *private)
 {
 	int err = 0;
 	unsigned long next;
 	struct vm_area_struct *vma;
+	struct mm_walk walk = {
+		.ops		= ops,
+		.mm		= mm,
+		.private	= private,
+	};
 
 	if (start >= end)
 		return -EINVAL;
 
-	if (!walk->mm)
+	if (!walk.mm)
 		return -EINVAL;
 
-	VM_BUG_ON_MM(!rwsem_is_locked(&walk->mm->mmap_sem), walk->mm);
+	VM_BUG_ON_MM(!rwsem_is_locked(&walk.mm->mmap_sem), walk.mm);
 
-	vma = find_vma(walk->mm, start);
+	vma = find_vma(walk.mm, start);
 	do {
 		if (!vma) { /* after the last vma */
-			walk->vma = NULL;
+			walk.vma = NULL;
 			next = end;
 		} else if (start < vma->vm_start) { /* outside vma */
-			walk->vma = NULL;
+			walk.vma = NULL;
 			next = min(end, vma->vm_start);
 		} else { /* inside vma */
-			walk->vma = vma;
+			walk.vma = vma;
 			next = min(end, vma->vm_end);
 			vma = vma->vm_next;
 
-			err = walk_page_test(start, next, walk);
+			err = walk_page_test(start, next, &walk);
 			if (err > 0) {
 				/*
 				 * positive return values are purely for
@@ -331,28 +347,34 @@ int walk_page_range(unsigned long start, unsigned long end,
 			if (err < 0)
 				break;
 		}
-		if (walk->vma || walk->pte_hole)
-			err = __walk_page_range(start, next, walk);
+		if (walk.vma || walk.ops->pte_hole)
+			err = __walk_page_range(start, next, &walk);
 		if (err)
 			break;
 	} while (start = next, start < end);
 	return err;
 }
 
-int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk)
+int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
+		void *private)
 {
+	struct mm_walk walk = {
+		.ops		= ops,
+		.mm		= vma->vm_mm,
+		.vma		= vma,
+		.private	= private,
+	};
 	int err;
 
-	if (!walk->mm)
+	if (!walk.mm)
 		return -EINVAL;
 
-	VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
-	VM_BUG_ON(!vma);
-	walk->vma = vma;
-	err = walk_page_test(vma->vm_start, vma->vm_end, walk);
+	VM_BUG_ON(!rwsem_is_locked(&vma->vm_mm->mmap_sem));
+
+	err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
 	if (err > 0)
 		return 0;
 	if (err < 0)
 		return err;
-	return __walk_page_range(vma->vm_start, vma->vm_end, walk);
+	return __walk_page_range(vma->vm_start, vma->vm_end, &walk);
 }
-- 
2.20.1

[PATCH 3/3] pagewalk: use lockdep_assert_held for locking validation

[Christoph Hellwig]

Use lockdep to check for held locks instead of using home grown
asserts.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/pagewalk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 28510fc0dde1..9ec1885ceed7 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -319,7 +319,7 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
 	if (!walk.mm)
 		return -EINVAL;
 
-	VM_BUG_ON_MM(!rwsem_is_locked(&walk.mm->mmap_sem), walk.mm);
+	lockdep_assert_held(&walk.mm->mmap_sem);
 
 	vma = find_vma(walk.mm, start);
 	do {
@@ -369,7 +369,7 @@ int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
 	if (!walk.mm)
 		return -EINVAL;
 
-	VM_BUG_ON(!rwsem_is_locked(&vma->vm_mm->mmap_sem));
+	lockdep_assert_held(&walk.mm->mmap_sem);
 
 	err = walk_page_test(vma->vm_start, vma->vm_end, &walk);
 	if (err > 0)
-- 
2.20.1

Re: cleanup the walk_page_range interface

[Linus Torvalds]

On Thu, Aug 8, 2019 at 8:42 AM Christoph Hellwig <hch@lst.de> wrote:
>
> this series is based on a patch from Linus to split the callbacks
> passed to walk_page_range and walk_page_vma into a separate structure
> that can be marked const, with various cleanups from me on top.

The whole series looks good to me. Ack.

> Note that both Thomas and Steven have series touching this area pending,
> and there are a couple consumer in flux too - the hmm tree already
> conflicts with this series, and I have potential dma changes on top of
> the consumers in Thomas and Steven's series, so we'll probably need a
> git tree similar to the hmm one to synchronize these updates.

I'd be willing to just merge this now, if that helps. The conversion
is mechanical, and my only slight worry would be that at least for my
original patch I didn't build-test the (few) non-x86
architecture-specific cases. But I did end up looking at them fairly
closely  (basically using some grep/sed scripts to see that the
conversions I did matched the same patterns). And your changes look
like obvious improvements too where any mistake would have been caught
by the compiler.

So I'm not all that worried from a functionality standpoint, and if
this will help the next merge window, I'll happily pull now.

             Linus

Re: [PATCH 3/3] pagewalk: use lockdep_assert_held for locking validation

[Matthew Wilcox]

On Thu, Aug 08, 2019 at 06:42:40PM +0300, Christoph Hellwig wrote:
> Use lockdep to check for held locks instead of using home grown
> asserts.
> 
> @@ -319,7 +319,7 @@ int walk_page_range(struct mm_struct *mm, unsigned long start,
>  	if (!walk.mm)
>  		return -EINVAL;
>  
> -	VM_BUG_ON_MM(!rwsem_is_locked(&walk.mm->mmap_sem), walk.mm);
> +	lockdep_assert_held(&walk.mm->mmap_sem);

It occurs to me that this is exactly the pattern that lockdep_pin_lock()
was designed for.  I'm pretty sure things will go badly if any callee
unlocks then relocks the lock.

