I have installed Elasticsearch 2.1.0
<p>After configuring and installing Elasticsearch I got this error while checking the logs.</p>

<pre><code>[2016-01-25 15:37:33,223][WARN ][bootstrap                ] Unable to lock JVM Memory: error=12,reason=Cannot allocate memory
[2016-01-25 15:37:33,223][WARN ][bootstrap                ] This can result in part of the JVM being swapped out.
[2016-01-25 15:37:33,224][WARN ][bootstrap                ] Increase RLIMIT_MEMLOCK, soft limit: 65536, hard limit: 65536
[2016-01-25 15:37:33,224][WARN ][bootstrap                ] These can be adjusted by modifying /etc/security/limits.conf, for example:
        # allow user 'elasticsearch' mlockall
        elasticsearch soft memlock unlimited
        elasticsearch hard memlock unlimited
[2016-01-25 15:37:33,224][WARN ][bootstrap                ] If you are logged in interactively, you will have to re-login for the new limits to take effect.
[2016-01-25 15:37:33,428][INFO ][node                     ] [node-1] version[2.1.0], pid[13298], build[72cd1f1/2015-11-18T22:40:03Z]
[2016-01-25 15:37:33,428][INFO ][node                     ] [node-1] initializing ...
[2016-01-25 15:37:33,508][INFO ][plugins                  ] [node-1] loaded [], sites []
[2016-01-25 15:37:33,528][INFO ][env                      ] [node-1] using [1] data paths, mounts [[/ (rootfs)]], net usable_space [43.8gb], net total_space [49.9gb], spins? [unknown], types [rootfs]
[2016-01-25 15:37:35,022][INFO ][node                     ] [node-1] initialized
[2016-01-25 15:37:35,022][INFO ][node                     ] [node-1] starting ...
[2016-01-25 15:37:35,088][INFO ][transport                ] [node-1] publish_address {10.155.153.74:9300}, bound_addresses {10.155.153.74:9300}
[2016-01-25 15:37:35,097][INFO ][discovery                ] [node-1] Elasticsearch/M0pCcU6UQ1ShHxlOZ4U22w
[2016-01-25 15:37:38,157][INFO ][cluster.service          ] [node-1] new_master {node-1}{M0pCcU6UQ1ShHxlOZ4U22w}{10.155.153.74}{10.155.153.74:9300}{master=true}, reason: zen-disco-join(elected_as_master, [0] joins received)
[2016-01-25 15:37:38,195][INFO ][http                     ] [node-1] publish_address {10.155.153.74:9200}, bound_addresses {10.155.153.74:9200}
[2016-01-25 15:37:38,196][INFO ][node                     ] [node-1] started
[2016-01-25 15:37:38,250][INFO ][gateway                  ] [node-1] recovered [0] indices into cluster_state
[2016-01-25 15:37:45,458][INFO ][cluster.metadata         ] [node-1] [.kibana] creating index, cause [api], templates [], shards [1]/[1], mappings [config
</code></pre>

<p>I checked for bootstrap.mlockall: true too . 
Elasticsearch.yml file</p>

<pre><code># ======================== Elasticsearch Configuration =========================
#
# NOTE: Elasticsearch comes with reasonable defaults for most settings.
#       Before you set out to tweak and tune the configuration, make sure you
#       understand what are you trying to accomplish and the consequences.
#
# The primary way of configuring a node is via this file. This template lists
# the most important settings you may want to configure for a production cluster.
#
# Please see the documentation for further information on configuration options:
# &lt;http://www.elastic.co/guide/en/elasticsearch/reference/current/setup-configuration.html&gt;
#
# ---------------------------------- Cluster -----------------------------------
#
# Use a descriptive name for your cluster:
#
  cluster.name: Elasticsearch
#
# ------------------------------------ Node ------------------------------------
#
# Use a descriptive name for the node:
#
  node.name: node-1
  node.master: true
  node.data: true
#
# Add custom attributes to the node:
#
# node.rack: r1
#
# ----------------------------------- Paths ------------------------------------
#
# Path to directory where to store the data (separate multiple locations by comma):
#
# path.data: /path/to/data
#
# Path to log files:
#
# path.logs: /path/to/logs
#
# ----------------------------------- Memory -----------------------------------
#
# Lock the memory on startup:
#
  bootstrap.mlockall: true
#
# Make sure that the `ES_HEAP_SIZE` environment variable is set to about half the memory
# available on the system and that the owner of the process is allowed to use this limit.
#
# Elasticsearch performs poorly when the system is swapping the memory.
#
# ---------------------------------- Network -----------------------------------
#
# Set the bind address to a specific IP (IPv4 or IPv6):
#
  network.host: 10.155.153.74
  network.publish_host: 10.155.153.74
  network.bind_host: 10.155.153.74
#
# Set a custom port for HTTP:
#
  http.port: 9200
  discovery.zen.ping.multicast.enabled: false

# http.cors.enabled: true
# http.cors.allow-origin: http://tvmatp326579d.ad.infosys.com:5601/
#
# For more information, see the documentation at:
# &lt;http://www.elastic.co/guide/en/elasticsearch/reference/current/modules-network.html&gt;
#
# ---------------------------------- Gateway -----------------------------------
#
# Block initial recovery after a full cluster restart until N nodes are started:
#
# gateway.recover_after_nodes: 3
#
# For more information, see the documentation at:
# &lt;http://www.elastic.co/guide/en/elasticsearch/reference/current/modules-gateway.html&gt;
#
# --------------------------------- Discovery ----------------------------------
#
# Elasticsearch nodes will find each other via unicast, by default.
#
# Pass an initial list of hosts to perform discovery when new node is started:
# The default list of hosts is ["127.0.0.1", "[::1]"]
#
# discovery.zen.ping.unicast.hosts: ["host1", "host2"]
#
# Prevent the "split brain" by configuring the majority of nodes (total number of nodes / 2 + 1):
#
# discovery.zen.minimum_master_nodes: 3
#
# For more information, see the documentation at:
# &lt;http://www.elastic.co/guide/en/elasticsearch/reference/current/modules-discovery.html&gt;
#
# ---------------------------------- Various -----------------------------------
#
# Disable starting multiple nodes on a single system:
#
# node.max_local_storage_nodes: 1
#
# Require explicit names when deleting indices:
#
# action.destructive_requires_name: true
</code></pre>

<p>Can anybody tell what could be the issue? why ES is not able to lock JVM memory?</p>

<p>update:</p>

<p><a href="https://i.stack.imgur.com/0bQds.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0bQds.jpg" alt="enter image description here"></a></p>

<p><a href="https://i.stack.imgur.com/8KRph.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8KRph.jpg" alt="enter image description here"></a></p>