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Subject[PATCHv10 2.6.35-rc6-tip 1/14] mm: Move replace_page() / write_protect_page() to mm/memory.c

User bkpt will use background page replacement approach to insert/delete
breakpoints. Background page replacement approach will be based on
replace_page and write_protect_page.
Now replace_page() loses its static attribute.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
---
include/linux/mm.h | 4 ++
mm/ksm.c | 112 -------------------------------------------------
mm/memory.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 124 insertions(+), 112 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index a2b4804..0fafef9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -858,6 +858,10 @@ void account_page_dirtied(struct page *page, struct address_space *mapping);
int set_page_dirty(struct page *page);
int set_page_dirty_lock(struct page *page);
int clear_page_dirty_for_io(struct page *page);
+int replace_page(struct vm_area_struct *vma, struct page *page,
+ struct page *kpage, pte_t orig_pte);
+int write_protect_page(struct vm_area_struct *vma, struct page *page,
+ pte_t *orig_pte);

extern unsigned long move_page_tables(struct vm_area_struct *vma,
unsigned long old_addr, struct vm_area_struct *new_vma,
diff --git a/mm/ksm.c b/mm/ksm.c
index 6c3e99b..ce432e1 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -713,118 +713,6 @@ static inline int pages_identical(struct page *page1, struct page *page2)
return !memcmp_pages(page1, page2);
}

-static int write_protect_page(struct vm_area_struct *vma, struct page *page,
- pte_t *orig_pte)
-{
- struct mm_struct *mm = vma->vm_mm;
- unsigned long addr;
- pte_t *ptep;
- spinlock_t *ptl;
- int swapped;
- int err = -EFAULT;
-
- addr = page_address_in_vma(page, vma);
- if (addr == -EFAULT)
- goto out;
-
- ptep = page_check_address(page, mm, addr, &ptl, 0);
- if (!ptep)
- goto out;
-
- if (pte_write(*ptep)) {
- pte_t entry;
-
- swapped = PageSwapCache(page);
- flush_cache_page(vma, addr, page_to_pfn(page));
- /*
- * Ok this is tricky, when get_user_pages_fast() run it doesnt
- * take any lock, therefore the check that we are going to make
- * with the pagecount against the mapcount is racey and
- * O_DIRECT can happen right after the check.
- * So we clear the pte and flush the tlb before the check
- * this assure us that no O_DIRECT can happen after the check
- * or in the middle of the check.
- */
- entry = ptep_clear_flush(vma, addr, ptep);
- /*
- * Check that no O_DIRECT or similar I/O is in progress on the
- * page
- */
- if (page_mapcount(page) + 1 + swapped != page_count(page)) {
- set_pte_at(mm, addr, ptep, entry);
- goto out_unlock;
- }
- entry = pte_wrprotect(entry);
- set_pte_at_notify(mm, addr, ptep, entry);
- }
- *orig_pte = *ptep;
- err = 0;
-
-out_unlock:
- pte_unmap_unlock(ptep, ptl);
-out:
- return err;
-}
-
-/**
- * replace_page - replace page in vma by new ksm page
- * @vma: vma that holds the pte pointing to page
- * @page: the page we are replacing by kpage
- * @kpage: the ksm page we replace page by
- * @orig_pte: the original value of the pte
- *
- * Returns 0 on success, -EFAULT on failure.
- */
-static int replace_page(struct vm_area_struct *vma, struct page *page,
- struct page *kpage, pte_t orig_pte)
-{
- struct mm_struct *mm = vma->vm_mm;
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *ptep;
- spinlock_t *ptl;
- unsigned long addr;
- int err = -EFAULT;
-
- addr = page_address_in_vma(page, vma);
- if (addr == -EFAULT)
- goto out;
-
- pgd = pgd_offset(mm, addr);
- if (!pgd_present(*pgd))
- goto out;
-
- pud = pud_offset(pgd, addr);
- if (!pud_present(*pud))
- goto out;
-
- pmd = pmd_offset(pud, addr);
- if (!pmd_present(*pmd))
- goto out;
-
- ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
- if (!pte_same(*ptep, orig_pte)) {
- pte_unmap_unlock(ptep, ptl);
- goto out;
- }
-
- get_page(kpage);
- page_add_anon_rmap(kpage, vma, addr);
-
- flush_cache_page(vma, addr, pte_pfn(*ptep));
- ptep_clear_flush(vma, addr, ptep);
- set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
-
- page_remove_rmap(page);
- put_page(page);
-
- pte_unmap_unlock(ptep, ptl);
- err = 0;
-out:
- return err;
-}
-
/*
* try_to_merge_one_page - take two pages and merge them into one
* @vma: the vma that holds the pte pointing to page
diff --git a/mm/memory.c b/mm/memory.c
index 119b7cc..3fb2b9d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2582,6 +2582,126 @@ void unmap_mapping_range(struct address_space *mapping,
}
EXPORT_SYMBOL(unmap_mapping_range);

