Kernel update: Virtuozzo ReadyKernel patch 83.0 for all supported Virtuozzo 7.0 and Virtuozzo Infrastructure Platform kernels

Issue date: 2019-07-12

Applies to: Virtuozzo 7.0, Virtuozzo Infrastructure Platform 2.5, Virtuozzo Infrastructure Platform 3.0

Virtuozzo Advisory ID: VZA-2019-057

1. Overview

The cumulative Virtuozzo ReadyKernel patch was updated with stability fixes. The patch applies to all supported kernels of Virtuozzo 7.0 and Virtuozzo Infrastructure Platform.

2. Bug Fixes

  • [3.10.0-862.9.1.vz7.63.3 to 3.10.0-957.12.2.vz7.86.2] It was found that the in-kernel implementation of Virtuozzo Storage client stored latency values in milliseconds rather than in microseconds, resulting in bogus statistics data. (PSBM-94882)

  • [3.10.0-957.10.1.vz7.85.17 and 3.10.0-957.12.2.vz7.86.2] It was discovered that a race could happen between removal of memcg and workingset_refault() running in parallel. This could result in a kernel crash in memcg_inc_ws_activate(). (PSBM-95700)

  • [All but 3.10.0-957.12.2.vz7.96.17] It was discovered that a node with dozens of CPU cores, lots of RAM and many VMs running could get into a situation when almost all CPU cores were busy in mmu_shrink_scan(). This could happen because memory shrinking was done under kvm_lock spinlock and only for one VM at a time. All CPU cores but one just waited for kvm_lock in such cases, while the last one was busy with the actual memory shrinking for a VM. (PSBM-95077)

  • mem_cgroup_reparent_charges() could get stuck while holding cgroup_mutex and make the whole system hang. (VSTOR-24241)

3. Installing the Update

Download, install, and immediately apply the patch to the current kernel by running ‘readykernel update’.