userfaultfd: use fault_wqh lock

The userfaultfd code currently uses the unlocked waitqueue helpers for
managing fault_wqh, but instead of holding the waitqueue lock for this
waitqueue around these calls, it the waitqueue lock of
fault_pending_wq, which is a different waitqueue instance.  Given that
the waitqueue is not exposed to the rest of the kernel this actually
works ok at the moment, but prevents the userfaultfd locking rules from
being enforced using lockdep.

Switch to the internally locked waitqueue helpers instead.  This means
that the lock inside fault_wqh now nests inside the fault_pending_wqh
lock, but that's not a problem since it was entirely unused before.

[[email protected]: slight changelog updates]
[[email protected]: spotted changelog spellos]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Mike Rapoport <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jason Baron <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 15c265d450bf..f649023b19b5 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -910,7 +910,7 @@ wakeup:
 	 */
 	spin_lock(&ctx->fault_pending_wqh.lock);
 	__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, &range);
-	__wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, &range);
+	__wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, &range);
 	spin_unlock(&ctx->fault_pending_wqh.lock);
 
 	/* Flush pending events that may still wait on event_wqh */
@@ -1066,7 +1066,7 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
 			 * anyway.
 			 */
 			list_del(&uwq->wq.entry);
-			__add_wait_queue(&ctx->fault_wqh, &uwq->wq);
+			add_wait_queue(&ctx->fault_wqh, &uwq->wq);
 
 			write_seqcount_end(&ctx->refile_seq);
 
@@ -1215,7 +1215,7 @@ static void __wake_userfault(struct userfaultfd_ctx *ctx,
 		__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL,
 				     range);
 	if (waitqueue_active(&ctx->fault_wqh))
-		__wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, range);
+		__wake_up(&ctx->fault_wqh, TASK_NORMAL, 1, range);
 	spin_unlock(&ctx->fault_pending_wqh.lock);
 }