1 files changed, 45 insertions, 0 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 730daa00952b..486f4a2874e7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1361,7 +1361,18 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
 			else if (zap_huge_pmd(tlb, vma, pmd, addr))
 				goto next;
 			/* fall through */
+		} else if (details && details->single_page &&
+			   PageTransCompound(details->single_page) &&
+			   next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) {
+			spinlock_t *ptl = pmd_lock(tlb->mm, pmd);
+			/*
+			 * Take and drop THP pmd lock so that we cannot return
+			 * prematurely, while zap_huge_pmd() has cleared *pmd,
+			 * but not yet decremented compound_mapcount().
+			 */
+			spin_unlock(ptl);
 		}
+
 		/*
 		 * Here there can be other concurrent MADV_DONTNEED or
 		 * trans huge page faults running, and if the pmd is
@@ -2939,6 +2950,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 		}
 		flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
 		entry = mk_pte(new_page, vma->vm_page_prot);
+		entry = pte_sw_mkyoung(entry);
 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
 
 		/*
@@ -3236,6 +3248,36 @@ static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
 }
 
 /**
+ * unmap_mapping_page() - Unmap single page from processes.
+ * @page: The locked page to be unmapped.
+ *
+ * Unmap this page from any userspace process which still has it mmaped.
+ * Typically, for efficiency, the range of nearby pages has already been
+ * unmapped by unmap_mapping_pages() or unmap_mapping_range().  But once
+ * truncation or invalidation holds the lock on a page, it may find that
+ * the page has been remapped again: and then uses unmap_mapping_page()
+ * to unmap it finally.
+ */
+void unmap_mapping_page(struct page *page)
+{
+	struct address_space *mapping = page->mapping;
+	struct zap_details details = { };
+
+	VM_BUG_ON(!PageLocked(page));
+	VM_BUG_ON(PageTail(page));
+
+	details.check_mapping = mapping;
+	details.first_index = page->index;
+	details.last_index = page->index + thp_nr_pages(page) - 1;
+	details.single_page = page;
+
+	i_mmap_lock_write(mapping);
+	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
+		unmap_mapping_range_tree(&mapping->i_mmap, &details);
+	i_mmap_unlock_write(mapping);
+}
+
+/**
  * unmap_mapping_pages() - Unmap pages from processes.
  * @mapping: The address space containing pages to be unmapped.
  * @start: Index of first page to be unmapped.
@@ -3602,6 +3644,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 	__SetPageUptodate(page);
 
 	entry = mk_pte(page, vma->vm_page_prot);
+	entry = pte_sw_mkyoung(entry);
 	if (vma->vm_flags & VM_WRITE)
 		entry = pte_mkwrite(pte_mkdirty(entry));
 
@@ -3786,6 +3829,8 @@ void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
 
 	if (prefault && arch_wants_old_prefaulted_pte())
 		entry = pte_mkold(entry);
+	else
+		entry = pte_sw_mkyoung(entry);
 
 	if (write)
 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);