Merge branch 'bpf-stackmap-nmi'

Merge branch 'bpf-stackmap-nmi'

Song Liu says:
====================
Changes v2 -> v3:
  Improve syntax based on suggestion by Tobin C. Harding.

Changes v1 -> v2:
  1. Rename some variables to (hopefully) reduce confusion;
  2. Check irq_work status with IRQ_WORK_BUSY (instead of work->sem);
  3. In Kconfig, let BPF_SYSCALL select IRQ_WORK;
  4. Add static to DEFINE_PER_CPU();
   5. Remove pr_info() in stack_map_init().
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>