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 <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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 2d8c2d8..06ea26b 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -854,6 +854,9 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
__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;
