linux 5.15.y: futex_waitv fixup (#676)

following https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v5.15.86&id=fd8a10d44c11f8f53d640db6b97486045b7e0b81

linux-tkg-patches/5.15/0007-v5.15-futex_waitv.patch

@@ -43,7 +43,7 @@ Link: https://lore.kernel.org/r/20210923171111.300673-17-andrealmeid@collabora.c
  include/linux/syscalls.h          |   6 +
  include/uapi/asm-generic/unistd.h |   5 +-
  include/uapi/linux/futex.h        |  26 +++
- kernel/futex.c                    | 334 ++++++++++++++++++++++++++++++
+ kernel/futex/core.c               | 334 ++++++++++++++++++++++++++++++
  kernel/sys_ni.c                   |   1 +
  5 files changed, 371 insertions(+), 1 deletion(-)
 
@@ -125,10 +125,10 @@ index a89eb0accd5e..1666f5e4b837 100644
  /*
   * Support for robust futexes: the kernel cleans up held futexes at
   * thread exit time.
-diff --git a/kernel/futex.c b/kernel/futex.c
+diff --git a/kernel/futex/core.c b/kernel/futex/core.c
 index 408cad5e8968..d7dc0bd9379c 100644
---- a/kernel/futex.c
-+++ b/kernel/futex.c
+--- a/kernel/futex/core.c
++++ b/kernel/futex/core.c
 @@ -285,6 +285,18 @@ static const struct futex_q futex_q_init = {
  	.requeue_state	= ATOMIC_INIT(Q_REQUEUE_PI_NONE),
  };