Comment 86 for bug 1124250

This is what I use on our Fedora machines (1000 is enough for us ATM):

/etc/sysctl.d/nfsv4_idmap_maxkeys:

  # NFSv4 idmap entries are counted against a very low quota
  # https://bugzilla.redhat.com/show_bug.cgi?id=876705
  kernel.keys.root_maxkeys = 1000
  kernel.keys.maxkeys = 1000