1 files changed, 218 insertions, 2 deletions

diff --git a/mm/madvise.c b/mm/madvise.c
index c889fcbb530e..a01147359f3b 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
@@ -363,8 +555,9 @@ static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end)
 		}
 		pr_info("Injecting memory failure for page %#lx at %#lx\n",
 		       page_to_pfn(p), start);
-		/* Ignore return value for now */
-		memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
+		ret = memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
+		if (ret)
+			return ret;
 	}
 	return 0;
 }
@@ -379,6 +572,14 @@ 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 +599,7 @@ 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:
@@ -437,14 +639,28 @@ madvise_behavior_valid(int behavior)
  *		some pages ahead.
  *  MADV_DONTNEED - the application is finished with the given range,
  *		so the kernel can free resources associated with it.
+ *  MADV_FREE - the application marks pages in the given range as lazy free,
+ *		where actual purges are postponed until memory pressure happens.
  *  MADV_REMOVE - the application wants to free up the given range of
  *		pages and associated backing store.
  *  MADV_DONTFORK - omit this area from child's address space when forking:
  *		typically, to avoid COWing pages pinned by get_user_pages().
  *  MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
+ *  MADV_HWPOISON - trigger memory error handler as if the given memory range
+ *		were corrupted by unrecoverable hardware memory failure.
+ *  MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
  *  MADV_MERGEABLE - the application recommends that KSM try to merge pages in
  *		this area with pages of identical content from other such areas.
  *  MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
+ *  MADV_HUGEPAGE - the application wants to back the given range by transparent
+ *		huge pages in the future. Existing pages might be coalesced and
+ *		new pages might be allocated as THP.
+ *  MADV_NOHUGEPAGE - mark the given range as not worth being backed by
+ *		transparent huge pages so the existing pages will not be
+ *		coalesced into THP and new pages will not be allocated as THP.
+ *  MADV_DONTDUMP - the application wants to prevent pages in the given range
+ *		from being included in its core dump.
+ *  MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
  *
  * return values:
  *  zero    - success