bisecting fixing commit since 7cc2a8ea104820dd9e702202621e8fd4d9f6c8cf building syzkaller on 510951950dc0ee69cfdaf746061d3dbe31b49fd8 testing commit 7cc2a8ea104820dd9e702202621e8fd4d9f6c8cf with gcc (GCC) 8.1.0 kernel signature: 8b2468476f9735981163d21526ae2e3cda35b403e4a89b30e8aaf34c21926fd2 run #0: crashed: INFO: rcu detected stall in sys_clock_settime run #1: crashed: INFO: rcu detected stall in sys_fallocate run #2: crashed: INFO: rcu detected stall in sys_clock_settime run #3: crashed: INFO: rcu detected stall in sys_clock_settime run #4: crashed: INFO: rcu detected stall in sys_clock_settime run #5: crashed: INFO: rcu detected stall in try_check_zero run #6: crashed: INFO: rcu detected stall in batadv_nc_worker run #7: crashed: INFO: rcu detected stall in sys_clock_settime run #8: crashed: INFO: rcu detected stall in sys_clock_settime run #9: crashed: INFO: rcu detected stall in sys_clock_settime testing current HEAD 583090b1b8232e6eae243a9009699666153a13a9 testing commit 583090b1b8232e6eae243a9009699666153a13a9 with gcc (GCC) 8.1.0 kernel signature: bce67bc80c852fda0e271b1e6268e18ff7f6af98b1344c452831d809edefb703 run #0: crashed: INFO: rcu detected stall in corrupted run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in __sys_sendmsg run #3: crashed: INFO: rcu detected stall in do_idle run #4: crashed: INFO: rcu detected stall in shmem_fault run #5: crashed: BUG: soft lockup in smp_call_function run #6: crashed: BUG: soft lockup in smp_call_function run #7: crashed: BUG: soft lockup in smp_call_function run #8: crashed: INFO: rcu detected stall in smp_call_function run #9: crashed: INFO: rcu detected stall in sys_clock_settime revisions tested: 2, total time: 23m47.462824476s (build: 9m55.216280956s, test: 13m21.339082942s) the crash still happens on HEAD commit msg: Merge tag 'block5.9-2020-10-08' of git://git.kernel.dk/linux-block crash: INFO: rcu detected stall in sys_clock_settime rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (1 ticks this GP) idle=4a6/1/0x4000000000000000 softirq=9534/9534 fqs=0 (t=27132 jiffies g=3741 q=4119) rcu: rcu_preempt kthread starved for 27132 jiffies! g3741 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:I stack:14648 pid: 10 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:3778 [inline] __schedule+0x404/0x8a0 kernel/sched/core.c:4527 schedule+0x37/0xe0 kernel/sched/core.c:4602 schedule_timeout+0x1af/0x2d0 kernel/time/timer.c:1879 rcu_gp_fqs_loop kernel/rcu/tree.c:1890 [inline] rcu_gp_kthread+0x707/0xc60 kernel/rcu/tree.c:2060 kthread+0x148/0x170 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 NMI backtrace for cpu 0 CPU: 0 PID: 8177 Comm: syz-executor.3 Not tainted 5.9.0-rc8-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xa3/0xcc lib/dump_stack.c:118 nmi_cpu_backtrace.cold.8+0x3e/0x58 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xd5/0xec lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0xa2/0xce kernel/rcu/tree_stall.h:318 print_cpu_stall kernel/rcu/tree_stall.h:551 [inline] check_cpu_stall kernel/rcu/tree_stall.h:625 [inline] rcu_pending kernel/rcu/tree.c:3639 [inline] rcu_sched_clock_irq.cold.94+0x61/0x52d kernel/rcu/tree.c:2521 update_process_times+0x1f/0x60 kernel/time/timer.c:1710 tick_sched_handle.isra.24+0x1a/0x50 kernel/time/tick-sched.c:176 tick_sched_timer+0x6c/0x80 kernel/time/tick-sched.c:1328 __run_hrtimer kernel/time/hrtimer.c:1524 [inline] __hrtimer_run_queues+0x1e1/0x510 kernel/time/hrtimer.c:1588 hrtimer_interrupt+0xf9/0x210 kernel/time/hrtimer.c:1650 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline] __sysvec_apic_timer_interrupt+0x8e/0x2b0 arch/x86/kernel/apic/apic.c:1097 asm_call_irq_on_stack+0xf/0x20 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline] run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline] sysvec_apic_timer_interrupt+0xc1/0xe0 arch/x86/kernel/apic/apic.c:1091 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:581 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:770 [inline] RIP: 0010:on_each_cpu+0x61/0xa0 kernel/smp.c:701 Code: c4 04 04 03 00 48 89 c3 74 52 fa 66 0f 1f 44 00 00 f6 c7 02 75 33 4c 89 e7 ff d5 48 83 3d 9e 04 04 03 00 74 39 48 89 df 57 9d <0f> 1f 44 00 00 bf 01 00 00 00 e8 d0 60 f7 ff 65 8b 05 19 e5 d8 7e RSP: 0018:ffffc90002f9fe98 EFLAGS: 00000286 RAX: 000000000000007f RBX: 0000000000000286 RCX: 0000000000000002 RDX: 0000000000000000 RSI: ffffffff83ed46f3 RDI: 0000000000000286 RBP: ffffffff8126e490 R08: 0000000000000001 R09: 0000000000000001 R10: ffff88810ee22380 R11: 41088e48081454d1 R12: 0000000000000000 R13: 0000000017b52ec7 R14: ffffffffe97185a9 R15: 0000000000000286 clock_was_set+0x13/0x20 kernel/time/hrtimer.c:876 do_settimeofday64+0x179/0x210 kernel/time/timekeeping.c:1260 __do_sys_clock_settime kernel/time/posix-timers.c:1079 [inline] __se_sys_clock_settime kernel/time/posix-timers.c:1067 [inline] __x64_sys_clock_settime+0x64/0xb0 kernel/time/posix-timers.c:1067 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45cba9 Code: 8d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 5b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f77423fec78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3 RAX: ffffffffffffffda RBX: 00000000004db5e0 RCX: 000000000045cba9 RDX: 0000000000000000 RSI: 0000000020000400 RDI: 0000000000000000 RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000007b R14: 00000000004c352c R15: 00007f77423ff6d4