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[PATCH v11 01/14] fork: pass the dst vma to copy_page_range() and its sub-functions.

From Jérôme Glisse <jglisse@redhat.com>
Newsgroups linux.kernel
Subject [PATCH v11 01/14] fork: pass the dst vma to copy_page_range() and its sub-functions.
Date 2015-10-21 22:30 +0200
Message-ID <qm8bf-5ry-9@gated-at.bofh.it> (permalink)
References <qm81A-5gx-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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For HMM we will need to resort to the old way of allocating new page
for anonymous memory when that anonymous memory have been migrated
to device memory.

This does not impact any process that do not use HMM through some
device driver. Only process that migrate anonymous memory to device
memory with HMM will have to copy migrated page on fork.

We do not expect this to be a common or advised thing to do so we
resort to the simpler solution of allocating new page. If this kind
of usage turns out to be important we will revisit way to achieve
COW even for remote memory.

Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
---
 include/linux/mm.h |  5 +++--
 kernel/fork.c      |  2 +-
 mm/memory.c        | 33 +++++++++++++++++++++------------
 3 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6f967a1..18f27afd 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1162,8 +1162,9 @@ int walk_page_range(unsigned long addr, unsigned long end,
 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,
-			struct vm_area_struct *vma);
+int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+		    struct vm_area_struct *dst_vma,
+		    struct vm_area_struct *vma);
 void unmap_mapping_range(struct address_space *mapping,
 		loff_t const holebegin, loff_t const holelen, int even_cows);
 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
diff --git a/kernel/fork.c b/kernel/fork.c
index 631c398..74ad33c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -498,7 +498,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
 		rb_parent = &tmp->vm_rb;
 
 		mm->map_count++;
-		retval = copy_page_range(mm, oldmm, mpnt);
+		retval = copy_page_range(mm, oldmm, tmp, mpnt);
 
 		if (tmp->vm_ops && tmp->vm_ops->open)
 			tmp->vm_ops->open(tmp);
diff --git a/mm/memory.c b/mm/memory.c
index 77bbbf3..bbab5e9 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -886,8 +886,10 @@ out_set_pte:
 }
 
 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
-		   pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
-		   unsigned long addr, unsigned long end)
+			  pmd_t *dst_pmd, pmd_t *src_pmd,
+			  struct vm_area_struct *dst_vma,
+			  struct vm_area_struct *vma,
+			  unsigned long addr, unsigned long end)
 {
 	pte_t *orig_src_pte, *orig_dst_pte;
 	pte_t *src_pte, *dst_pte;
@@ -948,9 +950,12 @@ again:
 	return 0;
 }
 
-static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
-		pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
-		unsigned long addr, unsigned long end)
+static inline int copy_pmd_range(struct mm_struct *dst_mm,
+				 struct mm_struct *src_mm,
+				 pud_t *dst_pud, pud_t *src_pud,
+				 struct vm_area_struct *dst_vma,
+				 struct vm_area_struct *vma,
+				 unsigned long addr, unsigned long end)
 {
 	pmd_t *src_pmd, *dst_pmd;
 	unsigned long next;
@@ -975,15 +980,18 @@ static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src
 		if (pmd_none_or_clear_bad(src_pmd))
 			continue;
 		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
-						vma, addr, next))
+				   dst_vma, vma, addr, next))
 			return -ENOMEM;
 	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
 	return 0;
 }
 
-static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
-		pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
-		unsigned long addr, unsigned long end)
+static inline int copy_pud_range(struct mm_struct *dst_mm,
+				 struct mm_struct *src_mm,
+				 pgd_t *dst_pgd, pgd_t *src_pgd,
+				 struct vm_area_struct *dst_vma,
+				 struct vm_area_struct *vma,
+				 unsigned long addr, unsigned long end)
 {
 	pud_t *src_pud, *dst_pud;
 	unsigned long next;
@@ -997,14 +1005,15 @@ static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src
 		if (pud_none_or_clear_bad(src_pud))
 			continue;
 		if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
-						vma, addr, next))
+				   dst_vma, vma, addr, next))
 			return -ENOMEM;
 	} while (dst_pud++, src_pud++, addr = next, addr != end);
 	return 0;
 }
 
 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
-		struct vm_area_struct *vma)
+		    struct vm_area_struct *dst_vma,
+		    struct vm_area_struct *vma)
 {
 	pgd_t *src_pgd, *dst_pgd;
 	unsigned long next;
@@ -1058,7 +1067,7 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		if (pgd_none_or_clear_bad(src_pgd))
 			continue;
 		if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
-					    vma, addr, next))) {
+					    dst_vma, vma, addr, next))) {
 			ret = -ENOMEM;
 			break;
 		}
-- 
2.4.3

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Thread

[PATCH v11 00/14] HMM anomymous memory migration to device memory Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 07/14] HMM: mm add helper to update page table when migrating memory v2. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 06/14] HMM: mm add helper to update page table when migrating memory back v2. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 05/14] HMM: handle HMM device page table entry on mirror page table fault and update. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 11/14] HMM: add helpers for migration back to system memory v3. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 02/14] HMM: add special swap filetype for memory migrated to device v2. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 14/14] HMM: add mirror fault support for system to device memory migration v3. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 09/14] HMM: allow to get pointer to spinlock protecting a directory. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 04/14] HMM: add new HMM page table flag (select flag). Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 13/14] HMM: CPU page fault on migrated memory. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 10/14] HMM: split DMA mapping function in two. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 12/14] HMM: fork copy migrated memory into system memory for child process. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:20 +0200
  [PATCH v11 08/14] HMM: new callback for copying memory from and to device memory v2. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:30 +0200
  [PATCH v11 01/14] fork: pass the dst vma to copy_page_range() and its sub-functions. Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:30 +0200
  [PATCH v11 03/14] HMM: add new HMM page table flag (valid device memory). Jérôme Glisse <jglisse@redhat.com> - 2015-10-21 22:30 +0200

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