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Subject[PATCH v4 11/13] mempolicy: apply page table walker on queue_pages_range()
Date
queue_pages_range() does page table walking in its own way now, but there
is some code duplicate. This patch applies page table walker to reduce
lines of code.

queue_pages_range() has to do some precheck to determine whether we really
walk over the vma or just skip it. Now we have test_walk() callback in
mm_walk for this purpose, so we can do this replacement cleanly.
queue_pages_test_walk() depends on not only the current vma but also the
previous one, so queue_pages->prev is introduced to remember it.

ChangeLog v4:
- rebase to v3.16-rc3, where the return value of queue_pages_range()
becomes 0 in success instead of the first found vma, and use -EFAILT
instead of ERR_PTR() in failure.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
mm/mempolicy.c | 224 +++++++++++++++++++++++----------------------------------
1 file changed, 90 insertions(+), 134 deletions(-)

diff --git v3.16-rc3.orig/mm/mempolicy.c v3.16-rc3/mm/mempolicy.c
index eb58de19f815..47a6fa913b83 100644
--- v3.16-rc3.orig/mm/mempolicy.c
+++ v3.16-rc3/mm/mempolicy.c
@@ -479,24 +479,34 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
static void migrate_page_add(struct page *page, struct list_head *pagelist,
unsigned long flags);

+struct queue_pages {
+ struct list_head *pagelist;
+ unsigned long flags;
+ nodemask_t *nmask;
+ struct vm_area_struct *prev;
+};
+
/*
* Scan through pages checking if pages follow certain conditions,
* and move them to the pagelist if they do.
*/
-static int queue_pages_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
- unsigned long addr, unsigned long end,
- const nodemask_t *nodes, unsigned long flags,
- void *private)
+static int queue_pages_pte_range(pmd_t *pmd, unsigned long addr,
+ unsigned long end, struct mm_walk *walk)
{
- pte_t *orig_pte;
+ struct vm_area_struct *vma = walk->vma;
+ struct page *page;
+ struct queue_pages *qp = walk->private;
+ unsigned long flags = qp->flags;
+ int nid;
pte_t *pte;
spinlock_t *ptl;

- orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- do {
- struct page *page;
- int nid;
+ split_huge_page_pmd(vma, addr, pmd);
+ if (pmd_trans_unstable(pmd))
+ return 0;

+ pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+ for (; addr != end; pte++, addr += PAGE_SIZE) {
if (!pte_present(*pte))
continue;
page = vm_normal_page(vma, addr, *pte);
@@ -509,114 +519,46 @@ static int queue_pages_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
if (PageReserved(page))
continue;
nid = page_to_nid(page);
- if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
+ if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
continue;

if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
- migrate_page_add(page, private, flags);
- else
- break;
- } while (pte++, addr += PAGE_SIZE, addr != end);
- pte_unmap_unlock(orig_pte, ptl);
- return addr != end;
+ migrate_page_add(page, qp->pagelist, flags);
+ }
+ pte_unmap_unlock(pte - 1, ptl);
+ cond_resched();
+ return 0;
}

-static void queue_pages_hugetlb_pmd_range(struct vm_area_struct *vma,
- pmd_t *pmd, const nodemask_t *nodes, unsigned long flags,
- void *private)
+static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
+ unsigned long addr, unsigned long end,
+ struct mm_walk *walk)
{
#ifdef CONFIG_HUGETLB_PAGE
+ struct queue_pages *qp = walk->private;
+ unsigned long flags = qp->flags;
int nid;
struct page *page;
spinlock_t *ptl;
pte_t entry;

