ecryptfs_write_end: Error encrypting page (upper index [0x000000000000011e])

I get these strange and worrying errors:

[ 185.714463] ecryptfs_decrypt_page: Error attempting to read lower page; rc = [-4]
[ 185.714482] ecryptfs_readpage: Error decrypting page; rc = [-4]
[ 186.716177] ecryptfs_encrypt_page: Error attempting to write lower page; rc = [-4]
[ 186.716199] ecryptfs_write_end: Error encrypting page (upper index [0x000000000000011e])

The system seems to freeze for a second and then continues.

smart says that the hard-drive is fine:

SMART support is: Available - device has SMART capability.
SMART support is: Enabled

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

General SMART Values:
Offline data collection status: (0x02) Offline data collection activity
                                        was completed without error.
                                        Auto Offline Data Collection: Disabled.
Self-test execution status: ( 0) The previous self-test routine completed
                                        without error or no self-test has ever
                                        been run.
Total time to complete Offline
data collection: ( 5760) seconds.
Offline data collection
capabilities: (0x51) SMART execute Offline immediate.
                                        No Auto Offline data collection support.
                                        Suspend Offline collection upon new
                                        command.
                                        No Offline surface scan supported.
                                        Self-test supported.
                                        No Conveyance Self-test supported.
                                        Selective Self-test supported.
SMART capabilities: (0x0003) Saves SMART data before entering
                                        power-saving mode.
                                        Supports SMART auto save timer.
Error logging capability: (0x01) Error logging supported.
                                        General Purpose Logging supported.
Short self-test routine
recommended polling time: ( 2) minutes.
Extended self-test routine
recommended polling time: ( 60) minutes.
SCT capabilities: (0x703d) SCT Status supported.
                                        SCT Error Recovery Control supported.
                                        SCT Feature Control supported.
                                        SCT Data Table supported.

SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0
  3 Spin_Up_Time 0x0027 164 139 021 Pre-fail Always - 758
  4 Start_Stop_Count 0x0032 095 095 000 Old_age Always - 5330
  5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0
  7 Seek_Error_Rate 0x002f 100 253 051 Pre-fail Always - 0
  9 Power_On_Hours 0x0032 071 071 000 Old_age Always - 21324
 10 Spin_Retry_Count 0x0033 100 100 051 Pre-fail Always - 0
 11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0
 12 Power_Cycle_Count 0x0032 095 095 000 Old_age Always - 5304
183 Runtime_Bad_Block 0x0032 091 091 000 Old_age Always - 9
184 End-to-End_Error 0x0033 100 100 097 Pre-fail Always - 0
187 Reported_Uncorrect 0x0032 100 100 000 Old_age Always - 0
188 Command_Timeout 0x0032 100 097 000 Old_age Always - 43
190 Airflow_Temperature_Cel 0x0022 060 052 040 Old_age Always - 40 (Min/Max 24/41)
191 G-Sense_Error_Rate 0x0032 001 001 000 Old_age Always - 1000
192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 179
193 Load_Cycle_Count 0x0032 148 148 000 Old_age Always - 157315
194 Temperature_Celsius 0x0022 103 095 000 Old_age Always - 40
196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0
200 Multi_Zone_Error_Rate 0x0009 200 200 051 Pre-fail Offline - 0

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ecryptfs-utils 111-0ubuntu1.1
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: KDE
Date: Tue Jul 26 15:02:38 2016
EcryptfsInUse: Yes
InstallationDate: Installed on 2016-05-13 (73 days ago)
InstallationMedia: Kubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
SourcePackage: ecryptfs-utils
UpgradeStatus: No upgrade log present (probably fresh install)