On Fri, 1 Nov 2019 15:08:03 -0600
dann frazier [off-list ref] wrote:

hey,
  fyi, I'm seeing a bunch of errors from tracefs when booting 5.4-rc5 in
lockdown=confidentiality mode:

[    1.763630] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7
[    1.772332] Could not create tracefs 'available_events' entry
[    1.778633] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7
[    1.787095] Could not create tracefs 'set_event' entry
[    1.792412] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7
(...)
[    2.899481] Could not create tracefs 'set_graph_notrace' entry
[    2.905671] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7
[    2.913934] ------------[ cut here ]------------
[    2.918435] Could not register function stat for cpu 0
[    2.923717] WARNING: CPU: 1 PID: 1 at kernel/trace/ftrace.c:987 ftrace_init_tracefs_toplevel+0x168/0x1bc
[    2.933939] Modules linked in:
[    2.937290] CPU: 1 PID: 1 Comm: 

Looks to me that it's working as designed ;-)

I'm guessing we could quiet these warnings for boot up though. :-/

But there should be at least one message that states that the tracefs
files are not being created due to lockdown.

-- Steve