Re: [PATCH 2/3] pagewalk: seperate function pointers from iterator data

[Thomas Hellstrom]

On 8/8/19 5:42 PM, Christoph Hellwig wrote:
> The mm_walk structure currently mixed data and code.  Split out the
> operations vectors into a new mm_walk_ops structure, and while we
> are changing the API also declare the mm_walk structure inside the
> walk_page_range and walk_page_vma functions.
>
> Based on patch from Linus Torvalds.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Typo: For the patch title s/seperate/separate/

Otherwise for the series

Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>

/Thomas

Re: cleanup the walk_page_range interface

[Christoph Hellwig]

On Thu, Aug 08, 2019 at 10:50:37AM -0700, Linus Torvalds wrote:
> > Note that both Thomas and Steven have series touching this area pending,
> > and there are a couple consumer in flux too - the hmm tree already
> > conflicts with this series, and I have potential dma changes on top of
> > the consumers in Thomas and Steven's series, so we'll probably need a
> > git tree similar to the hmm one to synchronize these updates.
> 
> I'd be willing to just merge this now, if that helps. The conversion
> is mechanical, and my only slight worry would be that at least for my
> original patch I didn't build-test the (few) non-x86
> architecture-specific cases. But I did end up looking at them fairly
> closely  (basically using some grep/sed scripts to see that the
> conversions I did matched the same patterns). And your changes look
> like obvious improvements too where any mistake would have been caught
> by the compiler.

I did cross compile the s390 and powerpc bits, but I do not have an
openrisc compiler.

> So I'm not all that worried from a functionality standpoint, and if
> this will help the next merge window, I'll happily pull now.

That would help with this series vs the others, but not with the other
series vs each other.

Re: cleanup the walk_page_range interface

[Thomas Hellstrom]

On 8/8/19 11:56 PM, Christoph Hellwig wrote:
> On Thu, Aug 08, 2019 at 10:50:37AM -0700, Linus Torvalds wrote:
>>> Note that both Thomas and Steven have series touching this area pending,
>>> and there are a couple consumer in flux too - the hmm tree already
>>> conflicts with this series, and I have potential dma changes on top of
>>> the consumers in Thomas and Steven's series, so we'll probably need a
>>> git tree similar to the hmm one to synchronize these updates.
>> I'd be willing to just merge this now, if that helps. The conversion
>> is mechanical, and my only slight worry would be that at least for my
>> original patch I didn't build-test the (few) non-x86
>> architecture-specific cases. But I did end up looking at them fairly
>> closely  (basically using some grep/sed scripts to see that the
>> conversions I did matched the same patterns). And your changes look
>> like obvious improvements too where any mistake would have been caught
>> by the compiler.
> I did cross compile the s390 and powerpc bits, but I do not have an
> openrisc compiler.
>
>> So I'm not all that worried from a functionality standpoint, and if
>> this will help the next merge window, I'll happily pull now.
> That would help with this series vs the others, but not with the other
> series vs each other.

Although my series doesn't touch the pagewalk code, it rather borrowed 
some concepts from it and used for the apply_to_page_range() interface.

The reason being that the pagewalk code requires the mmap_sem to be held 
(mainly for trans-huge pages and reading the vma->vm_flags if I 
understand the code correctly). That is fine when you scan the vmas of a 
process, but the helpers I wrote need to instead scan all vmas pointing 
into a struct address_space, and taking the mmap_sem for each vma will 
create lock inversion problems.

/Thomas

Re: [PATCH 2/3] pagewalk: seperate function pointers from iterator data

[Steven Price]

Subject: s/seperate/separate/

On 08/08/2019 16:42, Christoph Hellwig wrote:
> The mm_walk structure currently mixed data and code.  Split out the
> operations vectors into a new mm_walk_ops structure, and while we
> are changing the API also declare the mm_walk structure inside the
> walk_page_range and walk_page_vma functions.
> 
> Based on patch from Linus Torvalds.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  arch/openrisc/kernel/dma.c              |  22 +++--
>  arch/powerpc/mm/book3s64/subpage_prot.c |  10 +-
>  arch/s390/mm/gmap.c                     |  33 +++----
>  fs/proc/task_mmu.c                      |  74 +++++++--------
>  include/linux/pagewalk.h                |  64 +++++++------
>  mm/hmm.c                                |  40 +++-----
>  mm/madvise.c                            |  41 +++-----
>  mm/memcontrol.c                         |  23 +++--
>  mm/mempolicy.c                          |  15 ++-
>  mm/migrate.c                            |  15 ++-
>  mm/mincore.c                            |  15 ++-
>  mm/mprotect.c                           |  24 ++---
>  mm/pagewalk.c                           | 118 ++++++++++++++----------
>  13 files changed, 245 insertions(+), 249 deletions(-)
> 

