mincore: apply page table walker on do_mincore()

This patch makes do_mincore() use walk_page_vma(), which reduces many
lines of code by using common page table walk code.

[daeseok.youn@gmail.com: remove unneeded variable 'err']
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 60 insertions, 126 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 0531ea7dd7cf..29bc6e471df4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1412,26 +1412,6 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
         return ret;
 }
 
-int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
-                unsigned long addr, unsigned long end,
-                unsigned char *vec)
-{
-        spinlock_t *ptl;
-        int ret = 0;
-
-        if (__pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
-                /*
-                 * All logical pages in the range are present
-                 * if backed by a huge page.
-                 */
-                spin_unlock(ptl);
-                memset(vec, 1, (end - addr) >> PAGE_SHIFT);
-                ret = 1;
-        }
-
-        return ret;
-}
-
 int move_huge_pmd(struct vm_area_struct *vma, struct vm_area_struct *new_vma,
                   unsigned long old_addr,
                   unsigned long new_addr, unsigned long old_end,
diff --git a/mm/mincore.c b/mm/mincore.c
index 46527c023e0c..be25efde64a4 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -19,38 +19,25 @@
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 
-static void mincore_hugetlb_page_range(struct vm_area_struct *vma,
-                                unsigned long addr, unsigned long end,
-                                unsigned char *vec)
+static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
+                        unsigned long end, struct mm_walk *walk)
 {
 #ifdef CONFIG_HUGETLB_PAGE
-        struct hstate *h;
+        unsigned char present;
+        unsigned char *vec = walk->private;
 
-        h = hstate_vma(vma);
-        while (1) {
-                unsigned char present;
-                pte_t *ptep;
-                /*
-                 * Huge pages are always in RAM for now, but
-                 * theoretically it needs to be checked.
-                 */
-                ptep = huge_pte_offset(current->mm,
-                                       addr & huge_page_mask(h));
-                present = ptep && !huge_pte_none(huge_ptep_get(ptep));
-                while (1) {
-                        *vec = present;
-                        vec++;
-                        addr += PAGE_SIZE;
-                        if (addr == end)
-                                return;
-                        /* check hugepage border */
-                        if (!(addr & ~huge_page_mask(h)))
-                                break;
-                }
-        }
+        /*
+         * Hugepages under user process are always in RAM and never
+         * swapped out, but theoretically it needs to be checked.
+         */
+        present = pte && !huge_pte_none(huge_ptep_get(pte));
+        for (; addr != end; vec++, addr += PAGE_SIZE)
+                *vec = present;
+        walk->private = vec;
 #else
         BUG();
 #endif
+        return 0;
 }
 
 /*
@@ -94,9 +81,8 @@ static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
         return present;
 }
 
-static void mincore_unmapped_range(struct vm_area_struct *vma,
-                                unsigned long addr, unsigned long end,
-                                unsigned char *vec)
+static int __mincore_unmapped_range(unsigned long addr, unsigned long end,
+                                struct vm_area_struct *vma, unsigned char *vec)
 {
         unsigned long nr = (end - addr) >> PAGE_SHIFT;
         int i;
@@ -111,23 +97,44 @@ static void mincore_unmapped_range(struct vm_area_struct *vma,
                 for (i = 0; i < nr; i++)
                         vec[i] = 0;
         }
+        return nr;
+}
+
+static int mincore_unmapped_range(unsigned long addr, unsigned long end,
+                                   struct mm_walk *walk)
+{
+        walk->private += __mincore_unmapped_range(addr, end,
+                                                  walk->vma, walk->private);
+        return 0;
 }
 
