From 5a18b64e3f02125be1c0ef777501ae38aafe2a24 Mon Sep 17 00:00:00 2001 From: Mike Rapoport Date: Wed, 2 Aug 2017 13:32:24 -0700 Subject: [PATCH] userfaultfd: non-cooperative: flush event_wqh at release time 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 Cc: Andrea Arcangeli Cc: "Dr. David Alan Gilbert" Cc: Pavel Emelyanov Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/userfaultfd.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 2d8c2d848668..06ea26b8c996 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -854,6 +854,9 @@ 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; -- 2.20.1