[$] Dynamically allocated pseudo-filesystems

It is perhaps unusual to have a kernel tracing developer leading a
filesystem session, Steven Rostedt said, at the beginning of such a session at the
2022 Linux Storage,
Filesystem, Memory-management and BPF Summit (LSFMM). But he was doing
so to
try to find a good way to dynamically allocate kernel data structures
for some of the pseudo-filesystems, such as sysfs, debugfs, and tracefs,
in the kernel.
Avoiding static allocations would save memory, especially on systems
that are not actually using any of the files in those filesystems.