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 <stable@xxxxxxxxxxxxxxx> know about it.
>From 5a18b64e3f02125be1c0ef777501ae38aafe2a24 Mon Sep 17 00:00:00 2001
From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Date: Wed, 2 Aug 2017 13:32:24 -0700
Subject: userfaultfd: non-cooperative: flush event_wqh at release time
From: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
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.
Link: http://lkml.kernel.org/r/1501398127-30419-1-git-send-email-rppt@xxxxxxxxxxxxxxxxxx
Fixes: 9cd75c3cd4c3d ("userfaultfd: non-cooperative: add ability to report
non-PF events from uffd descriptor")
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/userfaultfd.c | 3 +++
1 file changed, 3 insertions(+)
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -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 rppt@xxxxxxxxxxxxxxxxxx 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