[...]
> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> index 8a92a961a2ee..28510fc0dde1 100644
> --- a/mm/pagewalk.c
> +++ b/mm/pagewalk.c
> @@ -9,10 +9,11 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
>  {
>  	pte_t *pte;
>  	int err = 0;
> +	const struct mm_walk_ops *ops = walk->ops;
>  
>  	pte = pte_offset_map(pmd, addr);
>  	for (;;) {
> -		err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
> +		err = ops->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
>  		if (err)
>  		       break;
>  		addr += PAGE_SIZE;
> @@ -30,6 +31,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
>  {
>  	pmd_t *pmd;
>  	unsigned long next;
> +	const struct mm_walk_ops *ops = walk->ops;
>  	int err = 0;
>  
>  	pmd = pmd_offset(pud, addr);
> @@ -37,8 +39,8 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
>  again:
>  		next = pmd_addr_end(addr, end);
>  		if (pmd_none(*pmd) || !walk->vma) {
> -			if (walk->pte_hole)
> -				err = walk->pte_hole(addr, next, walk);
> +			if (ops->pte_hole)
> +				err = ops->pte_hole(addr, next, walk);
>  			if (err)
>  				break;
>  			continue;
> @@ -47,8 +49,8 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
>  		 * This implies that each ->pmd_entry() handler
>  		 * needs to know about pmd_trans_huge() pmds
>  		 */
> -		if (walk->pmd_entry)
> -			err = walk->pmd_entry(pmd, addr, next, walk);
> +		if (ops->pmd_entry)
> +			err = ops->pmd_entry(pmd, addr, next, walk);
>  		if (err)
>  			break;
>  
> @@ -56,7 +58,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
>  		 * Check this here so we only break down trans_huge
>  		 * pages when we _need_ to
>  		 */
> -		if (!walk->pte_entry)
> +		if (!ops->pte_entry)
>  			continue;
>  
>  		split_huge_pmd(walk->vma, pmd, addr);
> @@ -75,6 +77,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
>  {
>  	pud_t *pud;
>  	unsigned long next;
> +	const struct mm_walk_ops *ops = walk->ops;
>  	int err = 0;
>  
>  	pud = pud_offset(p4d, addr);
> @@ -82,18 +85,18 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
>   again:
>  		next = pud_addr_end(addr, end);
>  		if (pud_none(*pud) || !walk->vma) {
> -			if (walk->pte_hole)
> -				err = walk->pte_hole(addr, next, walk);
> +			if (ops->pte_hole)
> +				err = ops->pte_hole(addr, next, walk);
>  			if (err)
>  				break;
>  			continue;
>  		}
>  
> -		if (walk->pud_entry) {
> +		if (ops->pud_entry) {
>  			spinlock_t *ptl = pud_trans_huge_lock(pud, walk->vma);
>  
>  			if (ptl) {
> -				err = walk->pud_entry(pud, addr, next, walk);
> +				err = ops->pud_entry(pud, addr, next, walk);
>  				spin_unlock(ptl);
>  				if (err)
>  					break;
> @@ -105,7 +108,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end,
>  		if (pud_none(*pud))
>  			goto again;
>  
> -		if (walk->pmd_entry || walk->pte_entry)
> +		if (ops->pmd_entry || ops->pte_entry)
>  			err = walk_pmd_range(pud, addr, next, walk);
>  		if (err)
>  			break;
> @@ -119,19 +122,20 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
>  {
>  	p4d_t *p4d;
>  	unsigned long next;
> +	const struct mm_walk_ops *ops = walk->ops;
>  	int err = 0;
>  
>  	p4d = p4d_offset(pgd, addr);
>  	do {
>  		next = p4d_addr_end(addr, end);
>  		if (p4d_none_or_clear_bad(p4d)) {
> -			if (walk->pte_hole)
> -				err = walk->pte_hole(addr, next, walk);
> +			if (ops->pte_hole)
> +				err = ops->pte_hole(addr, next, walk);
>  			if (err)
>  				break;
>  			continue;
>  		}
> -		if (walk->pmd_entry || walk->pte_entry)
> +		if (ops->pmd_entry || ops->pte_entry)
>  			err = walk_pud_range(p4d, addr, next, walk);
>  		if (err)
>  			break;
> @@ -145,19 +149,20 @@ static int walk_pgd_range(unsigned long addr, unsigned long end,
>  {
>  	pgd_t *pgd;
>  	unsigned long next;
> +	const struct mm_walk_ops *ops = walk->ops;
>  	int err = 0;
>  
>  	pgd = pgd_offset(walk->mm, addr);
>  	do {
>  		next = pgd_addr_end(addr, end);
>  		if (pgd_none_or_clear_bad(pgd)) {
> -			if (walk->pte_hole)
> -				err = walk->pte_hole(addr, next, walk);
> +			if (ops->pte_hole)
> +				err = ops->pte_hole(addr, next, walk);
>  			if (err)
>  				break;
>  			continue;
>  		}
> -		if (walk->pmd_entry || walk->pte_entry)
> +		if (ops->pmd_entry || ops->pte_entry)
>  			err = walk_p4d_range(pgd, addr, next, walk);
>  		if (err)
>  			break;
> @@ -183,6 +188,7 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
>  	unsigned long hmask = huge_page_mask(h);
>  	unsigned long sz = huge_page_size(h);
>  	pte_t *pte;
> +	const struct mm_walk_ops *ops = walk->ops;
>  	int err = 0;
>  
>  	do {
> @@ -190,9 +196,9 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
>  		pte = huge_pte_offset(walk->mm, addr & hmask, sz);
>  
>  		if (pte)
> -			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
> -		else if (walk->pte_hole)
> -			err = walk->pte_hole(addr, next, walk);
> +			err = ops->hugetlb_entry(pte, hmask, addr, next, walk);
> +		else if (ops->pte_hole)
> +			err = ops->pte_hole(addr, next, walk);
>  
>  		if (err)
>  			break;
> @@ -220,9 +226,10 @@ static int walk_page_test(unsigned long start, unsigned long end,
>  			struct mm_walk *walk)
>  {
>  	struct vm_area_struct *vma = walk->vma;
> +	const struct mm_walk_ops *ops = walk->ops;
>  
> -	if (walk->test_walk)
> -		return walk->test_walk(start, end, walk);
> +	if (ops->test_walk)
> +		return ops->test_walk(start, end, walk);
>  
>  	/*
>  	 * vma(VM_PFNMAP) doesn't have any valid struct pages behind VM_PFNMAP
> @@ -234,8 +241,8 @@ static int walk_page_test(unsigned long start, unsigned long end,
>  	 */
>  	if (vma->vm_flags & VM_PFNMAP) {
>  		int err = 1;
> -		if (walk->pte_hole)
> -			err = walk->pte_hole(start, end, walk);
> +		if (ops->pte_hole)
> +			err = ops->pte_hole(start, end, walk);
>  		return err ? err : 1;
>  	}
>  	return 0;
> @@ -248,7 +255,8 @@ static int __walk_page_range(unsigned long start, unsigned long end,
>  	struct vm_area_struct *vma = walk->vma;
>  
>  	if (vma && is_vm_hugetlb_page(vma)) {
> -		if (walk->hugetlb_entry)
> +		const struct mm_walk_ops *ops = walk->ops;