- ptl = huge_pte_lock(hstate_vma(vma), vma->vm_mm, (pte_t *)pmd);
- entry = huge_ptep_get((pte_t *)pmd);
+ ptl = huge_pte_lock(hstate_vma(walk->vma), walk->mm, pte);
+ entry = huge_ptep_get(pte);
if (!pte_present(entry))
goto unlock;
page = pte_page(entry);
nid = page_to_nid(page);
- if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
+ if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
goto unlock;
/* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
if (flags & (MPOL_MF_MOVE_ALL) ||
(flags & MPOL_MF_MOVE && page_mapcount(page) == 1))
- isolate_huge_page(page, private);
+ isolate_huge_page(page, qp->pagelist);
unlock:
spin_unlock(ptl);
#else
BUG();
#endif
-}
-
-static inline int queue_pages_pmd_range(struct vm_area_struct *vma, pud_t *pud,
- unsigned long addr, unsigned long end,
- const nodemask_t *nodes, unsigned long flags,
- void *private)
-{
- pmd_t *pmd;
- unsigned long next;
-
- pmd = pmd_offset(pud, addr);
- do {
- next = pmd_addr_end(addr, end);
- if (!pmd_present(*pmd))
- continue;
- if (pmd_huge(*pmd) && is_vm_hugetlb_page(vma)) {
- queue_pages_hugetlb_pmd_range(vma, pmd, nodes,
- flags, private);
- continue;
- }
- split_huge_page_pmd(vma, addr, pmd);
- if (pmd_none_or_trans_huge_or_clear_bad(pmd))
- continue;
- if (queue_pages_pte_range(vma, pmd, addr, next, nodes,
- flags, private))
- return -EIO;
- } while (pmd++, addr = next, addr != end);
- return 0;
-}
-
-static inline int queue_pages_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
- unsigned long addr, unsigned long end,
- const nodemask_t *nodes, unsigned long flags,
- void *private)
-{
- pud_t *pud;
- unsigned long next;
-
- pud = pud_offset(pgd, addr);
- do {
- next = pud_addr_end(addr, end);
- if (pud_huge(*pud) && is_vm_hugetlb_page(vma))
- continue;
- if (pud_none_or_clear_bad(pud))
- continue;
- if (queue_pages_pmd_range(vma, pud, addr, next, nodes,
- flags, private))
- return -EIO;
- } while (pud++, addr = next, addr != end);
- return 0;
-}
-
-static inline int queue_pages_pgd_range(struct vm_area_struct *vma,
- unsigned long addr, unsigned long end,
- const nodemask_t *nodes, unsigned long flags,
- void *private)
-{
- pgd_t *pgd;
- unsigned long next;
-
- pgd = pgd_offset(vma->vm_mm, addr);
- do {
- next = pgd_addr_end(addr, end);
- if (pgd_none_or_clear_bad(pgd))
- continue;
- if (queue_pages_pud_range(vma, pgd, addr, next, nodes,
- flags, private))
- return -EIO;
- } while (pgd++, addr = next, addr != end);
return 0;
}

@@ -649,6 +591,44 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma,
}
#endif /* CONFIG_NUMA_BALANCING */

+static int queue_pages_test_walk(unsigned long start, unsigned long end,
+ struct mm_walk *walk)
+{
+ struct vm_area_struct *vma = walk->vma;
+ struct queue_pages *qp = walk->private;
+ unsigned long endvma = vma->vm_end;
+ unsigned long flags = qp->flags;
+
+ if (endvma > end)
+ endvma = end;
+ if (vma->vm_start > start)
+ start = vma->vm_start;
+
+ if (!(flags & MPOL_MF_DISCONTIG_OK)) {
+ if (!vma->vm_next && vma->vm_end < end)
+ return -EFAULT;
+ if (qp->prev && qp->prev->vm_end < vma->vm_start)
+ return -EFAULT;
+ }
+
+ qp->prev = vma;
+
+ if (vma->vm_flags & VM_PFNMAP)
+ return 1;
+
+ if (flags & MPOL_MF_LAZY) {
+ change_prot_numa(vma, start, endvma);
+ return 1;
+ }
+
+ if ((flags & MPOL_MF_STRICT) ||
+ ((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
+ vma_migratable(vma)))
+ /* queue pages from current vma */
+ return 0;
+ return 1;
+}
+
/*
* Walk through page tables and collect pages to be migrated.
*
@@ -658,48 +638,24 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma,
*/
static int
queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
- const nodemask_t *nodes, unsigned long flags, void *private)
-{
- int err = 0;
- struct vm_area_struct *vma, *prev;
-
- vma = find_vma(mm, start);
- if (!vma)
- return -EFAULT;
- prev = NULL;
- for (; vma && vma->vm_start < end; vma = vma->vm_next) {
- unsigned long endvma = vma->vm_end;
-
- if (endvma > end)
- endvma = end;
- if (vma->vm_start > start)
- start = vma->vm_start;
-
- if (!(flags & MPOL_MF_DISCONTIG_OK)) {
- if (!vma->vm_next && vma->vm_end < end)
- return -EFAULT;
- if (prev && prev->vm_end < vma->vm_start)
- return -EFAULT;
- }
-
- if (flags & MPOL_MF_LAZY) {
- change_prot_numa(vma, start, endvma);
- goto next;
- }
-
- if ((flags & MPOL_MF_STRICT) ||
- ((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
- vma_migratable(vma))) {
-
- err = queue_pages_pgd_range(vma, start, endvma, nodes,
- flags, private);
- if (err)
- break;
- }
-next:
- prev = vma;
- }
- return err;
+ nodemask_t *nodes, unsigned long flags,
+ struct list_head *pagelist)
+{
+ struct queue_pages qp = {
+ .pagelist = pagelist,
+ .flags = flags,
+ .nmask = nodes,
+ .prev = NULL,
+ };
+ struct mm_walk queue_pages_walk = {
+ .hugetlb_entry = queue_pages_hugetlb,
+ .pmd_entry = queue_pages_pte_range,
+ .test_walk = queue_pages_test_walk,
+ .mm = mm,
+ .private = &qp,
+ };
+
+ return walk_page_range(start, end, &queue_pages_walk);
}

/*
--
1.9.3


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