FYI, we noticed the following commit (built with gcc-6): commit: 45ac7b432279cfc0731b72a6af07a0e900556156 ("x86/fsgsbase/64: Enable FSGSBASE by default and add a chicken bit") https://github.com/changbae/FSGSBASE fsgs_tip_4.16-rc3_v10.2 in testcase: trinity with following parameters: runtime: 300s test-description: Trinity is a linux system call fuzz tester. test-url: http://codemonkey.org.uk/projects/trinity/ on test machine: qemu-system-x86_64 -enable-kvm -cpu IvyBridge -m 420M caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +-----------------------------------------+------------+------------+ | | c2cd5c4305 | 45ac7b4322 | +-----------------------------------------+------------+------------+ | boot_successes | 8 | 4 | | boot_failures | 0 | 4 | | PANIC:double_fault | 0 | 4 | | RIP:trace_hardirqs_off_caller | 0 | 4 | | RIP:#a3:trace_hardirqs_off_caller | 0 | 4 | | Kernel_panic-not_syncing:Machine_halted | 0 | 4 | +-----------------------------------------+------------+------------+ [ 0.036034] ---------------- [ 0.036566] | NMI testsuite: [ 0.037008] -------------------- [ 0.038017] remote IPI: ok | [ 0.038631] local IPI: [ 0.038654] PANIC: double fault, error_code: 0x0 [ 0.039000] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.16.0-rc3-00014-g45ac7b4 #1 [ 0.039000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 0.039000] RIP: 0010:trace_hardirqs_off_caller+0x0/0x17b [ 0.039000] RSP: 0000:fffffe0000007020 EFLAGS: 00010083 [ 0.039000] RAX: 00000000a2e00a00 RBX: 0000000000000001 RCX: ffffffffa2e00a00 [ 0.039000] RDX: ffff880017600000 RSI: ffffffffffffffff RDI: ffffffffa2e01888 [ 0.039000] RBP: fffffe0000007070 R08: 0000000000000000 R09: 0000000000000000 [ 0.039000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 0.039000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.039000] FS: 0000000000000000(0000) GS:ffff880017600000(0000) knlGS:0000000000000000 [ 0.039000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.039000] CR2: fffffe0000006ff8 CR3: 0000000008a10000 CR4: 00000000001506f0 [ 0.039000] Call Trace: [ 0.039000] <#DF> [ 0.039000] trace_hardirqs_off_thunk+0x1a/0x1c [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] error_entry+0x48/0xd0 [ 0.039000] RIP: 0010:trace_hardirqs_off_caller+0x0/0x17b [ 0.039000] RSP: 0000:fffffe0000007130 EFLAGS: 00010083 ORIG_RAX: 0000000000000000 [ 0.039000] RAX: 00000000a2e00a00 RBX: 0000000000000001 RCX: ffffffffa2e00a00 [ 0.039000] RDX: ffff880017600000 RSI: ffffffffffffffff RDI: ffffffffa2e01888 [ 0.039000] RBP: fffffe0000007180 R08: 0000000000000000 R09: 0000000000000000 [ 0.039000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 0.039000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.039000] ? async_page_fault+0x42/0x80 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] trace_hardirqs_off_thunk+0x1a/0x1c [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] error_entry+0x48/0xd0 [ 0.039000] RIP: 0010:trace_hardirqs_off_caller+0x0/0x17b [ 0.039000] RSP: 0000:fffffe0000007240 EFLAGS: 00010083 ORIG_RAX: 0000000000000000 [ 0.039000] RAX: 00000000a2e00a00 RBX: 0000000000000001 RCX: ffffffffa2e00a00 [ 0.039000] RDX: ffff880017600000 RSI: ffffffffffffffff RDI: ffffffffa2e01888 [ 0.039000] RBP: fffffe0000007290 R08: 0000000000000000 R09: 0000000000000000 [ 0.039000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 0.039000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.039000] ? async_page_fault+0x42/0x80 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] trace_hardirqs_off_thunk+0x1a/0x1c [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] error_entry+0x48/0xd0 [ 0.039000] RIP: 0010:trace_hardirqs_off_caller+0x0/0x17b [ 0.039000] RSP: 0000:fffffe0000007350 EFLAGS: 00010083 ORIG_RAX: 0000000000000000 [ 0.039000] RAX: 00000000a2e00a00 RBX: 0000000000000001 RCX: ffffffffa2e00a00 [ 0.039000] RDX: ffff880017600000 RSI: ffffffffffffffff RDI: ffffffffa2e01888 [ 0.039000] RBP: fffffe00000073a0 R08: 0000000000000000 R09: 0000000000000000 [ 0.039000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 0.039000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.039000] ? async_page_fault+0x42/0x80 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] trace_hardirqs_off_thunk+0x1a/0x1c [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] error_entry+0x48/0xd0 [ 0.039000] RIP: 0010:trace_hardirqs_off_caller+0x0/0x17b [ 0.039000] RSP: 0000:fffffe0000007460 EFLAGS: 00010083 ORIG_RAX: 0000000000000000 [ 0.039000] RAX: 00000000a2e00a00 RBX: 0000000000000001 RCX: ffffffffa2e00a00 [ 0.039000] RDX: ffff880017600000 RSI: ffffffffffffffff RDI: ffffffffa2e01888 [ 0.039000] RBP: fffffe00000074b0 R08: 0000000000000000 R09: 0000000000000000 [ 0.039000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 0.039000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.039000] ? async_page_fault+0x42/0x80 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] trace_hardirqs_off_thunk+0x1a/0x1c [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] error_entry+0x48/0xd0 [ 0.039000] RIP: 0010:trace_hardirqs_off_caller+0x0/0x17b [ 0.039000] RSP: 0000:fffffe0000007570 EFLAGS: 00010083 ORIG_RAX: 0000000000000000 [ 0.039000] RAX: 00000000a2e00a00 RBX: 0000000000000001 RCX: ffffffffa2e00a00 [ 0.039000] RDX: ffff880017600000 RSI: ffffffffffffffff RDI: ffffffffa2e01888 [ 0.039000] RBP: fffffe00000075c0 R08: 0000000000000000 R09: 0000000000000000 [ 0.039000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 0.039000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.039000] ? async_page_fault+0x42/0x80 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] trace_hardirqs_off_thunk+0x1a/0x1c [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] error_entry+0x48/0xd0 [ 0.039000] RIP: 0010:trace_hardirqs_off_caller+0x0/0x17b [ 0.039000] RSP: 0000:fffffe0000007680 EFLAGS: 00010083 ORIG_RAX: 0000000000000000 [ 0.039000] RAX: 00000000a2e00a00 RBX: 0000000000000001 RCX: ffffffffa2e00a00 [ 0.039000] RDX: ffff880017600000 RSI: ffffffffffffffff RDI: ffffffffa2e01888 [ 0.039000] RBP: fffffe00000076d0 R08: 0000000000000000 R09: 0000000000000000 [ 0.039000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 0.039000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.039000] ? async_page_fault+0x42/0x80 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] trace_hardirqs_off_thunk+0x1a/0x1c [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] error_entry+0x48/0xd0 [ 0.039000] RIP: 0010:trace_hardirqs_off_caller+0x0/0x17b [ 0.039000] RSP: 0000:fffffe0000007790 EFLAGS: 00010083 ORIG_RAX: 0000000000000000 [ 0.039000] RAX: 00000000a2e00a00 RBX: 0000000000000001 RCX: ffffffffa2e00a00 [ 0.039000] RDX: ffff880017600000 RSI: ffffffffffffffff RDI: ffffffffa2e01888 [ 0.039000] RBP: fffffe00000077e0 R08: 0000000000000000 R09: 0000000000000000 [ 0.039000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 0.039000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.039000] ? async_page_fault+0x42/0x80 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] trace_hardirqs_off_thunk+0x1a/0x1c [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] error_entry+0x48/0xd0 [ 0.039000] RIP: 0010:trace_hardirqs_off_caller+0x0/0x17b [ 0.039000] RSP: 0000:fffffe00000078a0 EFLAGS: 00010083 ORIG_RAX: 0000000000000000 [ 0.039000] RAX: 00000000a2e00a00 RBX: 0000000000000001 RCX: ffffffffa2e00a00 [ 0.039000] RDX: ffff880017600000 RSI: ffffffffffffffff RDI: ffffffffa2e01888 [ 0.039000] RBP: fffffe00000078f0 R08: 0000000000000000 R09: 0000000000000000 [ 0.039000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 0.039000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.039000] ? async_page_fault+0x42/0x80 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] trace_hardirqs_off_thunk+0x1a/0x1c [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] error_entry+0x48/0xd0 [ 0.039000] RIP: 79a3:trace_hardirqs_off_caller+0x0/0x17b [ 0.039000] RSP: 0000:fffffe0000313762 EFLAGS: 0000000f ORIG_RAX: 0000000000000000 [ 0.039000] RAX: 00000000a2e00a00 RBX: 0000000000000001 RCX: ffffffffa2e00a00 [ 0.039000] RDX: ffff880017600000 RSI: ffffffffffffffff RDI: ffffffffa2e01888 [ 0.039000] RBP: fffffe0000007a00 R08: 0000000000000000 R09: 0000000000000000 [ 0.039000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 0.039000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 0.039000] ? async_page_fault+0x42/0x80 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] ? trace_hardirqs_off_thunk+0x1a/0x1c [ 0.039000] ? vsnprintf+0x368/0x3b5 [ 0.039000] ? vsnprintf+0x368/0x3b5 [ 0.039000] ? sprintf+0x51/0x6d [ 0.039000] ? kallsyms_expand_symbol+0x5/0x73 [ 0.039000] ? __sprint_symbol+0xb0/0xf7 [ 0.039000] ? number+0x149/0x257 [ 0.039000] ? __lock_acquire+0x6a1/0x7c0 [ 0.039000] ? __lock_acquire+0x6a1/0x7c0 [ 0.039000] ? __lock_acquire+0x6a1/0x7c0 [ 0.039000] ? _raw_spin_unlock+0x24/0x2d [ 0.039000] ? __printk_safe_exit+0x5/0xd [ 0.039000] ? console_unlock+0x4c2/0x5a7 [ 0.039000] ? __lock_acquire+0x6a1/0x7c0 [ 0.039000] ? is_bpf_text_address+0x62/0x6a [ 0.039000] ? kernel_text_address+0x6c/0x80 [ 0.039000] ? kernel_text_address+0x6c/0x80 [ 0.039000] ? __kernel_text_address+0xe/0x30 [ 0.039000] ? show_trace_log_lvl+0x1be/0x320 [ 0.039000] ? show_trace_log_lvl+0x1be/0x320 [ 0.039000] ? trace_hardirqs_off+0x167/0x167 [ 0.039000] ? show_regs+0x6a/0x150 [ 0.039000] ? df_debug+0x1d/0x29 [ 0.039000] ? do_double_fault+0x66/0x76 [ 0.039000] ? double_fault+0x53/0x60 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] ? trace_hardirqs_off+0x167/0x167 [ 0.039000] [ 0.039000] WARNING: stack recursion on stack type 5 [ 0.039000] Code: 05 63 30 3b 01 0f 83 22 ff ff ff e9 e2 fe ff ff 83 3d b5 48 3b 01 00 4c 8b 64 24 28 0f 85 2e ff ff ff 5b 5d 41 5c 41 5d 41 5e c3 <65> 8b 05 a6 9f 8e 5d 85 c0 0f 85 6b 01 00 00 41 57 41 56 41 55 [ 0.039000] Kernel panic - not syncing: Machine halted. [ 0.039000] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.16.0-rc3-00014-g45ac7b4 #1 [ 0.039000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 0.039000] Call Trace: [ 0.039000] <#DF> [ 0.039000] dump_stack+0x7d/0xb4 [ 0.039000] panic+0xec/0x23f [ 0.039000] df_debug+0x29/0x29 [ 0.039000] do_double_fault+0x66/0x76 [ 0.039000] double_fault+0x53/0x60 [ 0.039000] WARNING: stack going in the wrong direction? ip=double_fault+0x53/0x60 [ 0.039000] ? restore_regs_and_return_to_kernel+0x21/0x21 [ 0.039000] ? error_entry+0x48/0xd0 [ 0.039000] ? trace_hardirqs_off+0x167/0x167 [ 0.039000] Elapsed time: 10 #!/bin/bash To reproduce: git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp qemu -k job-script # job-script is attached in this email Thanks, lkp