path: root/mm
diff options
authorMike Rapoport <>2017-02-24 14:58:19 -0800
committerLinus Torvalds <>2017-02-24 17:46:55 -0800
commit846b1a0f1db065a8479159dd8fecddb1ebf30547 (patch)
tree20d44a1d5c0c4dabea2fae8cc7223d578de14e3a /mm
parent3fe87967c536e828bf1ea14b3ec3827d1101152e (diff)
mm: call vm_munmap in munmap syscall instead of using open coded version
Patch series "userfaultfd: non-cooperative: better tracking for mapping changes", v2. These patches try to address issues I've encountered during integration of userfaultfd with CRIU. Previously added userfaultfd events for fork(), madvise() and mremap() unfortunately do not cover all possible changes to a process virtual memory layout required for uffd monitor. When one or more VMAs is removed from the process mm, the external uffd monitor has no way to detect those changes and will attempt to fill the removed regions with userfaultfd_copy. Another problematic event is the exit() of the process. Here again, the external uffd monitor will try to use userfaultfd_copy, although mm owning the memory has already gone. The first patch in the series is a minor cleanup and it's not strictly related to the rest of the series. The patches 2 and 3 below add UFFD_EVENT_UNMAP and UFFD_EVENT_EXIT to allow the uffd monitor track changes in the memory layout of a process. The patches 4 and 5 amend error codes returned by userfaultfd_copy to make the uffd monitor able to cope with races that might occur between delivery of unmap and exit events and outstanding userfaultfd_copy's. This patch (of 5): Commit dc0ef0df7b6a ("mm: make mmap_sem for write waits killable for mm syscalls") replaced call to vm_munmap in munmap syscall with open coded version to allow different waits on mmap_sem in munmap syscall and vm_munmap. Now both functions use down_write_killable, so we can restore the call to vm_munmap from the munmap system call. Link: Signed-off-by: Mike Rapoport <> Acked-by: Hillf Danton <> Cc: Andrea Arcangeli <> Cc: "Dr. David Alan Gilbert" <> Cc: Mike Kravetz <> Cc: Pavel Emelyanov <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm')
1 files changed, 1 insertions, 8 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index 46059b7..13d16a2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2680,15 +2680,8 @@ EXPORT_SYMBOL(vm_munmap);
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
- int ret;
- struct mm_struct *mm = current->mm;
- if (down_write_killable(&mm->mmap_sem))
- return -EINTR;
- ret = do_munmap(mm, addr, len);
- up_write(&mm->mmap_sem);
- return ret;
+ return vm_munmap(addr, len);