FYI, we noticed the following commit (built with gcc-7): commit: ac347c1bc840543e1901b84a0edc1effb9ba088c ("[kvm PATCH v6 2/2] kvm: x86: Dynamically allocate guest_fpu") url: https://github.com/0day-ci/linux/commits/Marc-Orr/kvm-x86-Use-task-structs-fpu-field-for-user/20181102-014232 base: https://git.kernel.org/cgit/virt/kvm/kvm.git master in testcase: hackbench with following parameters: nr_threads: 100% mode: process ipc: socket cpufreq_governor: performance test-description: Hackbench is both a benchmark and a stress test for the Linux kernel scheduler. test-url: https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/sched/cfs-scheduler/hackbench.c on test machine: 256 threads Phi with 96G memory caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +-----------------------------------------------------------------+------------+------------+ | | 81c55e1ec7 | ac347c1bc8 | +-----------------------------------------------------------------+------------+------------+ | boot_successes | 2 | 0 | | boot_failures | 12 | 12 | | WARNING:stack_recursion | 12 | 10 | | WARNING:at#for_ip_swapgs_restore_regs_and_return_to_usermode/0x | 7 | 7 | | WARNING:at_ip__slab_free/0x | 12 | 11 | | WARNING:at_ip_fsnotify/0x | 11 | 12 | | WARNING:at#for_ip_interrupt_entry/0x | 4 | 1 | | WARNING:at_mm/slab_common.c:#kmem_cache_create_usercopy | 0 | 12 | | RIP:kmem_cache_create_usercopy | 0 | 11 | +-----------------------------------------------------------------+------------+------------+ [ 35.878475] WARNING: CPU: 35 PID: 9831 at mm/slab_common.c:473 kmem_cache_create_usercopy+0xbe/0x1c9 [ 35.891008] Modules linked in: kvm_intel(+) kvm irqbypass sg ipmi_si(+) ipmi_msghandler [ 35.900734] CPU: 35 PID: 9831 Comm: systemd-udevd Not tainted 4.19.0-rc4-00223-gac347c1 #1 [ 35.900737] Hardware name: Intel Corp. GROVEPORT/GROVEPORT, BIOS GVPRCRB1.86B.0010.R02.1606082342 06/08/2016 Startin [ 35.900744] RIP: 0010:kmem_cache_create_usercopy+0xbe/0x1c9 g LSB: Execute t [ 35.900757] Code: 00 41 81 e4 00 6d af 04 45 85 ff 75 09 45 85 f6 74 04 0f 0b eb 16 45 39 fd 72 0f 44 89 e8 44 29 f8 44 39 f0 0f 83 ee 00 00 00 <0f> 0b 45 31 f6 4c 8b 44 24 48 8b 54 24 08 44 89 e1 44 89 ee 48 89 he kexec -e command to reboot sy [ 35.953886] RSP: 0018:ffffc900097efc08 EFLAGS: 00010287 stem... [ 35.958318] ipmi_si IPI0001:00: Found new BMC (man_id: 0x000157, prod_id: 0x0075, dev_id: 0x21) [ 35.961539] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000004000000 [ 35.961543] RDX: ffff8817d56faa00 RSI: 0000000000000020 RDI: ffffffffa00d2cda [ 35.961546] RBP: ffffffffa00d2cda R08: 0000000000000040 R09: 0000000000000a80 [ 35.961548] R10: ffffea005f482480 R11: ffffffff82057dad R12: 0000000004000000 [ 35.961551] R13: 0000000000000a80 R14: 0000000000000040 R15: 0000000000000a80 [ 35.961561] FS: 00007f401a32f8c0(0000) GS:ffff8817dc4c0000(0000) knlGS:0000000000000000 [ 35.993052] ipmi_si IPI0001:00: IPMI kcs interface initialized [ 35.998121] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 35.998125] CR2: 00007f401a32e036 CR3: 000000179e360000 CR4: 00000000001406e0 [ 35.998128] Call Trace: [ 35.998178] kvm_arch_init+0x87/0x1a8 [kvm] [ 35.998212] kvm_init+0x2d/0x263 [kvm] [ 36.059761] ? hardware_setup+0x675/0x675 [kvm_intel] [ 36.059784] vmx_init+0x24/0x431 [kvm_intel] 0m] Started Regu [ 36.078359] do_one_initcall+0x97/0x196 lar background p [ 36.084195] ? _cond_resched+0x25/0x29 rogram processin [ 36.089931] ? kmem_cache_alloc_trace+0x4f/0x18b g daemon. [ 36.096641] do_init_module+0x5b/0x1eb [ 36.101878] load_module+0x1a69/0x2073 [ 36.106488] ? vfs_read+0x10b/0x137 [ 36.110802] ? vfs_read+0x10b/0x137 [ 36.123316] ? __se_sys_finit_module+0x91/0xb7 [ 36.123321] __se_sys_finit_module+0x91/0xb7 Startin [ 36.123328] do_syscall_64+0x55/0xe4 g Login Service. [ 36.123343] entry_SYSCALL_64_after_hwframe+0x44/0xa9 .. [ 36.146797] RIP: 0033:0x7f40191ac229 [ 36.151207] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 3f 4c 2b 00 f7 d8 64 89 01 48 [ 36.173304] RSP: 002b:00007ffe87e4f9e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 [ 36.182535] RAX: ffffffffffffffda RBX: 00005578f2ff7350 RCX: 00007f40191ac229 [ 36.182538] RDX: 0000000000000000 RSI: 00007f4019ac5265 RDI: 0000000000000007 [ 36.182540] RBP: 00007f4019ac5265 R08: 0000000000000000 R09: 00007ffe87e4ff60 [ 36.182542] R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000000000 [ 36.182545] R13: 00005578f2ff7c70 R14: 0000000000020000 R15: 00005578f2fbecbc [ 36.182553] ---[ end trace 4d81db4be3642e75 ]--- To reproduce: git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp install job.yaml # job file is attached in this email bin/lkp run job.yaml Thanks, Rong Chen