| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.12 021/106] userfaultfd: non-cooperative: flush event_wqh at release time | Date | Wed, 9 Aug 2017 09:52:05 -0700 |
| |
4.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mike Rapoport <rppt@linux.vnet.ibm.com>
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@linux.vnet.ibm.com Fixes: 9cd75c3cd4c3d ("userfaultfd: non-cooperative: add ability to report non-PF events from uffd descriptor") Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Pavel Emelyanov <xemul@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- 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;
|