Kernel message unregister_netdevice: waiting for <device_name> to become free. Usage count = <number>

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Article ID: 168084

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Updated On:

Products

XOS

Issue/Introduction

Shows the workaround and the solution for the following message reported by kernel: unregister_netdevice: waiting for to become free. Usage count =
  • Cannot delete VS via SmartDashboard; An error occurs and SmartDashboard is disconnected.
  • The message kernel: unregister_netdevice: waiting for <device_name> to become free. Usage count = <number> is displayed.

Cause

This issue is mostly seen on systems where VPN is used on the VS which has been deleted/taken down. This problem has also been observed on Check Point SPLAT.




Resolution

Check Point has fixed this problem in Check Point R70.
The VSX NGX R65 installation script in XOS 8.1.4 or XOS 8.5.3 or later will automatically add the following to /etc/sysctl.conf:

net.core.netdev_unregister_max = 5

Workaround

Workaround for Check Point R65 and R70 before applying fix:
The workaround is to set the following kernel parameter during runtime:

echo n > /proc/sys/net/core/netdev_unregister_max
or
sysctl -w net.core.netdev_unregister_max=n

To keep the setting persistent over a reboot, edit /etc/sysctl.conf for the VAP in question and set the line as follows:
net.core.netdev_unregister_max=n

Where n is the number of times the kernel will check if the net device was unregistered before moving on. This should be set to number bigger than what is reported in the kernel message "unregister_netdevice: ... Usage count = <number>". Check Point recommends the value be set to 5. The default value is 0.