From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Subject: userfaultfd_copy: return -ENOSPC in case mm has gone In the non-cooperative userfaultfd case, the process exit may race with outstanding mcopy_atomic called by the uffd monitor. Returning -ENOSPC instead of -EINVAL when mm is already gone will allow uffd monitor to distinguish this case from other error conditions. Link: http://lkml.kernel.org/r/1485542673-24387-6-git-send-email-rppt@xxxxxxxxxxxxxxxxxx Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Acked-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/userfaultfd.c | 2 ++ 1 file changed, 2 insertions(+) diff -puN fs/userfaultfd.c~userfaultfd_copy-return-enospc-in-case-mm-has-gone fs/userfaultfd.c --- a/fs/userfaultfd.c~userfaultfd_copy-return-enospc-in-case-mm-has-gone +++ a/fs/userfaultfd.c @@ -1607,6 +1607,8 @@ static int userfaultfd_copy(struct userf ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src, uffdio_copy.len); mmput(ctx->mm); + } else { + return -ENOSPC; } if (unlikely(put_user(ret, &user_uffdio_copy->copy))) return -EFAULT; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