NIT: checkpatch would like a blank line here

> +		if (ops->hugetlb_entry)
>  			err = walk_hugetlb_range(start, end, walk);
>  	} else
>  		err = walk_pgd_range(start, end, walk);
> @@ -258,11 +266,13 @@ static int __walk_page_range(unsigned long start, unsigned long end,
>  
>  /**
>   * walk_page_range - walk page table with caller specific callbacks
> - * @start: start address of the virtual address range
> - * @end: end address of the virtual address range
> - * @walk: mm_walk structure defining the callbacks and the target address space
> + * @mm:		mm_struct representing the target process of page table walk
> + * @start:	start address of the virtual address range
> + * @end:	end address of the virtual address range
> + * @ops:	operation to call during the walk
> + * @private:	private data for callbacks' usage
>   *
> - * Recursively walk the page table tree of the process represented by @walk->mm
> + * Recursively walk the page table tree of the process represented by @mm
>   * within the virtual address range [@start, @end). During walking, we can do
>   * some caller-specific works for each entry, by setting up pmd_entry(),
>   * pte_entry(), and/or hugetlb_entry(). If you don't set up for some of these

Missing context:
>  *
>  * Before starting to walk page table, some callers want to check whether
>  * they really want to walk over the current vma, typically by checking
>  * its vm_flags. walk_page_test() and @walk->test_walk() are used for this
>  * purpose.

@walk->test_walk() should now be @ops->test_walk()

> @@ -283,42 +293,48 @@ static int __walk_page_range(unsigned long start, unsigned long end,
>   *
>   * struct mm_walk keeps current values of some common data like vma and pmd,
>   * which are useful for the access from callbacks. If you want to pass some
> - * caller-specific data to callbacks, @walk->private should be helpful.
> + * caller-specific data to callbacks, @private should be helpful.
>   *
>   * Locking:
>   *   Callers of walk_page_range() and walk_page_vma() should hold
>   *   @walk->mm->mmap_sem, because these function traverse vma list and/or

s/walk->//

Otherwise looks good - I've rebased my series on it and the initial
testing is fine. So for the series:

Reviewed-by: Steven Price <steven.price@arm.com>

Thanks,

Steve

Re: cleanup the walk_page_range interface

[Christoph Hellwig]

On Fri, Aug 09, 2019 at 12:21:24AM +0200, Thomas Hellstrom wrote:
> On 8/8/19 11:56 PM, Christoph Hellwig wrote:
>> On Thu, Aug 08, 2019 at 10:50:37AM -0700, Linus Torvalds wrote:
>>>> Note that both Thomas and Steven have series touching this area pending,
>>>> and there are a couple consumer in flux too - the hmm tree already
>>>> conflicts with this series, and I have potential dma changes on top of
>>>> the consumers in Thomas and Steven's series, so we'll probably need a
>>>> git tree similar to the hmm one to synchronize these updates.
>>> I'd be willing to just merge this now, if that helps. The conversion
>>> is mechanical, and my only slight worry would be that at least for my
>>> original patch I didn't build-test the (few) non-x86
>>> architecture-specific cases. But I did end up looking at them fairly
>>> closely  (basically using some grep/sed scripts to see that the
>>> conversions I did matched the same patterns). And your changes look
>>> like obvious improvements too where any mistake would have been caught
>>> by the compiler.
>> I did cross compile the s390 and powerpc bits, but I do not have an
>> openrisc compiler.
>>
>>> So I'm not all that worried from a functionality standpoint, and if
>>> this will help the next merge window, I'll happily pull now.
>> That would help with this series vs the others, but not with the other
>> series vs each other.
>
> Although my series doesn't touch the pagewalk code, it rather borrowed some 
> concepts from it and used for the apply_to_page_range() interface.
>
> The reason being that the pagewalk code requires the mmap_sem to be held 
> (mainly for trans-huge pages and reading the vma->vm_flags if I understand 
> the code correctly). That is fine when you scan the vmas of a process, but 
> the helpers I wrote need to instead scan all vmas pointing into a struct 
> address_space, and taking the mmap_sem for each vma will create lock 
> inversion problems.


True.  So you'll just need to apply the same lessons there, and we
should probably fine with this series going into 5.3-rc.

Re: cleanup the walk_page_range interface

[Mike Rapoport]

On Thu, Aug 08, 2019 at 11:56:32PM +0200, Christoph Hellwig wrote:
> On Thu, Aug 08, 2019 at 10:50:37AM -0700, Linus Torvalds wrote:
> > > Note that both Thomas and Steven have series touching this area pending,
> > > and there are a couple consumer in flux too - the hmm tree already
> > > conflicts with this series, and I have potential dma changes on top of
> > > the consumers in Thomas and Steven's series, so we'll probably need a
> > > git tree similar to the hmm one to synchronize these updates.
> > 
> > I'd be willing to just merge this now, if that helps. The conversion
> > is mechanical, and my only slight worry would be that at least for my
> > original patch I didn't build-test the (few) non-x86
> > architecture-specific cases. But I did end up looking at them fairly
> > closely  (basically using some grep/sed scripts to see that the
> > conversions I did matched the same patterns). And your changes look
> > like obvious improvements too where any mistake would have been caught
> > by the compiler.
> 
> I did cross compile the s390 and powerpc bits, but I do not have an
> openrisc compiler.

The openrisc defconfig builds fine.
 
> > So I'm not all that worried from a functionality standpoint, and if
> > this will help the next merge window, I'll happily pull now.
> 
> That would help with this series vs the others, but not with the other
> series vs each other.
> 

-- 
Sincerely yours,
Mike.

