Greeting, FYI, we noticed the following commit (built with gcc-9): commit: e9b9734b74656abb585a7f6fabf1d30ce00e51ea ("sched/fair: Reduce cases for active balance") https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master in testcase: boot on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): If you fix the issue, kindly add following tag Reported-by: kernel test robot [ 32.516177][ C1] ================================================================================ [ 32.518142][ C1] UBSAN: shift-out-of-bounds in kernel/sched/fair.c:7741:14 [ 32.519764][ C1] shift exponent 111 is too large for 64-bit type 'long unsigned int' [ 32.521337][ C1] CPU: 1 PID: 337 Comm: (sd-executor) Not tainted 5.11.0-rc2-00009-ge9b9734b7465 #1 [ 32.522980][ C1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 [ 32.528699][ C1] Call Trace: [ 32.529366][ C1] [ 32.529950][ C1] dump_stack+0xac/0xe3 [ 32.530839][ C1] ubsan_epilogue+0xa/0x4e [ 32.531685][ C1] __ubsan_handle_shift_out_of_bounds+0x162/0x17d [ 32.532878][ C1] ? can_migrate_task+0x4f2/0x890 [ 32.533859][ C1] load_balance.cold+0x17/0x25 [ 32.534738][ C1] ? lock_acquire+0xaf/0x400 [ 32.535586][ C1] rebalance_domains+0x351/0x550 [ 32.536587][ C1] __do_softirq+0xd3/0x558 [ 32.537417][ C1] asm_call_irq_on_stack+0xf/0x20 [ 32.538396][ C1] [ 32.539033][ C1] do_softirq_own_stack+0x9d/0xb0 [ 32.539962][ C1] irq_exit_rcu+0xe0/0xf0 [ 32.540798][ C1] sysvec_apic_timer_interrupt+0x71/0xf0 [ 32.541805][ C1] asm_sysvec_apic_timer_interrupt+0x12/0x20 [ 32.542893][ C1] RIP: 0010:__slab_alloc+0x14/0x60 [ 32.543848][ C1] Code: ff ff ff e9 47 fa ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 53 48 83 ec 20 9c 5b fa f6 c7 02 75 0d e8 4e f7 ff ff 53 9d <48> 83 c4 20 5b c3 4c 89 44 24 18 48 89 4c 24 10 89 54 24 0c 89 74 [ 32.547146][ C1] RSP: 0018:ffffc90001cbfbc8 EFLAGS: 00000282 [ 32.548300][ C1] RAX: ffff8881456e27d8 RBX: 0000000000000282 RCX: 0000000000000006 [ 32.549836][ C1] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff813c4939 [ 32.551308][ C1] RBP: ffff8881008b11c0 R08: 0000000000000001 R09: 0000000000000001 [ 32.553506][ C1] R10: 0000000000000001 R11: 0000000000080000 R12: 0000000000000001 [ 32.555016][ C1] R13: 0000000000000000 R14: 0000000000002800 R15: ffffffff8139ae1c [ 32.560568][ C1] ? anon_vma_clone+0x6c/0x2b0 [ 32.561556][ C1] ? __slab_alloc+0x59/0x60 [ 32.562394][ C1] ? anon_vma_clone+0x6c/0x2b0 [ 32.563296][ C1] kmem_cache_alloc+0x33a/0x3c0 [ 32.564252][ C1] anon_vma_clone+0x6c/0x2b0 [ 32.565132][ C1] anon_vma_fork+0x38/0x150 [ 32.565964][ C1] dup_mmap+0x449/0x620 [ 32.566798][ C1] dup_mm+0x63/0x120 [ 32.567639][ C1] copy_process+0x1b7e/0x2050 [ 32.568586][ C1] ? kvm_sched_clock_read+0x14/0x30 [ 32.569524][ C1] ? sched_clock+0x5/0x10 [ 32.570386][ C1] ? sched_clock_cpu+0x11e/0x150 [ 32.571321][ C1] kernel_clone+0xb8/0xa20 [ 32.572206][ C1] ? kvm_sched_clock_read+0x14/0x30 [ 32.573140][ C1] ? sched_clock+0x5/0x10 [ 32.573943][ C1] ? sched_clock_cpu+0x11e/0x150 [ 32.574845][ C1] ? __might_fault+0x47/0xa0 [ 32.575711][ C1] __do_sys_clone+0x66/0x80 [ 32.580655][ C1] do_syscall_64+0x52/0x60 [ 32.581569][ C1] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 32.582621][ C1] RIP: 0033:0x7fa44a0ae7be [ 32.583445][ C1] Code: db 0f 85 25 01 00 00 64 4c 8b 0c 25 10 00 00 00 45 31 c0 4d 8d 91 d0 02 00 00 31 d2 31 f6 bf 11 00 20 01 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 b6 00 00 00 41 89 c4 85 c0 0f 85 c3 00 00 [ 32.586835][ C1] RSP: 002b:00007ffce49cc6f0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 [ 32.588340][ C1] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fa44a0ae7be [ 32.589777][ C1] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 [ 32.591207][ C1] RBP: 0000000000000000 R08: 0000000000000000 R09: 00007fa448f21940 [ 32.592654][ C1] R10: 00007fa448f21c10 R11: 0000000000000246 R12: 0000000000000020 [ 32.594231][ C1] R13: 00007fa449f1741c R14: 00007ffce49cc8b8 R15: 0000000000000001 [ 32.595648][ C1] ================================================================================ To reproduce: # build kernel cd linux cp config-5.11.0-rc2-00009-ge9b9734b7465 .config make HOSTCC=gcc-9 CC=gcc-9 ARCH=x86_64 olddefconfig prepare modules_prepare bzImage 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 --- 0DAY/LKP+ Test Infrastructure Open Source Technology Center https://lists.01.org/hyperkitty/list/lkp@lists.01.org Intel Corporation Thanks, Oliver Sang