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authorMel Gorman <mgorman@suse.de>2012-10-25 14:16:32 +0200
committerMel Gorman <mgorman@suse.de>2012-12-11 14:42:44 +0000
commit4b10e7d562c90d0a72f324832c26653947a07381 (patch)
tree733e0fc3ac3fdfe27a312bc72e4ffb07bbf0aa56 /mm/mempolicy.c
parentb24f53a0bea38b266d219ee651b22dba727c44ae (diff)
downloadlinux-4b10e7d562c90d0a72f324832c26653947a07381.tar.gz
mm: mempolicy: Implement change_prot_numa() in terms of change_protection()
This patch converts change_prot_numa() to use change_protection(). As pte_numa and friends check the PTE bits directly it is necessary for change_protection() to use pmd_mknuma(). Hence the required modifications to change_protection() are a little clumsy but the end result is that most of the numa page table helpers are just one or two instructions. Signed-off-by: Mel Gorman <mgorman@suse.de>
Diffstat (limited to 'mm/mempolicy.c')
-rw-r--r--mm/mempolicy.c137
1 files changed, 13 insertions, 124 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 51d3ebd8561..75d4600a5e9 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -568,134 +568,23 @@ static inline int check_pgd_range(struct vm_area_struct *vma,
#ifdef CONFIG_ARCH_USES_NUMA_PROT_NONE
/*
- * Here we search for not shared page mappings (mapcount == 1) and we
- * set up the pmd/pte_numa on those mappings so the very next access
- * will fire a NUMA hinting page fault.
+ * This is used to mark a range of virtual addresses to be inaccessible.
+ * These are later cleared by a NUMA hinting fault. Depending on these
+ * faults, pages may be migrated for better NUMA placement.
+ *
+ * This is assuming that NUMA faults are handled using PROT_NONE. If
+ * an architecture makes a different choice, it will need further
+ * changes to the core.
*/
-static int
-change_prot_numa_range(struct mm_struct *mm, struct vm_area_struct *vma,
- unsigned long address)
-{
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *pte, *_pte;
- struct page *page;
- unsigned long _address, end;
- spinlock_t *ptl;
- int ret = 0;
-
- VM_BUG_ON(address & ~PAGE_MASK);
-
- pgd = pgd_offset(mm, address);
- if (!pgd_present(*pgd))
- goto out;
-
- pud = pud_offset(pgd, address);
- if (!pud_present(*pud))
- goto out;
-
- pmd = pmd_offset(pud, address);
- if (pmd_none(*pmd))
- goto out;
-
- if (pmd_trans_huge_lock(pmd, vma) == 1) {
- int page_nid;
- ret = HPAGE_PMD_NR;
-
- VM_BUG_ON(address & ~HPAGE_PMD_MASK);
-
- if (pmd_numa(*pmd)) {
- spin_unlock(&mm->page_table_lock);
- goto out;
- }
-
- page = pmd_page(*pmd);
-
- /* only check non-shared pages */
- if (page_mapcount(page) != 1) {
- spin_unlock(&mm->page_table_lock);
- goto out;
- }
-
- page_nid = page_to_nid(page);
-
- if (pmd_numa(*pmd)) {
- spin_unlock(&mm->page_table_lock);
- goto out;
- }
-
- set_pmd_at(mm, address, pmd, pmd_mknuma(*pmd));
- ret += HPAGE_PMD_NR;
- /* defer TLB flush to lower the overhead */
- spin_unlock(&mm->page_table_lock);
- goto out;
- }
-
- if (pmd_trans_unstable(pmd))
- goto out;
- VM_BUG_ON(!pmd_present(*pmd));
-
- end = min(vma->vm_end, (address + PMD_SIZE) & PMD_MASK);
- pte = pte_offset_map_lock(mm, pmd, address, &ptl);
- for (_address = address, _pte = pte; _address < end;
- _pte++, _address += PAGE_SIZE) {
- pte_t pteval = *_pte;
- if (!pte_present(pteval))
- continue;
- if (pte_numa(pteval))
- continue;
- page = vm_normal_page(vma, _address, pteval);
- if (unlikely(!page))
- continue;
- /* only check non-shared pages */
- if (page_mapcount(page) != 1)
- continue;
-
- set_pte_at(mm, _address, _pte, pte_mknuma(pteval));
-
- /* defer TLB flush to lower the overhead */
- ret++;
- }
- pte_unmap_unlock(pte, ptl);
-
- if (ret && !pmd_numa(*pmd)) {
- spin_lock(&mm->page_table_lock);
- set_pmd_at(mm, address, pmd, pmd_mknuma(*pmd));
- spin_unlock(&mm->page_table_lock);
- /* defer TLB flush to lower the overhead */
- }
-
-out:
- return ret;
-}
-
-/* Assumes mmap_sem is held */
-void
-change_prot_numa(struct vm_area_struct *vma,
- unsigned long address, unsigned long end)
+unsigned long change_prot_numa(struct vm_area_struct *vma,
+ unsigned long addr, unsigned long end)
{
- struct mm_struct *mm = vma->vm_mm;
- int progress = 0;
-
- while (address < end) {
- VM_BUG_ON(address < vma->vm_start ||
- address + PAGE_SIZE > vma->vm_end);
+ int nr_updated;
+ BUILD_BUG_ON(_PAGE_NUMA != _PAGE_PROTNONE);
- progress += change_prot_numa_range(mm, vma, address);
- address = (address + PMD_SIZE) & PMD_MASK;
- }
+ nr_updated = change_protection(vma, addr, end, vma->vm_page_prot, 0, 1);
- /*
- * Flush the TLB for the mm to start the NUMA hinting
- * page faults after we finish scanning this vma part
- * if there were any PTE updates
- */
- if (progress) {
- mmu_notifier_invalidate_range_start(vma->vm_mm, address, end);
- flush_tlb_range(vma, address, end);
- mmu_notifier_invalidate_range_end(vma->vm_mm, address, end);
- }
+ return nr_updated;
}
#else
static unsigned long change_prot_numa(struct vm_area_struct *vma,