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Subject[PATCH v4 13/13] mincore: apply page table walker on do_mincore()
Date
This patch makes do_mincore() use walk_page_vma(), which reduces many lines
of code by using common page table walk code.

ChangeLog v4:
- remove redundant vma

ChangeLog v3:
- add NULL vma check in mincore_unmapped_range()
- don't use pte_entry()

ChangeLog v2:
- change type of args of callbacks to void *
- move definition of mincore_walk to the start of the function to fix compiler
warning

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
mm/huge_memory.c | 20 -------
mm/mincore.c | 173 ++++++++++++++++++++-----------------------------------
2 files changed, 62 insertions(+), 131 deletions(-)

diff --git v3.16-rc3.orig/mm/huge_memory.c v3.16-rc3/mm/huge_memory.c
index 33514d88fef9..63bed13c6cf5 100644
--- v3.16-rc3.orig/mm/huge_memory.c
+++ v3.16-rc3/mm/huge_memory.c
@@ -1410,26 +1410,6 @@ 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 v3.16-rc3.orig/mm/mincore.c v3.16-rc3/mm/mincore.c
index 725c80961048..3c64dcbcb3e2 100644
--- v3.16-rc3.orig/mm/mincore.c
+++ v3.16-rc3/mm/mincore.c
@@ -19,38 +19,26 @@
#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)
{
+ int err = 0;
#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 += (end - addr) >> PAGE_SHIFT;
#else
BUG();
#endif
+ return err;
}

/*
@@ -94,14 +82,15 @@ 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 mm_walk *walk)
{
+ struct vm_area_struct *vma = walk->vma;
+ unsigned char *vec = walk->private;
unsigned long nr = (end - addr) >> PAGE_SHIFT;
int i;

- if (vma->vm_file) {
+ if (vma && vma->vm_file) {
pgoff_t pgoff;

pgoff = linear_page_index(vma, addr);
@@ -111,25 +100,38 @@ static void mincore_unmapped_range(struct vm_area_struct *vma,
for (i = 0; i < nr; i++)
vec[i] = 0;
}
+ walk->private += nr;
+ 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;

- ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- do {
+ if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
+ memset(walk->private, 1, (end - addr) >> PAGE_SHIFT);
+ walk->private += (end - addr) >> PAGE_SHIFT;
+ spin_unlock(ptl);
+ return 0;
+ }
+
+ if (pmd_trans_unstable(pmd))
+ return 0;
+
+ ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ for (; addr != end; ptep++, addr += PAGE_SIZE) {
pte_t pte = *ptep;
pgoff_t pgoff;
+ unsigned char *vec = walk->private;

- next = addr + PAGE_SIZE;
- if (pte_none(pte))
- mincore_unmapped_range(vma, addr, next, vec);
- else if (pte_present(pte))
+ if (pte_none(pte)) {
+ mincore_unmapped_range(addr, addr + PAGE_SIZE, walk);
+ continue;
+ }
+ if (pte_present(pte))
*vec = 1;
else if (pte_file(pte)) {
pgoff = pte_to_pgoff(pte);
@@ -151,70 +153,11 @@ static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
#endif
}
}
- vec++;
- } while (ptep++, addr = next, addr != end);
+ walk->private++;
+ }
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);
+ cond_resched();
+ return 0;
}

/*
@@ -225,20 +168,28 @@ static void mincore_page_range(struct vm_area_struct *vma,
static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
{
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_vma(vma, &mincore_walk);
+ if (err < 0)
+ return err;
+ else {
+ unsigned long end;

- return (end - addr) >> PAGE_SHIFT;
+ end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
+ return (end - addr) >> PAGE_SHIFT;
+ }
}

/*
--
1.9.3


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