mm: use mm_populate() for mremap() of VM_LOCKED vmas

Signed-off-by: NMichel Lespinasse <walken@google.com>
Acked-by: NRik van Riel <riel@redhat.com>
Tested-by: NAndy Lutomirski <luto@amacapital.net>
Cc: Greg Ungerer <gregungerer@westnet.com.au>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/mremap.c

@@ -209,7 +209,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
 
 static unsigned long move_vma(struct vm_area_struct *vma,
 		unsigned long old_addr, unsigned long old_len,
-		unsigned long new_len, unsigned long new_addr)
+		unsigned long new_len, unsigned long new_addr, bool *locked)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	struct vm_area_struct *new_vma;
@@ -300,9 +300,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
 
 	if (vm_flags & VM_LOCKED) {
 		mm->locked_vm += new_len >> PAGE_SHIFT;
-		if (new_len > old_len)
-			mlock_vma_pages_range(new_vma, new_addr + old_len,
-						       new_addr + new_len);
+		*locked = true;
 	}
 
 	return new_addr;
@@ -367,9 +365,8 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
 	return ERR_PTR(-EAGAIN);
 }
 
-static unsigned long mremap_to(unsigned long addr,
-	unsigned long old_len, unsigned long new_addr,
-	unsigned long new_len)
+static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
+		unsigned long new_addr, unsigned long new_len, bool *locked)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
@@ -419,7 +416,7 @@ static unsigned long mremap_to(unsigned long addr,
 	if (ret & ~PAGE_MASK)
 		goto out1;
 
-	ret = move_vma(vma, addr, old_len, new_len, new_addr);
+	ret = move_vma(vma, addr, old_len, new_len, new_addr, locked);
 	if (!(ret & ~PAGE_MASK))
 		goto out;
 out1:
@@ -457,6 +454,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 	struct vm_area_struct *vma;
 	unsigned long ret = -EINVAL;
 	unsigned long charged = 0;
+	bool locked = false;
 
 	down_write(&current->mm->mmap_sem);
 
@@ -479,7 +477,8 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 
 	if (flags & MREMAP_FIXED) {
 		if (flags & MREMAP_MAYMOVE)
-			ret = mremap_to(addr, old_len, new_addr, new_len);
+			ret = mremap_to(addr, old_len, new_addr, new_len,
+					&locked);
 		goto out;
 	}
 
@@ -521,8 +520,8 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 			vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
 			if (vma->vm_flags & VM_LOCKED) {
 				mm->locked_vm += pages;
-				mlock_vma_pages_range(vma, addr + old_len,
-						   addr + new_len);
+				locked = true;
+				new_addr = addr;
 			}
 			ret = addr;
 			goto out;
@@ -548,11 +547,13 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 			goto out;
 		}
 
-		ret = move_vma(vma, addr, old_len, new_len, new_addr);
+		ret = move_vma(vma, addr, old_len, new_len, new_addr, &locked);
 	}
 out:
 	if (ret & ~PAGE_MASK)
 		vm_unacct_memory(charged);
 	up_write(&current->mm->mmap_sem);
+	if (locked && new_len > old_len)
+		mm_populate(new_addr + old_len, new_len - old_len);
 	return ret;
 }