Speaker
Description
For CRIU to successfully checkpoint/restore a process, files must be opened correctly at the correct mounts.
Generally, we get mnt_id for the mount from /proc/<pid>/<fd>/fdinfo and information about the mount from /proc/<pid>/mountinfo.
But, if a file is open on an "unmounted" mount, i.e, a mount has been unmounted using MNT_DETACH (we still have access to fds),
CRIU can't do checkpoint/restore, since it can't get mountinfo for these "unmounted" mounts.
They are not present in /proc/<pid>/mountinfo, and statmount does not work on them.
This talk will discuss potential ways to extract mountinfo for these mounts.
One such approach is to add "unmounted" mounts to a new "umount" mount namespace, along with adding support to statx for exporting mnt_ns_id, which we implemented here:
https://github.com/bsach64/linux/commits/umount-mnt-ns-plus-statx/