Greeting, FYI, we noticed the following commit (built with gcc-9): commit: 88d13f778f3a28132b50a0d698a559de695e8a66 ("[PATCH] sched/fair: avoid vruntime compensation for SCHED_IDLE task") url: https://github.com/0day-ci/linux/commits/Jiang-Biao/sched-fair-avoid-vruntime-compensation-for-SCHED_IDLE-task/20200820-200323 base: https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git 5f4a1c4ea44728aa80be21dbf3a0469b5ca81d88 in testcase: boot on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 8G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +----------------------------------------------+------------+------------+ | | 5f4a1c4ea4 | 88d13f778f | +----------------------------------------------+------------+------------+ | boot_successes | 9 | 0 | | boot_failures | 0 | 4 | | WARNING:at_kernel/sched/fair.c:#place_entity | 0 | 4 | | RIP:place_entity | 0 | 4 | +----------------------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot [ 9.183115] WARNING: CPU: 0 PID: 1 at kernel/sched/fair.c:263 place_entity+0x85/0xa0 [ 9.185749] Modules linked in: ip_tables [ 9.186716] CPU: 0 PID: 1 Comm: systemd Not tainted 5.9.0-rc1-00115-g88d13f778f3a28 #1 [ 9.188770] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 [ 9.190637] RIP: 0010:place_entity+0x85/0xa0 [ 9.191717] Code: 48 81 3b 00 00 10 00 75 25 48 01 c5 eb cd 80 3d d8 1b 70 01 00 75 aa 48 c7 c7 06 ba 33 aa c6 05 c8 1b 70 01 01 e8 9d c6 fb ff <0f> 0b eb 93 48 89 da be 00 00 10 00 48 89 c7 e8 47 d3 ff ff eb c9 [ 9.195587] RSP: 0018:ffffa7b180013dd0 EFLAGS: 00010086 [ 9.196787] RAX: 0000000000000000 RBX: ffff9ae9d74f0600 RCX: 0000000000000000 [ 9.198252] RDX: 0000000000000003 RSI: ffffffffaafbecb3 RDI: ffffffffaafbc86c [ 9.199896] RBP: 00000000e79bcfc3 R08: 00000002235af97b R09: 0000000000000013 [ 9.201365] R10: 000000000000072d R11: 0000000000000000 R12: 0000000000000000 [ 9.202843] R13: 0000000000000001 R14: ffff9aea3fc2b300 R15: 0000000000000000 [ 9.204463] FS: 00007f8c948f3940(0000) GS:ffff9aea3fc00000(0000) knlGS:0000000000000000 [ 9.206319] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 9.207669] CR2: 0000558ff0cb9b98 CR3: 000000012f9f0000 CR4: 00000000000006f0 [ 9.209192] Call Trace: [ 9.210687] enqueue_entity+0x218/0x3a0 [ 9.211809] enqueue_task_fair+0x98/0x720 [ 9.212759] sched_move_task+0x184/0x1a0 [ 9.213694] autogroup_move_group+0x97/0x180 [ 9.214682] sched_autogroup_create_attach+0xca/0x1c0 [ 9.215908] ksys_setsid+0xe9/0x120 [ 9.216764] __do_sys_setsid+0xa/0x20 [ 9.217650] do_syscall_64+0x33/0x40 [ 9.218518] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 9.219753] RIP: 0033:0x7f8c95a81797 [ 9.220630] Code: 73 01 c3 48 8b 0d f9 36 0f 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 70 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c9 36 0f 00 f7 d8 64 89 01 48 [ 9.224523] RSP: 002b:00007ffe1ba622a8 EFLAGS: 00000202 ORIG_RAX: 0000000000000070 [ 9.226255] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f8c95a81797 [ 9.227834] RDX: 00000000ffffffff RSI: 00007ffe1ba62260 RDI: 0000000000000000 [ 9.229301] RBP: 0000000000000005 R08: 0000000000000020 R09: 0000000000000000 [ 9.230772] R10: 0000000000000008 R11: 0000000000000202 R12: 00007ffe1ba625d8 [ 9.232371] R13: 0000558ff0cae6d0 R14: 0000000000000000 R15: 0000000000000001 [ 9.233901] ---[ end trace c7ae918a59a4910d ]--- To reproduce: # build kernel cd linux cp config-5.9.0-rc1-00115-g88d13f778f3a28 .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 Thanks, lkp