+/**
+ * replace_page - replace page in vma by new ksm page
+ * @vma: vma that holds the pte pointing to page
+ * @page: the page we are replacing by kpage
+ * @kpage: the ksm page we replace page by
+ * @orig_pte: the original value of the pte
+ *
+ * Returns 0 on success, -EFAULT on failure.
+ */
+int replace_page(struct vm_area_struct *vma, struct page *page,
+ struct page *kpage, pte_t orig_pte)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *ptep;
+ spinlock_t *ptl;
+ unsigned long addr;
+ int err = -EFAULT;
+
+ addr = page_address_in_vma(page, vma);
+ if (addr == -EFAULT)
+ goto out;
+
+ pgd = pgd_offset(mm, addr);
+ if (!pgd_present(*pgd))
+ goto out;
+
+ pud = pud_offset(pgd, addr);
+ if (!pud_present(*pud))
+ goto out;
+
+ pmd = pmd_offset(pud, addr);
+ if (!pmd_present(*pmd))
+ goto out;
+
+ ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ if (!pte_same(*ptep, orig_pte)) {
+ pte_unmap_unlock(ptep, ptl);
+ goto out;
+ }
+
+ get_page(kpage);
+ page_add_anon_rmap(kpage, vma, addr);
+
+ flush_cache_page(vma, addr, pte_pfn(*ptep));
+ ptep_clear_flush(vma, addr, ptep);
+ set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
+
+ page_remove_rmap(page);
+ put_page(page);
+
+ pte_unmap_unlock(ptep, ptl);
+ err = 0;
+out:
+ return err;
+}
+
+/**
+ * write_protect_page - mark the page readonly
+ * @vma: vma that holds the page we want to mark
+ * @page: page that needs to be marked readonly
+ * @orig_pte: pte for the protected page.
+ *
+ * Returns 0 on success, -EFAULT on failure.
+ */
+int write_protect_page(struct vm_area_struct *vma, struct page *page,
+ pte_t *orig_pte)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long addr;
+ pte_t *ptep;
+ spinlock_t *ptl;
+ int swapped;
+ int err = -EFAULT;
+
+ addr = page_address_in_vma(page, vma);
+ if (addr == -EFAULT)
+ goto out;
+
+ ptep = page_check_address(page, mm, addr, &ptl, 0);
+ if (!ptep)
+ goto out;
+
+ if (pte_write(*ptep)) {
+ pte_t entry;
+
+ swapped = PageSwapCache(page);
+ flush_cache_page(vma, addr, page_to_pfn(page));
+ /*
+ * Ok this is tricky, when get_user_pages_fast() run it doesnt
+ * take any lock, therefore the check that we are going to make
+ * with the pagecount against the mapcount is racey and
+ * O_DIRECT can happen right after the check.
+ * So we clear the pte and flush the tlb before the check
+ * this assure us that no O_DIRECT can happen after the check
+ * or in the middle of the check.
+ */
+ entry = ptep_clear_flush(vma, addr, ptep);
+ /*
+ * Check that no O_DIRECT or similar I/O is in progress on the
+ * page
+ */
+ if (page_mapcount(page) + 1 + swapped != page_count(page)) {
+ set_pte_at(mm, addr, ptep, entry);
+ goto out_unlock;
+ }
+ entry = pte_wrprotect(entry);
+ set_pte_at_notify(mm, addr, ptep, entry);
+ }
+ *orig_pte = *ptep;
+ err = 0;
+
+out_unlock:
+ pte_unmap_unlock(ptep, ptl);
+out:
+ return err;
+}
+
int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
{
struct address_space *mapping = inode->i_mapping;

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