[PATCH 05/11] pagemap: redefine callback functions for page table walker

[Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>]

pagemap_pte_range() connected to pmd_entry() does both of pmd loop and
pte loop. So this patch moves pte part into pagemap_pte() on pte_entry().

We remove VM_SOFTDIRTY check in pagemap_pte_range(), because in the new
page table walker we call __walk_page_range() for each vma separately,
so we never experience multiple vmas in single pgd/pud/pmd/pte loop.

Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
 fs/proc/task_mmu.c | 71 +++++++++++++++++++++---------------------------------
 1 file changed, 27 insertions(+), 44 deletions(-)

diff --git v3.12-rc4.orig/fs/proc/task_mmu.c v3.12-rc4/fs/proc/task_mmu.c
index 4abe883..21e5828 100644
--- v3.12-rc4.orig/fs/proc/task_mmu.c
+++ v3.12-rc4/fs/proc/task_mmu.c
@@ -961,18 +961,32 @@ static inline void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemap
 }
 #endif
 
-static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
+static int pagemap_pte(pte_t *pte, unsigned long addr, unsigned long end,
 			     struct mm_walk *walk)
 {
-	struct vm_area_struct *vma;
+	struct vm_area_struct *vma = walk->vma;
 	struct pagemapread *pm = walk->private;
-	pte_t *pte;
+	pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
+
+	if (vma && vma->vm_start <= addr && end <= vma->vm_end) {
+		pte_to_pagemap_entry(&pme, pm, vma, addr, *pte);
+		/* unmap before userspace copy */
+		pte_unmap(pte);
+	}
+	return add_to_pagemap(addr, &pme, pm);
+}
+
+static int pagemap_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,
+			     struct mm_walk *walk)
+{
 	int err = 0;
+	struct vm_area_struct *vma = walk->vma;
+	struct pagemapread *pm = walk->private;
 	pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
 
-	/* find the first VMA at or above 'addr' */
-	vma = find_vma(walk->mm, addr);
-	if (vma && pmd_trans_huge_lock(pmd, vma) == 1) {
+	if (!vma)
+		return err;
+	if (pmd_trans_huge_lock(pmd, vma) == 1) {
 		int pmd_flags2;
 
 		if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(*pmd))
@@ -991,41 +1005,9 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 				break;
 		}
 		spin_unlock(&walk->mm->page_table_lock);
-		return err;
-	}
-
-	if (pmd_trans_unstable(pmd))
-		return 0;
-	for (; addr != end; addr += PAGE_SIZE) {
-		int flags2;
-
-		/* check to see if we've left 'vma' behind
-		 * and need a new, higher one */
-		if (vma && (addr >= vma->vm_end)) {
-			vma = find_vma(walk->mm, addr);
-			if (vma && (vma->vm_flags & VM_SOFTDIRTY))
-				flags2 = __PM_SOFT_DIRTY;
-			else
-				flags2 = 0;
-			pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, flags2));
-		}
-
-		/* check that 'vma' actually covers this address,
-		 * and that it isn't a huge page vma */
-		if (vma && (vma->vm_start <= addr) &&
-		    !is_vm_hugetlb_page(vma)) {
-			pte = pte_offset_map(pmd, addr);
-			pte_to_pagemap_entry(&pme, pm, vma, addr, *pte);
-			/* unmap before userspace copy */
-			pte_unmap(pte);
-		}
-		err = add_to_pagemap(addr, &pme, pm);
-		if (err)
-			return err;
+		/* don't call pagemap_pte() */
+		walk->skip = 1;
 	}
-
-	cond_resched();
-
 	return err;
 }
 
@@ -1048,12 +1030,11 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 				 struct mm_walk *walk)
 {
 	struct pagemapread *pm = walk->private;
-	struct vm_area_struct *vma;
+	struct vm_area_struct *vma = walk->vma;
 	int err = 0;
 	int flags2;
 	pagemap_entry_t pme;
 
-	vma = find_vma(walk->mm, addr);
 	WARN_ON_ONCE(!vma);
 
 	if (vma && (vma->vm_flags & VM_SOFTDIRTY))
@@ -1061,6 +1042,7 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 	else
 		flags2 = 0;
 
+	hmask = huge_page_mask(hstate_vma(vma));
 	for (; addr != end; addr += PAGE_SIZE) {
 		int offset = (addr & ~hmask) >> PAGE_SHIFT;
 		huge_pte_to_pagemap_entry(&pme, pm, *pte, offset, flags2);
@@ -1137,10 +1119,11 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
 	if (!mm || IS_ERR(mm))
 		goto out_free;
 
-	pagemap_walk.pmd_entry = pagemap_pte_range;
+	pagemap_walk.pte_entry = pagemap_pte;
+	pagemap_walk.pmd_entry = pagemap_pmd;
 	pagemap_walk.pte_hole = pagemap_pte_hole;
 #ifdef CONFIG_HUGETLB_PAGE
-	pagemap_walk.hugetlb_entry = pagemap_hugetlb_range;
+	pagemap_walk.hugetlb_entry = pagemap_hugetlb;
 #endif
 	pagemap_walk.mm = mm;
 	pagemap_walk.private = &pm;
-- 
1.8.3.1

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