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: swapper/0 Not tainted 5.4.0-050400rc5-generic #201910271430 [ 2.946528] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 [ 2.954088] pstate: 60400005 (nZCv daif +PAN -UAO) [ 2.959359] pc : ftrace_init_tracefs_toplevel+0x168/0x1bc [ 2.965262] lr : ftrace_init_tracefs_toplevel+0x168/0x1bc [ 2.971192] sp : ffff80001002bd40 [ 2.974852] x29: ffff80001002bd40 x28: 0000000000000000 [ 2.980680] x27: 0000000000000000 x26: ffff8000119f9358 [ 2.986552] x25: ffff8000119f9580 x24: ffff00007fb77200 [ 2.992359] x23: ffff00007c873e80 x22: ffff80001153d200 [ 2.998201] x21: ffff800010d8ad08 x20: 0000000000000000 [ 3.004007] x19: 0000000000000000 x18: 0000000000000010 [ 3.009851] x17: 0000000000000007 x16: 000000000000000e [ 3.015674] x15: ffff00007d1213e8 x14: ffffffffffffffff [ 3.021526] x13: ffff80009002ba47 x12: ffff80001002ba4f [ 3.027338] x11: ffff800011a1e000 x10: 0000000000000000 [ 3.033148] x9 : ffff800011c13000 x8 : 000000000000015d [ 3.038984] x7 : 0000000000000017 x6 : ffff800011c129c9 [ 3.044783] x5 : 0000000000000007 x4 : 0000000000000000 [ 3.050617] x3 : 0000000000000000 x2 : 00000000ffffffff [ 3.056430] x1 : bcf0a68bd924d700 x0 : 0000000000000000 [ 3.062258] Call trace: [ 3.064951] ftrace_init_tracefs_toplevel+0x168/0x1bc [ 3.070571] tracer_init_tracefs+0xc0/0x1fc [ 3.075165] do_one_initcall+0x50/0x220 [ 3.079384] kernel_init_freeable+0x1ec/0x2b0 [ 3.084186] kernel_init+0x18/0x108 [ 3.088032] ret_from_fork+0x10/0x18 [ 3.091983] ---[ end trace 32f7e54339335d2a ]--- [ 3.097149] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7 [ 3.105311] Could not create tracefs 'tracing_thresh' entry [ 3.110762] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7 [ 3.119199] Could not create tracefs 'README' entry [ 3.124212] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7 [ 3.132920] Could not create tracefs 'saved_cmdlines' entry [ 3.139075] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7 [ 3.147592] Could not create tracefs 'saved_cmdlines_size' entry [ 3.153950] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7 [ 3.162288] Could not create tracefs 'saved_tgids' entry [ 3.206061] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7 [ 3.214629] Could not create tracefs 'dyn_ftrace_total_info' entry [ 3.221063] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7 [ 3.229245] Could not create tracefs 'funcgraph-overrun' entry [ 3.234990] ------------[ cut here ]------------ [ 3.239724] Failed to create trace option: funcgraph-overrun [ 3.239774] WARNING: CPU: 1 PID: 1 at kernel/trace/trace.c:8106 create_trace_option_files+0x200/0x230 [ 3.255931] Modules linked in: [ 3.259332] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W 5.4.0-050400rc5-generic #201910271430 [ 3.270051] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015 [ 3.277621] pstate: 60400005 (nZCv daif +PAN -UAO) [ 3.282902] pc : create_trace_option_files+0x200/0x230 [ 3.288564] lr : create_trace_option_files+0x200/0x230 [ 3.294247] sp : ffff80001002bd10 [ 3.297914] x29: ffff80001002bd10 x28: ffff800011a34508 [ 3.303769] x27: ffff00007cb12e00 x26: ffff800011bb243d [ 3.309638] x25: ffff800010d8b750 x24: ffff00007cb12e00 [ 3.315485] x23: 0000000000000000 x22: ffff800011a34508 [ 3.321327] x21: ffff800011a344d0 x20: 0000000000000000 [ 3.327284] x19: ffff800011a320b8 x18: 0000000000000010 [ 3.333121] x17: 0000000000000007 x16: 000000000000000e [ 3.338980] x15: ffff00007d1213e8 x14: ffffffffffffffff [ 3.344827] x13: ffff80009002b9a7 x12: ffff80001002b9af [ 3.350690] x11: ffff800011a1e000 x10: 0000000000000000 [ 3.356524] x9 : 00000000fffffffe x8 : 6870617267636e75 [ 3.362394] x7 : 66203a6e6f697470 x6 : ffff800011c12498 [ 3.368229] x5 : 0000000000000030 x4 : 0000000000000000 [ 3.374082] x3 : 0000000000000000 x2 : 00000000ffffffff [ 3.379915] x1 : bcf0a68bd924d700 x0 : 0000000000000000 [ 3.385768] Call trace: [ 3.388478] create_trace_option_files+0x200/0x230 [ 3.393849] __update_tracer_options+0x34/0x48 [ 3.398748] tracer_init_tracefs+0x1e0/0x1fc [ 3.403454] do_one_initcall+0x50/0x220 [ 3.407692] kernel_init_freeable+0x1ec/0x2b0 [ 3.412494] kernel_init+0x18/0x108 [ 3.416351] ret_from_fork+0x10/0x18 [ 3.420287] ---[ end trace 32f7e54339335d2b ]--- [ 3.425479] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7 [ 3.433724] Could not create tracefs 'funcgraph-cpu' entry (...) [ 3.692698] Could not create tracefs 'uprobe_events' entry [ 3.698724] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7 [ 3.707217] Could not create tracefs 'uprobe_profile' entry -dann
