Merge branch 'akpm' (patches from Andrew)

Merge misc fixes from Andrew Morton:
 "18 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm, swap: use page-cluster as max window of VMA based swap readahead
  mm: page_vma_mapped: ensure pmd is loaded with READ_ONCE outside of lock
  kmemleak: clear stale pointers from task stacks
  fs/binfmt_misc.c: node could be NULL when evicting inode
  fs/mpage.c: fix mpage_writepage() for pages with buffers
  linux/kernel.h: add/correct kernel-doc notation
  tty: fall back to N_NULL if switching to N_TTY fails during hangup
  Revert "vmalloc: back off when the current task is killed"
  mm/cma.c: take __GFP_NOWARN into account in cma_alloc()
  scripts/kallsyms.c: ignore symbol type 'n'
  userfaultfd: selftest: exercise -EEXIST only in background transfer
  mm: only display online cpus of the numa node
  mm: remove unnecessary WARN_ONCE in page_vma_mapped_walk().
  mm/mempolicy: fix NUMA_INTERLEAVE_HIT counter
  include/linux/of.h: provide of_n_{addr,size}_cells wrappers for !CONFIG_OF
  mm/madvise.c: add description for MADV_WIPEONFORK and MADV_KEEPONFORK
  lib/Kconfig.debug: kernel hacking menu: runtime testing: keep tests together
  mm/migrate: fix indexing bug (off by one) and avoid out of bound access