[mmotm] mm: _install_special_mapping() apply VM_LOCKED_CLEAR_MASK

Commit Message

Hugh Dickins March 3, 2022, 1:38 a.m. UTC

_install_special_mapping() adds the VM_SPECIAL bit VM_DONTEXPAND (and
never attempts to update locked_vm), so it ought to be consistent with
mmap_region() and mlock_fixup(), making sure not to add VM_LOCKED or
VM_LOCKONFAULT.  I doubt that this fixes any problem in practice: just
do it for consistency.

Signed-off-by: Hugh Dickins <[e-mail]>
---
Noticed in doing mm/munlock series, but not needed as a part of that.

 mm/mmap.c | 1 +
 1 file changed, 1 insertion(+)

Patch

--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3420,6 +3420,7 @@  static struct vm_area_struct *__install_special_mapping(
 	vma->vm_end = addr + len;
 
 	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
+	vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
 	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 
 	vma->vm_ops = ops;