diff --git a/mm/mmap.c b/mm/mmap.c
index 7bdfd26..505a454 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -970,6 +970,7 @@
 			return -EPERM;
 		vm_flags |= VM_LOCKED;
 	}
+
 	/* mlock MCL_FUTURE? */
 	if (vm_flags & VM_LOCKED) {
 		unsigned long locked, lock_limit;
@@ -1137,10 +1138,12 @@
 	 * The VM_SHARED test is necessary because shmem_zero_setup
 	 * will create the file object for a shared anonymous map below.
 	 */
-	if (!file && !(vm_flags & VM_SHARED) &&
-	    vma_merge(mm, prev, addr, addr + len, vm_flags,
-					NULL, NULL, pgoff, NULL))
-		goto out;
+	if (!file && !(vm_flags & VM_SHARED)) {
+		vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
+					NULL, NULL, pgoff, NULL);
+		if (vma)
+			goto out;
+	}
 
 	/*
 	 * Determine the object being mapped and call the appropriate
@@ -1222,10 +1225,14 @@
 	mm->total_vm += len >> PAGE_SHIFT;
 	vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
 	if (vm_flags & VM_LOCKED) {
-		mm->locked_vm += len >> PAGE_SHIFT;
-		make_pages_present(addr, addr + len);
-	}
-	if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
+		/*
+		 * makes pages present; downgrades, drops, reacquires mmap_sem
+		 */
+		long nr_pages = mlock_vma_pages_range(vma, addr, addr + len);
+		if (nr_pages < 0)
+			return nr_pages;	/* vma gone! */
+		mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages;
+	} else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
 		make_pages_present(addr, addr + len);
 	return addr;
 
@@ -1698,8 +1705,10 @@
 		return vma;
 	if (!prev || expand_stack(prev, addr))
 		return NULL;
-	if (prev->vm_flags & VM_LOCKED)
-		make_pages_present(addr, prev->vm_end);
+	if (prev->vm_flags & VM_LOCKED) {
+		if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0)
+			return NULL;	/* vma gone! */
+	}
 	return prev;
 }
 #else
@@ -1725,8 +1734,10 @@
 	start = vma->vm_start;
 	if (expand_stack(vma, addr))
 		return NULL;
-	if (vma->vm_flags & VM_LOCKED)
-		make_pages_present(addr, start);
+	if (vma->vm_flags & VM_LOCKED) {
+		if (mlock_vma_pages_range(vma, addr, start) < 0)
+			return NULL;	/* vma gone! */
+	}
 	return vma;
 }
 #endif
@@ -1745,8 +1756,6 @@
 		long nrpages = vma_pages(vma);
 
 		mm->total_vm -= nrpages;
-		if (vma->vm_flags & VM_LOCKED)
-			mm->locked_vm -= nrpages;
 		vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
 		vma = remove_vma(vma);
 	} while (vma);
@@ -1912,6 +1921,20 @@
 	vma = prev? prev->vm_next: mm->mmap;
 
 	/*
+	 * unlock any mlock()ed ranges before detaching vmas
+	 */
+	if (mm->locked_vm) {
+		struct vm_area_struct *tmp = vma;
+		while (tmp && tmp->vm_start < end) {
+			if (tmp->vm_flags & VM_LOCKED) {
+				mm->locked_vm -= vma_pages(tmp);
+				munlock_vma_pages_all(tmp);
+			}
+			tmp = tmp->vm_next;
+		}
+	}
+
+	/*
 	 * Remove the vma's, and unmap the actual pages
 	 */
 	detach_vmas_to_be_unmapped(mm, vma, prev, end);
@@ -2023,8 +2046,9 @@
 		return -ENOMEM;
 
 	/* Can we just expand an old private anonymous mapping? */
-	if (vma_merge(mm, prev, addr, addr + len, flags,
-					NULL, NULL, pgoff, NULL))
+	vma = vma_merge(mm, prev, addr, addr + len, flags,
+					NULL, NULL, pgoff, NULL);
+	if (vma)
 		goto out;
 
 	/*
@@ -2046,8 +2070,8 @@
 out:
 	mm->total_vm += len >> PAGE_SHIFT;
 	if (flags & VM_LOCKED) {
-		mm->locked_vm += len >> PAGE_SHIFT;
-		make_pages_present(addr, addr + len);
+		if (!mlock_vma_pages_range(vma, addr, addr + len))
+			mm->locked_vm += (len >> PAGE_SHIFT);
 	}
 	return addr;
 }
@@ -2058,7 +2082,7 @@
 void exit_mmap(struct mm_struct *mm)
 {
 	struct mmu_gather *tlb;
-	struct vm_area_struct *vma = mm->mmap;
+	struct vm_area_struct *vma;
 	unsigned long nr_accounted = 0;
 	unsigned long end;
 
@@ -2066,6 +2090,15 @@
 	arch_exit_mmap(mm);
 	mmu_notifier_release(mm);
 
+	if (mm->locked_vm) {
+		vma = mm->mmap;
+		while (vma) {
+			if (vma->vm_flags & VM_LOCKED)
+				munlock_vma_pages_all(vma);
+			vma = vma->vm_next;
+		}
+	}
+	vma = mm->mmap;
 	lru_add_drain();
 	flush_cache_mm(mm);
 	tlb = tlb_gather_mmu(mm, 1);