Re: cleanup the walk_page_range interface

[Christoph Hellwig]

On Thu, Aug 08, 2019 at 10:50:37AM -0700, Linus Torvalds wrote:
> On Thu, Aug 8, 2019 at 8:42 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > this series is based on a patch from Linus to split the callbacks
> > passed to walk_page_range and walk_page_vma into a separate structure
> > that can be marked const, with various cleanups from me on top.
> 
> The whole series looks good to me. Ack.
> 
> > Note that both Thomas and Steven have series touching this area pending,
> > and there are a couple consumer in flux too - the hmm tree already
> > conflicts with this series, and I have potential dma changes on top of
> > the consumers in Thomas and Steven's series, so we'll probably need a
> > git tree similar to the hmm one to synchronize these updates.
> 
> I'd be willing to just merge this now, if that helps. The conversion
> is mechanical, and my only slight worry would be that at least for my
> original patch I didn't build-test the (few) non-x86
> architecture-specific cases. But I did end up looking at them fairly
> closely  (basically using some grep/sed scripts to see that the
> conversions I did matched the same patterns). And your changes look
> like obvious improvements too where any mistake would have been caught
> by the compiler.
> 
> So I'm not all that worried from a functionality standpoint, and if
> this will help the next merge window, I'll happily pull now.

So what is the plan forward?  Probably a little late for 5.3,
so queue it up in -mm for 5.4 and deal with the conflicts in at least
hmm?  Queue it up in the hmm tree even if it doesn't 100% fit?

Re: cleanup the walk_page_range interface

[Jason Gunthorpe]

On Thu, Aug 15, 2019 at 11:27:51PM -0700, Christoph Hellwig wrote:
> On Thu, Aug 08, 2019 at 10:50:37AM -0700, Linus Torvalds wrote:
> > On Thu, Aug 8, 2019 at 8:42 AM Christoph Hellwig <hch@lst.de> wrote:
> > >
> > > this series is based on a patch from Linus to split the callbacks
> > > passed to walk_page_range and walk_page_vma into a separate structure
> > > that can be marked const, with various cleanups from me on top.
> > 
> > The whole series looks good to me. Ack.
> > 
> > > Note that both Thomas and Steven have series touching this area pending,
> > > and there are a couple consumer in flux too - the hmm tree already
> > > conflicts with this series, and I have potential dma changes on top of
> > > the consumers in Thomas and Steven's series, so we'll probably need a
> > > git tree similar to the hmm one to synchronize these updates.
> > 
> > I'd be willing to just merge this now, if that helps. The conversion
> > is mechanical, and my only slight worry would be that at least for my
> > original patch I didn't build-test the (few) non-x86
> > architecture-specific cases. But I did end up looking at them fairly
> > closely  (basically using some grep/sed scripts to see that the
> > conversions I did matched the same patterns). And your changes look
> > like obvious improvements too where any mistake would have been caught
> > by the compiler.
> > 
> > So I'm not all that worried from a functionality standpoint, and if
> > this will help the next merge window, I'll happily pull now.
> 
> So what is the plan forward?  Probably a little late for 5.3,
> so queue it up in -mm for 5.4 and deal with the conflicts in at least
> hmm?  Queue it up in the hmm tree even if it doesn't 100% fit?

Are there conflicts with trees other than hmm?

We can put it on a topic branch and merge to hmm to resolve. If hmm
has problems then send the topic on its own?

Jason

Re: cleanup the walk_page_range interface

[Christoph Hellwig]

On Fri, Aug 16, 2019 at 11:57:40AM +0000, Jason Gunthorpe wrote:
> Are there conflicts with trees other than hmm?
> 
> We can put it on a topic branch and merge to hmm to resolve. If hmm
> has problems then send the topic on its own?

I see two new walk_page_range user in linux-next related to MADV_COLD
support (which probably really should use walk_range_vma), and then
there is the series from Steven, which hasn't been merged yet.

Re: cleanup the walk_page_range interface

[Linus Torvalds]

On Fri, Aug 16, 2019 at 5:33 AM Christoph Hellwig <hch@lst.de> wrote:
>
> I see two new walk_page_range user in linux-next related to MADV_COLD
> support (which probably really should use walk_range_vma), and then
> there is the series from Steven, which hasn't been merged yet.

It does sound like this might as well just be handled in linux-next,
and there's no big advantage in me pulling the walker cleanups early.

Honestly, even if it ends up being handled as a conflict resolution
issue (rather than some shared branch), it probably simply isn't all
that painful. We have those kinds of semantic conflicts all the time,
it doesn't worry me too much.

So I'm not worried about new _users_ of the page walker concurrently
with the page walker interface itself being cleaned up. Those kinds of
conflicts end up being "just make sure to update the new users to the
new interface when they get pulled". Happens all the time.

I'd be more worried about two different branches wanting to change the
internal implementation of the page walker itself, and the actual
*code* itself getting conflicts (as opposed to the interface vs users
kind of conflicts). Those kinds of conflicts can be messy. But it
sounds like Thomas Hellström's changes aren't that kind of thing.

I'm still willing to do the early merge if it turns out to be hugely
helpful, but from the discussion so far it does sound like "just merge
during 5.4 merge window" is perfectly fine.

               Linus

Re: cleanup the walk_page_range interface

[Andrew Morton]

On Fri, 16 Aug 2019 14:32:58 +0200 Christoph Hellwig <hch@lst.de> wrote:

> On Fri, Aug 16, 2019 at 11:57:40AM +0000, Jason Gunthorpe wrote:
> > Are there conflicts with trees other than hmm?
> > 
> > We can put it on a topic branch and merge to hmm to resolve. If hmm
> > has problems then send the topic on its own?
> 
> I see two new walk_page_range user in linux-next related to MADV_COLD
> support (which probably really should use walk_range_vma), and then
> there is the series from Steven, which hasn't been merged yet.

Would it be practical to create a brand new interface with different
functions names all in new source files?  Once all callers are migrated
over and tested, remove the old code?

