#include <linux/backing-dev.h>
#include <linux/swap.h>
#include <linux/swapops.h>
+#include <linux/mmu_notifier.h>
+
+#include <asm/tlb.h>
/*
* Any behaviour which results in changes to the vma->vm_flags needs to
case MADV_REMOVE:
case MADV_WILLNEED:
case MADV_DONTNEED:
+ case MADV_FREE:
return 0;
default:
/* be safe, default to 1. list exceptions explicitly */
return 0;
}
+static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
+ unsigned long end, struct mm_walk *walk)
+
+{
+ struct mmu_gather *tlb = walk->private;
+ struct mm_struct *mm = tlb->mm;
+ struct vm_area_struct *vma = walk->vma;
+ spinlock_t *ptl;
+ pte_t *pte, ptent;
+ struct page *page;
+ swp_entry_t entry;
+ unsigned long next;
+ int nr_swap = 0;
+
+ next = pmd_addr_end(addr, end);
+ if (pmd_trans_huge(*pmd)) {
+ if (next - addr != HPAGE_PMD_SIZE)
+ split_huge_pmd(vma, pmd, addr);
+ else if (!madvise_free_huge_pmd(tlb, vma, pmd, addr))
+ goto next;
+ /* fall through */
+ }
+
+ if (pmd_trans_unstable(pmd))
+ return 0;
+
+ pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ arch_enter_lazy_mmu_mode();
+ for (; addr != end; pte++, addr += PAGE_SIZE) {
+ ptent = *pte;
+
+ if (pte_none(ptent))
+ continue;
+ /*
+ * If the pte has swp_entry, just clear page table to
+ * prevent swap-in which is more expensive rather than
+ * (page allocation + zeroing).
+ */
+ if (!pte_present(ptent)) {
+ entry = pte_to_swp_entry(ptent);
+ if (non_swap_entry(entry))
+ continue;
+ nr_swap--;
+ free_swap_and_cache(entry);
+ pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
+ continue;
+ }
+
+ page = vm_normal_page(vma, addr, ptent);
+ if (!page)
+ continue;
+
+ if (PageSwapCache(page) || PageDirty(page)) {
+ if (!trylock_page(page))
+ continue;
+ /*
+ * If page is shared with others, we couldn't clear
+ * PG_dirty of the page.
+ */
+ if (page_count(page) != 1 + !!PageSwapCache(page)) {
+ unlock_page(page);
+ continue;
+ }
+
+ if (PageSwapCache(page) && !try_to_free_swap(page)) {
+ unlock_page(page);
+ continue;
+ }
+
+ ClearPageDirty(page);
+ unlock_page(page);
+ }
+
+ /*
+ * Some of architecture(ex, PPC) don't update TLB
+ * with set_pte_at and tlb_remove_tlb_entry so for
+ * the portability, remap the pte with old|clean
+ * after pte clearing.
+ */
+ ptent = ptep_get_and_clear_full(mm, addr, pte,
+ tlb->fullmm);
+ ptent = pte_mkold(ptent);
+ ptent = pte_mkclean(ptent);
+ set_pte_at(mm, addr, pte, ptent);
+ if (PageActive(page))
+ deactivate_page(page);
+ tlb_remove_tlb_entry(tlb, pte, addr);
+ }
+
+ if (nr_swap) {
+ if (current->mm == mm)
+ sync_mm_rss(mm);
+
+ add_mm_counter(mm, MM_SWAPENTS, nr_swap);
+ }
+
+ arch_leave_lazy_mmu_mode();
+ pte_unmap_unlock(pte - 1, ptl);
+next:
+ cond_resched();
+ return 0;
+}
+
+static void madvise_free_page_range(struct mmu_gather *tlb,
+ struct vm_area_struct *vma,
+ unsigned long addr, unsigned long end)
+{
+ struct mm_walk free_walk = {
+ .pmd_entry = madvise_free_pte_range,
+ .mm = vma->vm_mm,
+ .private = tlb,
+ };
+
+ BUG_ON(addr >= end);
+ tlb_start_vma(tlb, vma);
+ walk_page_range(addr, end, &free_walk);
+ tlb_end_vma(tlb, vma);
+}
+
+static int madvise_free_single_vma(struct vm_area_struct *vma,
+ unsigned long start_addr, unsigned long end_addr)
+{
+ unsigned long start, end;
+ struct mm_struct *mm = vma->vm_mm;
+ struct mmu_gather tlb;
+
+ if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
+ return -EINVAL;
+
+ /* MADV_FREE works for only anon vma at the moment */
+ if (!vma_is_anonymous(vma))
+ return -EINVAL;
+
+ start = max(vma->vm_start, start_addr);
+ if (start >= vma->vm_end)
+ return -EINVAL;
+ end = min(vma->vm_end, end_addr);
+ if (end <= vma->vm_start)
+ return -EINVAL;
+
+ lru_add_drain();
+ tlb_gather_mmu(&tlb, mm, start, end);
+ update_hiwater_rss(mm);
+
+ mmu_notifier_invalidate_range_start(mm, start, end);
+ madvise_free_page_range(&tlb, vma, start, end);
+ mmu_notifier_invalidate_range_end(mm, start, end);
+ tlb_finish_mmu(&tlb, start, end);
+
+ return 0;
+}
+
+static long madvise_free(struct vm_area_struct *vma,
+ struct vm_area_struct **prev,
+ unsigned long start, unsigned long end)
+{
+ *prev = vma;
+ return madvise_free_single_vma(vma, start, end);
+}
+
/*
* Application no longer needs these pages. If the pages are dirty,
* it's OK to just throw them away. The app will be more careful about
return madvise_remove(vma, prev, start, end);
case MADV_WILLNEED:
return madvise_willneed(vma, prev, start, end);
+ case MADV_FREE:
+ /*
+ * XXX: In this implementation, MADV_FREE works like
+ * MADV_DONTNEED on swapless system or full swap.
+ */
+ if (get_nr_swap_pages() > 0)
+ return madvise_free(vma, prev, start, end);
+ /* passthrough */
case MADV_DONTNEED:
return madvise_dontneed(vma, prev, start, end);
default:
case MADV_REMOVE:
case MADV_WILLNEED:
case MADV_DONTNEED:
+ case MADV_FREE:
#ifdef CONFIG_KSM
case MADV_MERGEABLE:
case MADV_UNMERGEABLE:
projects / karo-tx-linux.git / blobdiff