-static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
-                        unsigned long addr, unsigned long end,
-                        unsigned char *vec)
+static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
+                        struct mm_walk *walk)
 {
-        unsigned long next;
         spinlock_t *ptl;
+        struct vm_area_struct *vma = walk->vma;
         pte_t *ptep;
+        unsigned char *vec = walk->private;
+        int nr = (end - addr) >> PAGE_SHIFT;
+
+        if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+                memset(vec, 1, nr);
+                spin_unlock(ptl);
+                goto out;
+        }
+
+        if (pmd_trans_unstable(pmd)) {
+                __mincore_unmapped_range(addr, end, vma, vec);
+                goto out;
+        }
 
-        ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
-        do {
+        ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+        for (; addr != end; ptep++, addr += PAGE_SIZE) {
                 pte_t pte = *ptep;
 
-                next = addr + PAGE_SIZE;
                 if (pte_none(pte))
-                        mincore_unmapped_range(vma, addr, next, vec);
+                        __mincore_unmapped_range(addr, addr + PAGE_SIZE,
+                                                 vma, vec);
                 else if (pte_present(pte))
                         *vec = 1;
                 else { /* pte is a swap entry */
@@ -150,69 +157,12 @@ static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
                         }
                 }
                 vec++;
-        } while (ptep++, addr = next, addr != end);
+        }
         pte_unmap_unlock(ptep - 1, ptl);
-}
-
-static void mincore_pmd_range(struct vm_area_struct *vma, pud_t *pud,
-                        unsigned long addr, unsigned long end,
-                        unsigned char *vec)
-{
-        unsigned long next;
-        pmd_t *pmd;
-
-        pmd = pmd_offset(pud, addr);
-        do {
-                next = pmd_addr_end(addr, end);
-                if (pmd_trans_huge(*pmd)) {
-                        if (mincore_huge_pmd(vma, pmd, addr, next, vec)) {
-                                vec += (next - addr) >> PAGE_SHIFT;
-                                continue;
-                        }
-                        /* fall through */
-                }
-                if (pmd_none_or_trans_huge_or_clear_bad(pmd))
-                        mincore_unmapped_range(vma, addr, next, vec);
-                else
-                        mincore_pte_range(vma, pmd, addr, next, vec);
-                vec += (next - addr) >> PAGE_SHIFT;
-        } while (pmd++, addr = next, addr != end);
-}
-
-static void mincore_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
-                        unsigned long addr, unsigned long end,
-                        unsigned char *vec)
-{
-        unsigned long next;
-        pud_t *pud;
-
-        pud = pud_offset(pgd, addr);
-        do {
-                next = pud_addr_end(addr, end);
-                if (pud_none_or_clear_bad(pud))
-                        mincore_unmapped_range(vma, addr, next, vec);
-                else
-                        mincore_pmd_range(vma, pud, addr, next, vec);
-                vec += (next - addr) >> PAGE_SHIFT;
-        } while (pud++, addr = next, addr != end);
-}
-
-static void mincore_page_range(struct vm_area_struct *vma,
-                        unsigned long addr, unsigned long end,
-                        unsigned char *vec)
-{
-        unsigned long next;
-        pgd_t *pgd;
-
-        pgd = pgd_offset(vma->vm_mm, addr);
-        do {
-                next = pgd_addr_end(addr, end);
-                if (pgd_none_or_clear_bad(pgd))
-                        mincore_unmapped_range(vma, addr, next, vec);
-                else
-                        mincore_pud_range(vma, pgd, addr, next, vec);
-                vec += (next - addr) >> PAGE_SHIFT;
-        } while (pgd++, addr = next, addr != end);
+out:
+        walk->private += nr;
+        cond_resched();
+        return 0;
 }
 
 /*
@@ -224,18 +174,22 @@ 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)
                 return -ENOMEM;
-
+        mincore_walk.mm = vma->vm_mm;
         end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
-
-        if (is_vm_hugetlb_page(vma))
-                mincore_hugetlb_page_range(vma, addr, end, vec);
-        else
-                mincore_page_range(vma, addr, end, vec);
-
+        err = walk_page_range(addr, end, &mincore_walk);
+        if (err < 0)
+                return err;
         return (end - addr) >> PAGE_SHIFT;
 }