FYI, we noticed the following commit (built with gcc-7): commit: 0e27921816ad99f78140e0c61ddf2bc515cc7e22 ("net: dsa: Use PHYLINK for the CPU/DSA ports") https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master 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 SandyBridge -smp 2 -m 2G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +------------------------------------------+------------+------------+ | | 77373d49de | 0e27921816 | +------------------------------------------+------------+------------+ | boot_successes | 14 | 0 | | boot_failures | 1 | 16 | | BUG:kernel_hang_in_boot_stage | 1 | | | kernel_BUG_at_drivers/net/phy/mdio_bus.c | 0 | 16 | | invalid_opcode:#[##] | 0 | 16 | | RIP:mdiobus_free | 0 | 16 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 16 | +------------------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot <rong.a.chen(a)intel.com&gt; [ 30.407329] kernel BUG at drivers/net/phy/mdio_bus.c:503! [ 30.409066] invalid opcode: 0000 [#1] SMP KASAN PTI [ 30.410155] CPU: 1 PID: 114 Comm: kworker/1:1 Tainted: G T 5.2.0-rc1-00391-g0e27921 #1 [ 30.412336] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 [ 30.414226] Workqueue: events deferred_probe_work_func [ 30.415501] RIP: 0010:mdiobus_free+0x4b/0x6f [ 30.416504] Code: 48 89 df 5b 5d 41 5c e9 ec 8b fe fe 31 f6 83 fd 03 48 c7 c7 48 4d 70 90 40 0f 95 c6 31 c9 31 d2 e8 75 bb f1 fe 83 fd 03 74 02 <0f> 0b 4c 89 e7 e8 a3 ba fe fe c7 83 98 00 00 00 04 00 00 00 48 8d [ 30.423831] RSP: 0000:ffff88806995fb88 EFLAGS: 00010297 [ 30.425093] RAX: fffffbfff20e0900 RBX: ffff88806744a940 RCX: ffffffff8b7df4e9 [ 30.426602] RDX: 0000000000000000 RSI: 2000040000000000 RDI: ffffffff90704d68 [ 30.428104] RBP: 0000000000000002 R08: 0000000000000003 R09: 0000000000000007 [ 30.429594] R10: 0000000000000000 R11: ffffffff90501f2b R12: ffff88806744a9d8 [ 30.431080] R13: 0000000000000003 R14: ffff888050801b00 R15: ffff888050801c88 [ 30.432642] FS: 0000000000000000(0000) GS:ffff88806b300000(0000) knlGS:0000000000000000 [ 30.434525] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.435783] CR2: 00000000ffffffff CR3: 000000005c622000 CR4: 00000000000406a0 [ 30.437377] Call Trace: [ 30.437976] release_nodes+0x287/0x2e6 [ 30.438856] ? _raw_spin_lock_irq+0x1c/0x1c [ 30.439782] ? list_move_tail+0x6a/0x6a [ 30.440655] ? __device_links_no_driver+0xad/0xc2 [ 30.441734] really_probe+0x43c/0x637 [ 30.442599] ? driver_allows_async_probing+0x3a/0x3a [ 30.443756] bus_for_each_drv+0xff/0x13c [ 30.444627] ? subsys_find_device_by_id+0x197/0x197 [ 30.445661] ? klist_next+0x12e/0x13e [ 30.446594] __device_attach+0xfe/0x1b7 [ 30.447517] ? device_bind_driver+0x5e/0x5e [ 30.448489] ? ftrace_likely_update+0x23a/0x261 [ 30.449479] bus_probe_device+0x54/0xea [ 30.450406] deferred_probe_work_func+0xf6/0x121 [ 30.451520] process_one_work+0x35a/0x552 [ 30.452460] process_scheduled_works+0x32/0x37 [ 30.453475] worker_thread+0x396/0x4af [ 30.454337] ? process_scheduled_works+0x37/0x37 [ 30.455492] kthread+0x1ca/0x1d9 [ 30.456249] ? __kthread_cancel_work+0xab/0xab [ 30.457278] ret_from_fork+0x24/0x30 [ 30.458149] ---[ end trace fa7633f222494403 ]--- To reproduce: # build kernel cd linux cp config-5.2.0-rc1-00391-g0e27921 .config make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 olddefconfig make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 prepare make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 modules_prepare make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 SHELL=/bin/bash make HOSTCC=gcc-7 CC=gcc-7 ARCH=x86_64 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