Hi, all I just use ftrace to do some latency study, found that function_graph can not Work, as long as enable it, will cause kernel panic. I searched this online. Found that there are also some cause the same as mine. I am a newer of ftrace. I want to know who know what root cause? Here is some partial log:
echo function_graph > current_tracer [ 9.583813] Unable to handle kernel paging request at virtual address b0200083 [ 9.590997] pgd = c0004000 [ 9.593683] [b0200083] *pgd=00000000 [ 9.597253] Internal error: Oops: 5 [#1] PREEMPT SMP ARM [ 9.602542] Modules linked in: [ 9.605586] CPU: 1 PID: 15 Comm: kworker/1:0 Not tainted 4.0.0-xilinx-00043-gc701690-dirty #515 [ 9.614256] Hardware name: Xilinx Zynq Platform [ 9.618793] Workqueue: 0xe3a00001 ( “å) [ 9.622765] task: df517500 ti: df518000 task.ti: df518000 [ 9.628162] PC is at rb_update_write_stamp+0x18/0xa0 [ 9.633100] LR is at rb_commit+0x34/0xdc [ 9.637005] pc : [<c00b6674>] lr : [<c00b716c>] psr: 60000093 [ 9.637005] sp : df51a0f0 ip : df40b00c fp : df51a104 [ 9.648456] r10: 00000000 r9 : 00000000 r8 : 00bbff80 [ 9.653666] r7 : c0edcf18 r6 : df51a190 r5 : df404100 r4 : df484680 [ 9.660175] r3 : b020006b r2 : df40b000 r1 : df40b2bc r0 : df484680 [ 9.666687] Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment kernel [ 9.674065] Control: 18c5387d Table: 1ee7004a DAC: 00000015 [ 9.679792] Process kworker/1:0 (pid: 15, stack limit = 0xdf518210) [ 9.686041] Stack: (0xdf51a0f0 to 0xdf51a000) [ 9.690411] [<c00b6674>] (rb_update_write_stamp) from [<c00b716c>] (rb_commit+0x34/0xdc) [ 9.698478] [<c00b716c>] (rb_commit) from [<c00b7968>] (ring_buffer_unlock_commit+0x30/0x18c) [ 9.706987] [<c00b7968>] (ring_buffer_unlock_commit) from [<c00beca4>] (__buffer_unlock_commit+0x20/0x28) [ 9.716534] [<c00beca4>] (__buffer_unlock_commit) from [<c00ca094>] (__trace_graph_entry+0x94/0xa8) [ 9.725557] [<c00ca094>] (__trace_graph_entry) from [<c00ca260>] (trace_graph_entry+0x1b8/0x224) [ 9.734323] [<c00ca260>] (trace_graph_entry) from [<c0020824>] (prepare_ftrace_return+0x70/0xac) [ 9.743089] [<c0020824>] (prepare_ftrace_return) from [<c0020404>] (ftrace_graph_caller+0x18/0x20) [ 9.752020] Code: e24cb004 e5903048 e3c1ceff e3cc200f (e5933018) [ 9.758104] ---[ end trace 5781781938261a54 ]--- [ 9.762689] Kernel panic - not syncing: Fatal exception [ 10.933397] SMP: failed to stop secondary CPUs [ 10.937805] ---[ end Kernel panic - not syncing: Fatal exception [ 10.943779] CPU1: stopping [ 10.946471] CPU: 1 PID: 15 Comm: kworker/1:0 Tainted: G D 4.0.0-xilinx-00043-gc701690-dirty #515 [ 10.956358] Hardware name: Xilinx Zynq Platform [ 10.960889] Workqueue: 0xe3a00001 ( “å) [ 10.964896] [<c0021d64>] (unwind_backtrace) from [<c001c1f4>] (show_stack+0x20/0x24) [ 10.972620] [<c001c1f4>] (show_stack) from [<c0592250>] (dump_stack+0x80/0xd0) [ 10.979822] [<c0592250>] (dump_stack) from [<c001efa4>] (ipi_cpu_stop+0x4c/0x80) [ 10.987197] [<c001efa4>] (ipi_cpu_stop) from [<c001f728>] (handle_IPI+0x74/0xbc) [ 10.994573] [<c001f728>] (handle_IPI) from [<c0008720>] (gic_handle_irq+0x68/0x70) [ 11.002123] [<c0008720>] (gic_handle_irq) from [<c001cd84>] (__irq_svc+0x44/0x7c) [ 11.009569] Exception stack(0xdf519e70 to 0xdf519eb8) [ 11.014608] 9e60: 00000034 df518000 00000000 c08d9524 [ 11.022770] 9e80: 00000000 00000000 c00317c8 00000000 c00b6674 00000000 00000008 df519edc [ 11.030929] 9ea0: df519eb8 df519eb8 c058f64c c058f650 60000113 ffffffff [ 11.037541] [<c001cd84>] (__irq_svc) from [<c058f650>] (panic+0x188/0x20c) [ 11.044399] [<c058f650>] (panic) from [<c001c578>] (die+0x380/0x3e0) [ 11.050739] [<c001c578>] (die) from [<c0027c20>] (__do_kernel_fault+0x74/0x94) [ 11.057941] [<c0027c20>] (__do_kernel_fault) from [<c0027f3c>] (do_page_fault+0x2fc/0x31c) [ 11.066185] [<c0027f3c>] (do_page_fault) from [<c0028004>] (do_translation_fault+0x2c/0xc0)