Re: cleanup the walk_page_range interface

[Stephen Rothwell]

[-- Attachment #1: Type: text/plain, Size: 1196 bytes --]

Hi all,

On Fri, 16 Aug 2019 14:06:23 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Fri, 16 Aug 2019 14:32:58 +0200 Christoph Hellwig <hch@lst.de> wrote:
> 
> > On Fri, Aug 16, 2019 at 11:57:40AM +0000, Jason Gunthorpe wrote:  
> > > Are there conflicts with trees other than hmm?
> > > 
> > > We can put it on a topic branch and merge to hmm to resolve. If hmm
> > > has problems then send the topic on its own?  
> > 
> > I see two new walk_page_range user in linux-next related to MADV_COLD
> > support (which probably really should use walk_range_vma), and then
> > there is the series from Steven, which hasn't been merged yet.  
> 
> Would it be practical to create a brand new interface with different
> functions names all in new source files?  Once all callers are migrated
> over and tested, remove the old code?

I certainly prefer that method of API change :-)
(see the current "keys: Replace uid/gid/perm permissions checking with
an ACL" in linux-next and the (currently) three merge fixup patches I
am carrying.  Its not bad when people provide the fixes, but I am no
expert in most areas of the kernel ...)
-- 
Cheers,
Stephen Rothwell

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: cleanup the walk_page_range interface

[Christoph Hellwig]

On Sat, Aug 17, 2019 at 04:41:24PM +1000, Stephen Rothwell wrote:
> I certainly prefer that method of API change :-)
> (see the current "keys: Replace uid/gid/perm permissions checking with
> an ACL" in linux-next and the (currently) three merge fixup patches I
> am carrying.  Its not bad when people provide the fixes, but I am no
> expert in most areas of the kernel ...)

It would mean pretty much duplicating all the code.  And then never
finish the migration because new users of the old interfaces keep
popping up.  Compared to that I'd much much prefer either Linus
taking it now or a branch.

Re: cleanup the walk_page_range interface

[Stephen Rothwell]

[-- Attachment #1: Type: text/plain, Size: 975 bytes --]

Hi Christoph,

On Sat, 17 Aug 2019 08:43:01 +0200 Christoph Hellwig <hch@lst.de> wrote:
>
> On Sat, Aug 17, 2019 at 04:41:24PM +1000, Stephen Rothwell wrote:
> > I certainly prefer that method of API change :-)
> > (see the current "keys: Replace uid/gid/perm permissions checking with
> > an ACL" in linux-next and the (currently) three merge fixup patches I
> > am carrying.  Its not bad when people provide the fixes, but I am no
> > expert in most areas of the kernel ...)  
> 
> It would mean pretty much duplicating all the code.  And then never
> finish the migration because new users of the old interfaces keep
> popping up.  Compared to that I'd much much prefer either Linus
> taking it now or a branch.

Sure, I have no problem with either of these two choices, or, at least,
hints/resolutions when conflicts are expected.  My time (each day) is
already getting pretty short since we are almost up to -rc5 ...

-- 
Cheers,
Stephen Rothwell

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: cleanup the walk_page_range interface

[Linus Torvalds]

On Fri, Aug 16, 2019 at 11:41 PM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> I certainly prefer that method of API change :-)
> (see the current "keys: Replace uid/gid/perm permissions checking with
> an ACL" in linux-next

Side note: I will *not* be pulling that again.

It was broken last time, and without more people reviewing the code,
I' m not pulling it for 5.4 either even if David has an additional
commit on top that might have fixed the original problem.

There's still a pending kernel test report on commit f771fde82051
("keys: Simplify key description management") from another of David's
pulls for 5.3 - one that didn't get reverted.

David, look in your inbox for a kernel test report about

  kernel BUG at security/keys/keyring.c:1245!

(It's the

        BUG_ON(index_key->desc_len == 0);

line - the line numbers have since changed, and it's line 1304 in the
current tree).

I'm not sure why _that_ BUG_ON() now triggers, but I wonder if it's
because 'desc_len' went from a 'size_t' to an 'u8', and now a desc_len
of 256 is 0. Or something. The point being that there have been too
many bugs in the pulls and nobody but David apparently ever had
anything to do with any of the development. This code needs more eyes,
not more random changes.

So I won't be compounding on that workflow problem next merge window.

                  Linus

Re: cleanup the walk_page_range interface

[Jason Gunthorpe]

On Thu, Aug 15, 2019 at 11:27:51PM -0700, Christoph Hellwig wrote:
> On Thu, Aug 08, 2019 at 10:50:37AM -0700, Linus Torvalds wrote:
> > On Thu, Aug 8, 2019 at 8:42 AM Christoph Hellwig <hch@lst.de> wrote:
> > >
> > > this series is based on a patch from Linus to split the callbacks
> > > passed to walk_page_range and walk_page_vma into a separate structure
> > > that can be marked const, with various cleanups from me on top.
> > 
> > The whole series looks good to me. Ack.
> > 
> > > Note that both Thomas and Steven have series touching this area pending,
> > > and there are a couple consumer in flux too - the hmm tree already
> > > conflicts with this series, and I have potential dma changes on top of
> > > the consumers in Thomas and Steven's series, so we'll probably need a
> > > git tree similar to the hmm one to synchronize these updates.
> > 
> > I'd be willing to just merge this now, if that helps. The conversion
> > is mechanical, and my only slight worry would be that at least for my
> > original patch I didn't build-test the (few) non-x86
> > architecture-specific cases. But I did end up looking at them fairly
> > closely  (basically using some grep/sed scripts to see that the
> > conversions I did matched the same patterns). And your changes look
> > like obvious improvements too where any mistake would have been caught
> > by the compiler.
> > 
> > So I'm not all that worried from a functionality standpoint, and if
> > this will help the next merge window, I'll happily pull now.
> 
> So what is the plan forward?  Probably a little late for 5.3,
> so queue it up in -mm for 5.4 and deal with the conflicts in at least
> hmm?  Queue it up in the hmm tree even if it doesn't 100% fit?

