Activation of multiple namespaces simultaneously may lead to an activation failure

This document (7024333) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15 Service Pack 1
IBM POWER9 (ppc64le)
PowerVM

Situation

Activation of a large number of dax/fsdax namespaces simultaneously can fail with error messages similar to the following example:

...
Unable to create mapping for hot added memory <address-start>..<address-end>: -1
dax_pmem: probe of dax1.5 failed with error -14
...

Resolution

Workaround:

1. Instead of activating all the namespaces simultaneously using the command "ndctl enable-namespace all", activate them individually. The following command can be used to activate namespaces individually:

ndctl enable-namespace namespace0.1 ; ndctl enable-namespace namespace0.2 ...

2. Activation of namespaces should be done early in the kernel boot cycle so that enough free slots for namespace bolted entries are available in the lpar hash page table.

Cause

Due to hash-page table limitations the activation of namespace needs to be done early on during boot, there are however a limited number of bolted entries that can be inserted in the primary hash page table of an LPAR.

Additional Information

A kernel fix for this problem has been proposed and may be available in a future kernel releases.

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7024333
  • Creation Date: 10-Dec-2019
  • Modified Date:03-Mar-2020
    • SUSE Linux Enterprise Server

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