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== Requirements ==
== Requirements ==
AutoFS migration is supported by CRIU starting from version ...
Another requirement is linux kernel with version 4.6 or higher.
Another requirement is linux kernel with version 4.6 or higher.
Howewer, there is a limitation in migrating of systemd services, using AutoFS.
Howewer, there is a limitation in migrating of systemd services, using AutoFS.
The problem is that systemd saves AutoFS mount point device ID in its internals and compares saved value with current one on each autofs-related request from kernel side.
The root of the limitation is that systemd saves AutoFS mount point device ID in its internals and compares saved value with current one on each AutoFS-related request from kernel side, and if they do not match - ignores the request.
CRIU reconstructs AutoFS mount point on restore with different device ID, thus systemd doesn't recognize it anymore.
In user world it means, that any access to AutoFS mount point, served by systemd, will hung. Restart of the service solves this issue.
== Tricks ==
To overcome the limitation above, <code>systemd-autofs-restart.sh</code> action script was introduced. It can be found in <code>scripts</code> directory in CRIU sources.
This script is aimed to be used with CRIU option <code>--action-script</code> on restore to fix the issue for those systemd services, which can be painlessly restarted.
It restarts only one service so far: <code>proc-sys-fs-binfmt_misc.automount</code>. But it can be easily to support any other.
[[Category:HOWTO]]
[[Category:HOWTO]]