bisecting fixing commit since 2187f215ebaac73ddbd814696d7c7fa34f0c3de0 building syzkaller on 79b211f74b08737aeb4934c6ff69a263b3c38013 testing commit 2187f215ebaac73ddbd814696d7c7fa34f0c3de0 with gcc (GCC) 8.1.0 kernel signature: 5fdc86762f993cd4d5274cc1bc0b4c1e933463070fdfb70334773d4c4053acff run #0: crashed: INFO: rcu detected stall in do_signal run #1: crashed: INFO: rcu detected stall in do_signal run #2: crashed: INFO: rcu detected stall in do_signal run #3: crashed: INFO: rcu detected stall in bad_area run #4: crashed: INFO: rcu detected stall in do_signal run #5: crashed: INFO: rcu detected stall in bad_area run #6: crashed: INFO: rcu detected stall in corrupted run #7: crashed: INFO: rcu detected stall in do_signal run #8: crashed: INFO: rcu detected stall in bad_area run #9: crashed: INFO: rcu detected stall in bad_area testing current HEAD a10c9c710f9ecea87b9f4bbb837467893b4bef01 testing commit a10c9c710f9ecea87b9f4bbb837467893b4bef01 with gcc (GCC) 8.1.0 kernel signature: 01b10fd5ad7d0da157043c4d82fb7aa93d788088a4b59200b5c2a9c668576f1b run #0: crashed: INFO: rcu detected stall in do_page_fault run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in bad_area run #3: crashed: INFO: rcu detected stall in do_signal run #4: crashed: INFO: rcu detected stall in bad_area run #5: crashed: INFO: rcu detected stall in do_signal run #6: crashed: INFO: rcu detected stall in do_signal run #7: crashed: INFO: rcu detected stall in do_signal run #8: crashed: INFO: rcu detected stall in bad_area run #9: crashed: INFO: rcu detected stall in bad_area revisions tested: 2, total time: 21m51.634870344s (build: 11m18.42968296s, test: 9m48.644822155s) the crash still happens on HEAD commit msg: Merge tag 'for-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power-supply crash: INFO: rcu detected stall in bad_area hrtimer: interrupt took 81937 ns rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=7357, q=668) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294953479-4294942977), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor.2 R running task 28392 8008 7063 0x80000004 Call Trace: sched_show_task.cold.100+0x2ee/0x35d kernel/sched/core.c:5966 print_other_cpu_stall kernel/rcu/tree_stall.h:430 [inline] check_cpu_stall kernel/rcu/tree_stall.h:558 [inline] rcu_pending kernel/rcu/tree.c:3225 [inline] rcu_sched_clock_irq.cold.87+0xaa3/0xc50 kernel/rcu/tree.c:2296 update_process_times+0x23/0x50 kernel/time/timer.c:1727 tick_sched_handle+0x77/0x140 kernel/time/tick-sched.c:176 tick_sched_timer+0x43/0x100 kernel/time/tick-sched.c:1320 __run_hrtimer kernel/time/hrtimer.c:1520 [inline] __hrtimer_run_queues+0x524/0xc00 kernel/time/hrtimer.c:1584 hrtimer_interrupt+0x2df/0x760 kernel/time/hrtimer.c:1646 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 [inline] smp_apic_timer_interrupt+0x163/0x5f0 arch/x86/kernel/apic/apic.c:1138 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:759 [inline] RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0xaa/0xd0 kernel/locking/spinlock.c:191 Code: e0 3e f4 88 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 28 48 83 3d 2d e9 a5 01 00 74 15 48 89 df 57 9d <0f> 1f 44 00 00 eb ad e8 f5 15 b2 f9 eb bb 0f 0b 0f 0b e8 bf 34 53 RSP: 0000:ffffc90009257d00 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: 0000000000000282 RCX: 0000000000000000 RDX: 1ffffffff11e87dc RSI: 0000000000000006 RDI: 0000000000000282 RBP: ffffc90009257d10 R08: 0000000000000006 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88809af30c80 R13: 000000000000000b R14: 0000000000000000 R15: 000000000000000a spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] force_sig_info_to_task+0x259/0x320 kernel/signal.c:1334 force_sig_fault_to_task kernel/signal.c:1676 [inline] force_sig_fault+0xad/0xe0 kernel/signal.c:1683 __bad_area_nosemaphore+0x24d/0x310 arch/x86/mm/fault.c:927 __bad_area arch/x86/mm/fault.c:956 [inline] bad_area+0x64/0x80 arch/x86/mm/fault.c:962 do_user_addr_fault arch/x86/mm/fault.c:1427 [inline] do_page_fault+0xa00/0xe5b arch/x86/mm/fault.c:1535 page_fault+0x39/0x40 arch/x86/entry/entry_64.S:1203 RIP: 0033:0x4057e9 Code: d0 ff ff ff 01 48 8b 7c 24 28 c7 44 24 34 00 00 00 00 e8 4a d3 01 00 85 c0 75 23 48 6b 44 24 20 18 8b 7c 24 1c 48 03 44 24 38 <48> 8b 48 10 48 8b 50 08 48 8b 30 e8 e7 ee 00 00 89 44 24 34 64 f0 RSP: 002b:00007eff6c7d2a70 EFLAGS: 00010202 RAX: 000000002489ed10 RBX: 0000000000000007 RCX: 0000000000414717 RDX: f926d4c288749a1a RSI: 0000000000000000 RDI: 0000000000000004 RBP: 000000000075bf20 R08: 00007eff6c7d2a70 R09: 000000000075bf20 R10: 0000000000000000 R11: 0000000000000000 R12: 00007eff6c7d36d4 R13: 00000000004cae58 R14: 00000000004e4478 R15: 00000000ffffffff rcu: rcu_preempt kthread starved for 10502 jiffies! g7357 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29096 10 2 0x80004000 Call Trace: context_switch kernel/sched/core.c:3378 [inline] __schedule+0x8ae/0x19c0 kernel/sched/core.c:4094 schedule+0xc3/0x2b0 kernel/sched/core.c:4168 schedule_timeout+0x2bd/0x710 kernel/time/timer.c:1898 rcu_gp_fqs_loop kernel/rcu/tree.c:1674 [inline] rcu_gp_kthread+0x9da/0x1a40 kernel/rcu/tree.c:1836 kthread+0x354/0x420 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352