Server shutdown takes a very long time

This document (7022298) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 12 Service Pack 2 (SLES 12 SP2)
SUSE Linux Enterprise Server 12 Service Pack 3 (SLES 12 SP3)

Situation

On servers with a large number of mount points (inc.autofs configured mount points), the server can take a very long time to shutdown. High CPU utilization can also occur during the shutdown process.

The problem is not seen if the server is restricted to access only one CPU.

Resolution

A kernel patch has been created for this issue and will be released in a maintenance kernel in the near future. Meanwhile, if this error is encountered and a patch is required, please contact SUSE Customer Care quoting this document.

Cause

The use of the 'synchronize_rcu()' function during the shutdown process causes unacceptable delays on multi-processor boxes where many mount points are in use or defined.

Additional Information

The mentioned kernel patch, replaces the 'synchronize_rcu()' call with 'synchronize_rcu_expedited()'.

In customer testing, this patch has been shown to reduce a 6 minute shutdown time to approx. 17 seconds.

A support agreement is needed in order to obtain the patch mentioned in this document.

Disclaimer

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