diff options
Diffstat (limited to 'mm/madvise.c')
| -rw-r--r-- | mm/madvise.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/mm/madvise.c b/mm/madvise.c index c889fcbb5..f56825b6d 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -20,6 +20,9 @@ #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 @@ -32,6 +35,7 @@ static int madvise_need_mmap_write(int behavior) case MADV_REMOVE: case MADV_WILLNEED: case MADV_DONTNEED: + case MADV_FREE: return 0; default: /* be safe, default to 1. list exceptions explicitly */ @@ -256,6 +260,194 @@ static long madvise_willneed(struct vm_area_struct *vma, 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 *orig_pte, *pte, ptent; + struct page *page; + int nr_swap = 0; + unsigned long next; + + next = pmd_addr_end(addr, end); + if (pmd_trans_huge(*pmd)) + if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next)) + goto next; + + if (pmd_trans_unstable(pmd)) + return 0; + + orig_pte = 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)) { + swp_entry_t entry; + + 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 pmd isn't transhuge but the page is THP and + * is owned by only this process, split it and + * deactivate all pages. + */ + if (PageTransCompound(page)) { + if (page_mapcount(page) != 1) + goto out; + get_page(page); + if (!trylock_page(page)) { + put_page(page); + goto out; + } + pte_unmap_unlock(orig_pte, ptl); + if (split_huge_page(page)) { + unlock_page(page); + put_page(page); + pte_offset_map_lock(mm, pmd, addr, &ptl); + goto out; + } + put_page(page); + unlock_page(page); + pte = pte_offset_map_lock(mm, pmd, addr, &ptl); + pte--; + addr -= PAGE_SIZE; + continue; + } + + VM_BUG_ON_PAGE(PageTransCompound(page), page); + + 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_mapcount(page) != 1) { + unlock_page(page); + continue; + } + + if (PageSwapCache(page) && !try_to_free_swap(page)) { + unlock_page(page); + continue; + } + + ClearPageDirty(page); + unlock_page(page); + } + + if (pte_young(ptent) || pte_dirty(ptent)) { + /* + * 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); + } + } +out: + 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(orig_pte, ptl); + cond_resched(); +next: + 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, + }; + + 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 @@ -379,6 +571,14 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, 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: @@ -398,6 +598,7 @@ madvise_behavior_valid(int behavior) case MADV_REMOVE: case MADV_WILLNEED: case MADV_DONTNEED: + case MADV_FREE: #ifdef CONFIG_KSM case MADV_MERGEABLE: case MADV_UNMERGEABLE: |