diff options
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index e42d89f98071..d0dfc85b209b 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1410,6 +1410,36 @@ unsigned long do_mmap(struct file *file, unsigned long addr, pgoff = 0; vm_flags |= VM_SHARED | VM_MAYSHARE; break; + case MAP_DROPPABLE: + if (VM_DROPPABLE == VM_NONE) + return -ENOTSUPP; + /* + * A locked or stack area makes no sense to be droppable. + * + * Also, since droppable pages can just go away at any time + * it makes no sense to copy them on fork or dump them. + * + * And don't attempt to combine with hugetlb for now. + */ + if (flags & (MAP_LOCKED | MAP_HUGETLB)) + return -EINVAL; + if (vm_flags & (VM_GROWSDOWN | VM_GROWSUP)) + return -EINVAL; + + vm_flags |= VM_DROPPABLE; + + /* + * If the pages can be dropped, then it doesn't make + * sense to reserve them. + */ + vm_flags |= VM_NORESERVE; + + /* + * Likewise, they're volatile enough that they + * shouldn't survive forks or coredumps. + */ + vm_flags |= VM_WIPEONFORK | VM_DONTDUMP; + fallthrough; case MAP_PRIVATE: /* * Set pgoff according to addr for anon_vma. |