FYI, we noticed the following commit (built with gcc-6): commit: 9dd6d07682b10a55d1f49d495b85f7b945ff75ca ("[PATCH 10/11] net: dsa: Use PHYLINK for the CPU/DSA ports") url: https://github.com/0day-ci/linux/commits/Ioana-Ciornei/Decoupling-PHYLINK... in testcase: boot on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 2G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +------------------------------------------+------------+------------+ | | 3a2573f868 | 9dd6d07682 | +------------------------------------------+------------+------------+ | boot_successes | 4 | 0 | | boot_failures | 0 | 6 | | kernel_BUG_at_drivers/net/phy/mdio_bus.c | 0 | 6 | | invalid_opcode:#[##] | 0 | 6 | | EIP:mdiobus_free | 0 | 6 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 6 | +------------------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot <rong.a.chen(a)intel.com&gt; [ 39.031781] kernel BUG at drivers/net/phy/mdio_bus.c:503! [ 39.049792] invalid opcode: 0000 [#1] PREEMPT [ 39.058345] CPU: 0 PID: 152 Comm: kworker/0:2 Tainted: G T 5.2.0-rc1-00321-g9dd6d07 #1 [ 39.076106] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 39.091893] Workqueue: events deferred_probe_work_func [ 39.101903] EIP: mdiobus_free+0x21/0x39 [ 39.109323] Code: 18 5f ed ff 5b 5e 5f 5d c3 55 89 e5 52 89 45 fc 8b 45 fc 8b 90 9c 00 00 00 83 fa 01 75 07 e8 9b fa 99 ff eb 1b 83 fa 03 74 02 <0f> 0b c7 80 9c 00 00 00 04 00 00 00 05 a0 00 00 00 e8 94 58 ed ff [ 39.144715] EAX: eff3e008 EBX: eff3a020 ECX: c23a9de9 EDX: 00000002 [ 39.156773] ESI: f0403560 EDI: efffbe24 EBP: efffbdf8 ESP: efffbdf4 [ 39.168825] DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 EFLAGS: 00010297 [ 39.182048] CR0: 80050033 CR2: 00000000 CR3: 02781000 CR4: 000006b0 [ 39.194136] Call Trace: [ 39.198932] _devm_mdiobus_free+0xd/0x10 [ 39.206573] release_nodes+0x194/0x1ad [ 39.213804] devres_release_all+0x37/0x3d [ 39.221709] really_probe+0x2b4/0x3a3 [ 39.228808] driver_probe_device+0x110/0x14b [ 39.237206] __device_attach_driver+0x9d/0xa5 [ 39.245622] bus_for_each_drv+0x65/0x77 [ 39.253081] __device_attach+0x8f/0x104 [ 39.260507] ? driver_allows_async_probing+0x26/0x26 [ 39.270161] device_initial_probe+0x14/0x16 [ 39.278223] bus_probe_device+0x22/0x64 [ 39.285645] deferred_probe_work_func+0x7b/0xa1 [ 39.294428] process_one_work+0x1bc/0x2eb [ 39.302332] ? process_one_work+0x164/0x2eb [ 39.310539] process_scheduled_works+0x1e/0x24 [ 39.319218] worker_thread+0x1cb/0x268 [ 39.326604] kthread+0xeb/0xf0 [ 39.332607] ? process_scheduled_works+0x24/0x24 [ 39.341641] ? __kthread_create_on_node+0x128/0x128 [ 39.350985] ret_from_fork+0x1e/0x28 [ 39.369743] ---[ end trace 2d9c21baf7b99d11 ]--- To reproduce: # build kernel cd linux cp config-5.2.0-rc1-00321-g9dd6d07 .config make HOSTCC=gcc-6 CC=gcc-6 ARCH=i386 olddefconfig make HOSTCC=gcc-6 CC=gcc-6 ARCH=i386 prepare make HOSTCC=gcc-6 CC=gcc-6 ARCH=i386 modules_prepare make HOSTCC=gcc-6 CC=gcc-6 ARCH=i386 SHELL=/bin/bash make HOSTCC=gcc-6 CC=gcc-6 ARCH=i386 bzImage git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email Thanks, Rong Chen