From 9d95aa4bada24be35bb94827a55e1d6e243d866e Mon Sep 17 00:00:00 2001 From: Mike Rapoport Date: Wed, 2 Aug 2017 13:32:15 -0700 Subject: [PATCH] userfaultfd_zeropage: 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. Unfortunately I overlooked userfaultfd_zeropage when updating userfaultd_copy(). Link: http://lkml.kernel.org/r/1501136819-21857-1-git-send-email-rppt@linux.vnet.ibm.com Fixes: 96333187ab162 ("userfaultfd_copy: return -ENOSPC in case mm has gone") Signed-off-by: Mike Rapoport Cc: Andrea Arcangeli Cc: "Dr. David Alan Gilbert" Cc: Pavel Emelyanov Cc: Michal Hocko Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/userfaultfd.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index cadcd12a3d35..2d8c2d848668 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1643,6 +1643,8 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx, ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start, uffdio_zeropage.range.len); mmput(ctx->mm); + } else { + return -ENOSPC; } if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage))) return -EFAULT; -- 2.20.1