FYI, we noticed the following commit: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/debug commit f334c060d49fea9115806387c93035d33bf27db5 ("sched/core: Add debug code to catch missing update_rq_clock()") in testcase: boot on test machine: qemu-system-x86_64 -enable-kvm -smp 2 -m 512M caused below changes: +------------------------------------------------+------------+------------+ | | c0e7629f33 | f334c060d4 | +------------------------------------------------+------------+------------+ | boot_successes | 0 | 0 | | boot_failures | 26 | 26 | | IP-Config:Auto-configuration_of_network_failed | 26 | 24 | | WARNING:at_kernel/sched/sched.h:#rq_clock_task | 0 | 26 | | calltrace:_do_fork | 0 | 26 | | BUG:kernel_hang_in_test_stage | 0 | 2 | +------------------------------------------------+------------+------------+ [ 0.274186] Last level dTLB entries: 4KB 0, 2MB 0, 4MB 0, 1GB 0 [ 0.275175] debug: unmapping init [mem 0xffffffff826bb000-0xffffffff826c2fff] [ 0.278009] ------------[ cut here ]------------ [ 0.278734] WARNING: CPU: 0 PID: 0 at kernel/sched/sched.h:797 rq_clock_task+0x60/0x6a [ 0.280211] rq->clock_update_flags < RQCF_ACT_SKIP [ 0.280947] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.8.0-00074-gf334c06 #1 [ 0.282048] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 0.283362] 0000000000000000 ffffffff82203d60 ffffffff814ab000 ffffffff82203db0 [ 0.284541] 0000000000000000 ffffffff82203da0 ffffffff810dbc43 0000031d82203e18 [ 0.285718] ffff88001e1d6000 0000000000000200 ffff88001e1d6098 0000000000000000 [ 0.286930] Call Trace: [ 0.287306] [<ffffffff814ab000>] dump_stack+0x82/0xb8 [ 0.288079] [<ffffffff810dbc43>] __warn+0xb3/0xce [ 0.288795] [<ffffffff810dbca4>] warn_slowpath_fmt+0x46/0x4e [ 0.289640] [<ffffffff810ff796>] rq_clock_task+0x60/0x6a [ 0.290482] [<ffffffff81102a05>] post_init_entity_util_avg+0x3a/0xdb [ 0.291437] [<ffffffff810fa4cb>] wake_up_new_task+0x6f/0xd9 [ 0.292280] [<ffffffff810db43a>] _do_fork+0x16b/0x263 [ 0.293054] [<ffffffff815409a1>] ? acpi_hw_register_read+0x65/0xcb [ 0.294007] [<ffffffff81541194>] ? acpi_read_bit_register+0x29/0x44 [ 0.294953] [<ffffffff810f7ab7>] ? cpumask_next+0x2c/0x31 [ 0.295772] [<ffffffff810db556>] kernel_thread+0x24/0x26 [ 0.296567] [<ffffffff81ae6416>] rest_init+0x1d/0x131 [ 0.297343] [<ffffffff825a8f03>] start_kernel+0x3e4/0x3f1 [ 0.298192] [<ffffffff825a8120>] ? early_idt_handler_array+0x120/0x120 [ 0.299173] [<ffffffff825a8299>] x86_64_start_reservations+0x2a/0x2c [ 0.300130] [<ffffffff825a8386>] x86_64_start_kernel+0xeb/0xf8 [ 0.301023] ---[ end trace 0000000000000000 ]--- [ 0.301908] smpboot: APIC(0) Converting physical 0 to logical package 0 Thanks, Kernel Test Robot