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Subject[PATCH 11/11] mempolicy: apply page table walker on queue_pages_range()
Date
queue_pages_range() does page table walking in its own way now,
so this patch rewrites it with walk_page_range().
One difficulty was that queue_pages_range() needed to check vmas
to determine whether we queue pages from a given vma or skip it.
Now we have test_walk() callback in mm_walk for that purpose,
so we can do the replacement cleanly. queue_pages_test_walk()
depends on not only the current vma but also the previous one,
so we use queue_pages->prev to keep it.

ChangeLog v2:
- rebase onto mmots
- add VM_PFNMAP check on queue_pages_test_walk()

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
mm/mempolicy.c | 255 ++++++++++++++++++++++-----------------------------------
1 file changed, 99 insertions(+), 156 deletions(-)

diff --git v3.12-rc7-mmots-2013-10-29-16-24.orig/mm/mempolicy.c v3.12-rc7-mmots-2013-10-29-16-24/mm/mempolicy.c
index f8f9790..913df80 100644
--- v3.12-rc7-mmots-2013-10-29-16-24.orig/mm/mempolicy.c
+++ v3.12-rc7-mmots-2013-10-29-16-24/mm/mempolicy.c
@@ -476,140 +476,66 @@ 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(pte_t *pte, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
{
- pte_t *orig_pte;
- 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;
+ struct vm_area_struct *vma = walk->vma;
+ struct page *page;
+ struct queue_pages *qp = walk->private;
+ unsigned long flags = qp->flags;
+ int nid;

- if (!pte_present(*pte))
- continue;
- page = vm_normal_page(vma, addr, *pte);
- if (!page)
- continue;
- /*
- * vm_normal_page() filters out zero pages, but there might
- * still be PageReserved pages to skip, perhaps in a VDSO.
- */
- if (PageReserved(page))
- continue;
- nid = page_to_nid(page);
- if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
- continue;
+ if (!pte_present(*pte))
+ return 0;
+ page = vm_normal_page(vma, addr, *pte);
+ if (!page)
+ return 0;
+ /*
+ * vm_normal_page() filters out zero pages, but there might
+ * still be PageReserved pages to skip, perhaps in a VDSO.
+ */
+ if (PageReserved(page))
+ return 0;
+ nid = page_to_nid(page);
+ if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
+ return 0;

- 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;
+ if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
+ migrate_page_add(page, qp->pagelist, flags);
+ 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 addr,
+ unsigned long next, 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;

- ptl = huge_pte_lock(hstate_vma(vma), vma->vm_mm, (pte_t *)pmd);
- page = pte_page(huge_ptep_get((pte_t *)pmd));
+ page = pte_page(huge_ptep_get(pte));
nid = page_to_nid(page);
- if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
- goto unlock;
+ if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
+ return 0;
/* 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);
-unlock:
- spin_unlock(ptl);
+ isolate_huge_page(page, qp->pagelist);
#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;
}

@@ -643,6 +569,45 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma,
}
#endif /* CONFIG_ARCH_USES_NUMA_PROT_NONE */

+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;
+ walk->skip = 1;
+
+ if (vma->vm_flags & VM_PFNMAP)
+ return 0;
+
+ if (flags & MPOL_MF_LAZY) {
+ change_prot_numa(vma, start, endvma);
+ return 0;
+ }
+
+ if ((flags & MPOL_MF_STRICT) ||
+ ((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
+ vma_migratable(vma)))
+ /* queue pages from current vma */
+ walk->skip = 0;
+ return 0;
+}
+
/*
* Walk through page tables and collect pages to be migrated.
*
@@ -652,51 +617,29 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma,
*/
static struct vm_area_struct *
queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
- const nodemask_t *nodes, unsigned long flags, void *private)
+ nodemask_t *nodes, unsigned long flags,
+ struct list_head *pagelist)
{
int err;
- struct vm_area_struct *first, *vma, *prev;
-
-
- first = find_vma(mm, start);
- if (!first)
- return ERR_PTR(-EFAULT);
- prev = NULL;
- for (vma = first; 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 ERR_PTR(-EFAULT);
- if (prev && prev->vm_end < vma->vm_start)
- return ERR_PTR(-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) {
- first = ERR_PTR(err);
- break;
- }
- }
-next:
- prev = vma;
- }
- return first;
+ struct queue_pages qp = {
+ .pagelist = pagelist,
+ .flags = flags,
+ .nmask = nodes,
+ .prev = NULL,
+ };
+ struct mm_walk queue_pages_walk = {
+ .hugetlb_entry = queue_pages_hugetlb,
+ .pte_entry = queue_pages_pte,
+ .test_walk = queue_pages_test_walk,
+ .mm = mm,
+ .private = &qp,
+ };
+
+ err = walk_page_range(start, end, &queue_pages_walk);
+ if (err < 0)
+ return ERR_PTR(err);
+ else
+ return find_vma(mm, start);
}

/*
--
1.8.3.1


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