Patch "userfaultfd: non-cooperative: flush event_wqh at release time" 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: non-cooperative: flush event_wqh at release time

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-non-cooperative-flush-event_wqh-at-release-time.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 13:32:24 -0700
Subject: userfaultfd: non-cooperative: flush event_wqh at release time

From: Mike Rapoport <[email protected]>

commit 5a18b64e3f02125be1c0ef777501ae38aafe2a24 upstream.

There may still be threads waiting on event_wqh at the time the userfault file descriptor is closed. Flush the events wait-queue to prevent waiting threads from hanging.

non-PF events from uffd descriptor")

---
 fs/userfaultfd.c |    3 +++
 1 file changed, 3 insertions(+)

@@ -851,6 +851,9 @@ wakeup:
 	__wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, &range);
 	spin_unlock(&ctx->fault_pending_wqh.lock);
 
+	/* Flush pending events that may still wait on event_wqh */
+	wake_up_all(&ctx->event_wqh);
+
 	wake_up_poll(&ctx->fd_wqh, POLLHUP);
 	userfaultfd_ctx_put(ctx);
 	return 0;

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