Did we make a decision on this? Due to travel & LPC I'd like to
finalize the hmm tree next week.

Thanks,
Jason

Re: cleanup the walk_page_range interface

[Steven Price]

On 23/08/2019 14:43, Jason Gunthorpe wrote:
> On Thu, Aug 15, 2019 at 11:27:51PM -0700, Christoph Hellwig wrote:
>> On Thu, Aug 08, 2019 at 10:50:37AM -0700, Linus Torvalds wrote:
>>> On Thu, Aug 8, 2019 at 8:42 AM Christoph Hellwig <hch@lst.de> wrote:
>>>>
>>>> this series is based on a patch from Linus to split the callbacks
>>>> passed to walk_page_range and walk_page_vma into a separate structure
>>>> that can be marked const, with various cleanups from me on top.
>>>
>>> The whole series looks good to me. Ack.
>>>
>>>> Note that both Thomas and Steven have series touching this area pending,
>>>> and there are a couple consumer in flux too - the hmm tree already
>>>> conflicts with this series, and I have potential dma changes on top of
>>>> the consumers in Thomas and Steven's series, so we'll probably need a
>>>> git tree similar to the hmm one to synchronize these updates.
>>>
>>> I'd be willing to just merge this now, if that helps. The conversion
>>> is mechanical, and my only slight worry would be that at least for my
>>> original patch I didn't build-test the (few) non-x86
>>> architecture-specific cases. But I did end up looking at them fairly
>>> closely  (basically using some grep/sed scripts to see that the
>>> conversions I did matched the same patterns). And your changes look
>>> like obvious improvements too where any mistake would have been caught
>>> by the compiler.
>>>
>>> So I'm not all that worried from a functionality standpoint, and if
>>> this will help the next merge window, I'll happily pull now.
>>
>> So what is the plan forward?  Probably a little late for 5.3,
>> so queue it up in -mm for 5.4 and deal with the conflicts in at least
>> hmm?  Queue it up in the hmm tree even if it doesn't 100% fit?
> 
> Did we make a decision on this? Due to travel & LPC I'd like to
> finalize the hmm tree next week.

I was planning on rebasing my series on this and posting it for 5.4 - I
hadn't actually realised this hasn't been picked up yet. I haven't had
much time to look at this recently.

FWIW you can add for the series:

Acked-by: Steven Price <steven.price@arm.com>

Steve

Re: cleanup the walk_page_range interface

[Christoph Hellwig]

On Fri, Aug 23, 2019 at 01:43:12PM +0000, Jason Gunthorpe wrote:
> > So what is the plan forward?  Probably a little late for 5.3,
> > so queue it up in -mm for 5.4 and deal with the conflicts in at least
> > hmm?  Queue it up in the hmm tree even if it doesn't 100% fit?
> 
> Did we make a decision on this? Due to travel & LPC I'd like to
> finalize the hmm tree next week.

I don't think we've made any decision.  I'd still love to see this
in hmm.git.  It has a minor conflict, but I can resend a rebased
version.

Re: cleanup the walk_page_range interface

[Jason Gunthorpe]

On Sat, Aug 24, 2019 at 03:26:55PM -0700, Christoph Hellwig wrote:
> On Fri, Aug 23, 2019 at 01:43:12PM +0000, Jason Gunthorpe wrote:
> > > So what is the plan forward?  Probably a little late for 5.3,
> > > so queue it up in -mm for 5.4 and deal with the conflicts in at least
> > > hmm?  Queue it up in the hmm tree even if it doesn't 100% fit?
> > 
> > Did we make a decision on this? Due to travel & LPC I'd like to
> > finalize the hmm tree next week.
> 
> I don't think we've made any decision.  I'd still love to see this
> in hmm.git.  It has a minor conflict, but I can resend a rebased
> version.

I'm looking at this.. The hmm conflict is easy enough to fix.

But the compile conflict with these two patches in -mm requires some
action from Andrew:

commit 027b9b8fd9ee3be6b7440462102ec03a2d593213
Author: Minchan Kim <minchan@kernel.org>
Date:   Sun Aug 25 11:49:27 2019 +1000

    mm: introduce MADV_PAGEOUT

commit f227453a14cadd4727dd159782531d617f257001
Author: Minchan Kim <minchan@kernel.org>
Date:   Sun Aug 25 11:49:27 2019 +1000

    mm: introduce MADV_COLD
    
    Patch series "Introduce MADV_COLD and MADV_PAGEOUT", v7.

I'm inclined to suggest you send this series in the 2nd half of the
merge window after this MADV stuff lands for least disruption? 

Thanks,
Jason

Re: cleanup the walk_page_range interface

[Andrew Morton]

On Tue, 27 Aug 2019 01:34:13 +0000 Jason Gunthorpe <jgg@mellanox.com> wrote:

> On Sat, Aug 24, 2019 at 03:26:55PM -0700, Christoph Hellwig wrote:
> > On Fri, Aug 23, 2019 at 01:43:12PM +0000, Jason Gunthorpe wrote:
> > > > So what is the plan forward?  Probably a little late for 5.3,
> > > > so queue it up in -mm for 5.4 and deal with the conflicts in at least
> > > > hmm?  Queue it up in the hmm tree even if it doesn't 100% fit?
> > > 
> > > Did we make a decision on this? Due to travel & LPC I'd like to
> > > finalize the hmm tree next week.
> > 
> > I don't think we've made any decision.  I'd still love to see this
> > in hmm.git.  It has a minor conflict, but I can resend a rebased
> > version.
> 
> I'm looking at this.. The hmm conflict is easy enough to fix.
> 
> But the compile conflict with these two patches in -mm requires some
> action from Andrew:
> 
> commit 027b9b8fd9ee3be6b7440462102ec03a2d593213
> Author: Minchan Kim <minchan@kernel.org>
> Date:   Sun Aug 25 11:49:27 2019 +1000
> 
>     mm: introduce MADV_PAGEOUT
> 
> commit f227453a14cadd4727dd159782531d617f257001
> Author: Minchan Kim <minchan@kernel.org>
> Date:   Sun Aug 25 11:49:27 2019 +1000
> 
>     mm: introduce MADV_COLD
>     
>     Patch series "Introduce MADV_COLD and MADV_PAGEOUT", v7.
> 
> I'm inclined to suggest you send this series in the 2nd half of the
> merge window after this MADV stuff lands for least disruption? 

