Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2021-08-19

We've added 3 non-merge commits during the last 3 day(s) which contain
a total of 3 files changed, 29 insertions(+), 6 deletions(-).

The main changes are:

1) Fix to clear zext_dst for dead instructions which was causing invalid program
   rejections on JITs with bpf_jit_needs_zext such as s390x, from Ilya Leoshkevich.

2) Fix RCU splat in bpf_get_current_{ancestor_,}cgroup_id() helpers when they are
   invoked from sleepable programs, from Yonghong Song.

* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  selftests, bpf: Test that dead ldx_w insns are accepted
  bpf: Clear zext_dst of dead insns
  bpf: Add rcu_read_lock in bpf_get_current_[ancestor_]cgroup_id() helpers
====================

Link: https://lore.kernel.org/r/20210819144904.20069-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>