From: Peter Zijlstra Userspace can (malisiously) munmap() the VMAs injected into its memory map through install_special_mapping(). In order to ensure there are no hardware resources tied to the mapping, we need a close callback. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner --- include/linux/mm_types.h | 3 +++ mm/mmap.c | 4 ++++ 2 files changed, 7 insertions(+) --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -644,6 +644,9 @@ struct vm_special_mapping { int (*mremap)(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma); + + void (*close)(const struct vm_special_mapping *sm, + struct vm_area_struct *vma); }; enum tlb_flush_reason { --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3206,6 +3206,10 @@ static int special_mapping_fault(struct */ static void special_mapping_close(struct vm_area_struct *vma) { + struct vm_special_mapping *sm = vma->vm_private_data; + + if (sm->close) + sm->close(sm, vma); } static const char *special_mapping_name(struct vm_area_struct *vma)