Just merge it, I'll figure it out.  Probably by staging Minchan's
patches after linux-next.

Re: cleanup the walk_page_range interface

[Jason Gunthorpe]

On Tue, Aug 27, 2019 at 04:34:31PM -0700, Andrew Morton wrote:
> On Tue, 27 Aug 2019 01:34:13 +0000 Jason Gunthorpe <jgg@mellanox.com> wrote:
> 
> > On Sat, Aug 24, 2019 at 03:26:55PM -0700, Christoph Hellwig wrote:
> > > On Fri, Aug 23, 2019 at 01:43:12PM +0000, Jason Gunthorpe wrote:
> > > > > So what is the plan forward?  Probably a little late for 5.3,
> > > > > so queue it up in -mm for 5.4 and deal with the conflicts in at least
> > > > > hmm?  Queue it up in the hmm tree even if it doesn't 100% fit?
> > > > 
> > > > Did we make a decision on this? Due to travel & LPC I'd like to
> > > > finalize the hmm tree next week.
> > > 
> > > I don't think we've made any decision.  I'd still love to see this
> > > in hmm.git.  It has a minor conflict, but I can resend a rebased
> > > version.
> > 
> > I'm looking at this.. The hmm conflict is easy enough to fix.
> > 
> > But the compile conflict with these two patches in -mm requires some
> > action from Andrew:
> > 
> > commit 027b9b8fd9ee3be6b7440462102ec03a2d593213
> > Author: Minchan Kim <minchan@kernel.org>
> > Date:   Sun Aug 25 11:49:27 2019 +1000
> > 
> >     mm: introduce MADV_PAGEOUT
> > 
> > commit f227453a14cadd4727dd159782531d617f257001
> > Author: Minchan Kim <minchan@kernel.org>
> > Date:   Sun Aug 25 11:49:27 2019 +1000
> > 
> >     mm: introduce MADV_COLD
> >     
> >     Patch series "Introduce MADV_COLD and MADV_PAGEOUT", v7.
> > 
> > I'm inclined to suggest you send this series in the 2nd half of the
> > merge window after this MADV stuff lands for least disruption? 
> 
> Just merge it, I'll figure it out.  Probably by staging Minchan's
> patches after linux-next.

Okay, I'll get it on a branch and merge it toward hmm.git tomorrow

Steven, do you need the branch as well for your patch series? Let me know

Thanks,
Jason

Re: cleanup the walk_page_range interface

[Christoph Hellwig]

On Tue, Aug 27, 2019 at 11:36:26PM +0000, Jason Gunthorpe wrote:
> Okay, I'll get it on a branch and merge it toward hmm.git tomorrow

I was planning to resend it with the rebase, especially as the build
bot picked a build error in task_mmu.c where we were missing a stub
for an unusual configuration.  I wish I'd remember which one that was..

Re: cleanup the walk_page_range interface

[Steven Price]

On 28/08/2019 00:36, Jason Gunthorpe wrote:
> On Tue, Aug 27, 2019 at 04:34:31PM -0700, Andrew Morton wrote:
>> On Tue, 27 Aug 2019 01:34:13 +0000 Jason Gunthorpe <jgg@mellanox.com> wrote:
>>
>>> On Sat, Aug 24, 2019 at 03:26:55PM -0700, Christoph Hellwig wrote:
>>>> On Fri, Aug 23, 2019 at 01:43:12PM +0000, Jason Gunthorpe wrote:
>>>>>> So what is the plan forward?  Probably a little late for 5.3,
>>>>>> so queue it up in -mm for 5.4 and deal with the conflicts in at least
>>>>>> hmm?  Queue it up in the hmm tree even if it doesn't 100% fit?
>>>>>
>>>>> Did we make a decision on this? Due to travel & LPC I'd like to
>>>>> finalize the hmm tree next week.
>>>>
>>>> I don't think we've made any decision.  I'd still love to see this
>>>> in hmm.git.  It has a minor conflict, but I can resend a rebased
>>>> version.
>>>
>>> I'm looking at this.. The hmm conflict is easy enough to fix.
>>>
>>> But the compile conflict with these two patches in -mm requires some
>>> action from Andrew:
>>>
>>> commit 027b9b8fd9ee3be6b7440462102ec03a2d593213
>>> Author: Minchan Kim <minchan@kernel.org>
>>> Date:   Sun Aug 25 11:49:27 2019 +1000
>>>
>>>     mm: introduce MADV_PAGEOUT
>>>
>>> commit f227453a14cadd4727dd159782531d617f257001
>>> Author: Minchan Kim <minchan@kernel.org>
>>> Date:   Sun Aug 25 11:49:27 2019 +1000
>>>
>>>     mm: introduce MADV_COLD
>>>     
>>>     Patch series "Introduce MADV_COLD and MADV_PAGEOUT", v7.
>>>
>>> I'm inclined to suggest you send this series in the 2nd half of the
>>> merge window after this MADV stuff lands for least disruption? 
>>
>> Just merge it, I'll figure it out.  Probably by staging Minchan's
>> patches after linux-next.
> 
> Okay, I'll get it on a branch and merge it toward hmm.git tomorrow
> 
> Steven, do you need the branch as well for your patch series? Let me know

Since my series is (mostly) just refactoring I'm planning on rebasing it
after -rc1 and aim for v5.4 - I don't really have the time just now to
do that.

But please keep me in the loop because it'll reduce the surprises when I
do do the rebase.

Thanks,

Steve