Merge tag 'md/4.2-rc5-fixes' of git://neil.brown.name/md

Merge tag 'md/4.2-rc5-fixes' of git://neil.brown.name/md

Pull md fixes from Neil Brown:
 "Three more fixes for md in 4.2

  Mostly corner-case stuff.

  One of these patches is for a CVE: CVE-2015-5697

  I'm not convinced it is serious (data leak from CAP_SYS_ADMIN ioctl)
  but as people seem to want to back-port it, I've included a minimal
  version here.  The remainder of that patch from Benjamin is
  code-cleanup and will arrive in the 4.3 merge window"

* tag 'md/4.2-rc5-fixes' of git://neil.brown.name/md:
  md/raid5: don't let shrink_slab shrink too far.
  md: use kzalloc() when bitmap is disabled
  md/raid1: extend spinlock to protect raid1_end_read_request against inconsistencies