- late-breaking ocfs2 updates

- random bunch of fixes

19 patches, based on dc03c0f9d12d85286d5e3623aa96d5c2a271b8e6:

Subject: ocfs2: o2hb: add negotiate timer
Subject: ocfs2: o2hb: add NEGO_TIMEOUT message
Subject: ocfs2: o2hb: add NEGOTIATE_APPROVE message
Subject: ocfs2: o2hb: add some user/debug log
Subject: ocfs2: o2hb: don't negotiate if last hb fail
Subject: ocfs2: o2hb: fix hb hung time
Subject: ocfs2: bump up o2cb network protocol version
Subject: direct-io: fix direct write stale data exposure from concurrent buffered read
Subject: mm: oom: do not reap task if there are live threads in threadgroup
Subject: MAINTAINERS: add kexec_core.c and kexec_file.c
Subject: MAINTAINERS: Kdump maintainers update
Subject: mm: use early_pfn_to_nid in page_ext_init
Subject: mm: use early_pfn_to_nid in register_page_bootmem_info_node
Subject: oom_reaper: close race with exiting task
Subject: mm: thp: avoid false positive VM_BUG_ON_PAGE in page_move_anon_rmap()
Subject: mm/cma: silence warnings due to max() usage
Subject: mm/memcontrol.c: fix the margin computation in mem_cgroup_margin()
Subject: mm/memcontrol.c: move comments for get_mctgt_type() to proper position
Subject: mm: disable DEFERRED_STRUCT_PAGE_INIT on !NO_BOOTMEM