Patch "userfaultfd_zeropage: return -ENOSPC in case mm has gone" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

userfaultfd_zeropage: return -ENOSPC in case mm has gone

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
userfaultfd_zeropage-return-enospc-in-case-mm-has-gone.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Mike Rapoport <[email protected]>
Date: Wed, 2 Aug 2017 13:32:15 -0700
Subject: userfaultfd_zeropage: return -ENOSPC in case mm has gone

From: Mike Rapoport <[email protected]>

commit 9d95aa4bada24be35bb94827a55e1d6e243d866e upstream.

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().

---
 fs/userfaultfd.c |    2 ++
 1 file changed, 2 insertions(+)

@@ -1645,6 +1645,8 @@ static int userfaultfd_zeropage(struct u
 		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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/userfaultfd-non-cooperative-flush-event_wqh-at-release-time.patch queue-4.12/userfaultfd_zeropage-return-enospc-in-case-mm-has-gone.patch queue-4.12/userfaultfd-non-cooperative-notify-about-unmap-of-destination-during-mremap.patch