bisecting fixing commit since 4fa640dc52302b5e62b01b05c755b055549633ae
building syzkaller on d88894e6773ab63ac8b3f4b2edbae88290aaf0d6
testing commit 4fa640dc52302b5e62b01b05c755b055549633ae with gcc (GCC) 8.1.0
kernel signature: b34f5cc65c4946a17e0b58f3eeee3f02706580446ecada4fd9499399153b7a9f
run #0: crashed: INFO: rcu detected stall in smp_call_function
run #1: crashed: INFO: rcu detected stall in addrconf_dad_work
run #2: crashed: BUG: soft lockup in mutex_spin_on_owner
run #3: crashed: INFO: rcu detected stall in corrupted
run #4: crashed: INFO: rcu detected stall in do_idle
run #5: crashed: INFO: rcu detected stall in corrupted
run #6: crashed: INFO: rcu detected stall in do_idle
run #7: crashed: INFO: rcu detected stall in do_idle
run #8: crashed: INFO: rcu detected stall in do_idle
run #9: crashed: INFO: rcu detected stall in do_idle
testing current HEAD 7cf726a59435301046250c42131554d9ccc566b8
testing commit 7cf726a59435301046250c42131554d9ccc566b8 with gcc (GCC) 8.1.0
kernel signature: c1ef713360328020370a759f6c270c9fde64bfd8c624af36ff745d8ba1017e37
run #0: crashed: INFO: rcu detected stall in wb_workfn
run #1: crashed: INFO: rcu detected stall in do_idle
run #2: crashed: INFO: rcu detected stall in corrupted
run #3: crashed: INFO: rcu detected stall in corrupted
run #4: crashed: INFO: rcu detected stall in do_idle
run #5: crashed: BUG: soft lockup in do_idle
run #6: crashed: INFO: rcu detected stall in corrupted
run #7: crashed: INFO: rcu detected stall in do_idle
run #8: crashed: INFO: rcu detected stall in do_idle
run #9: crashed: INFO: rcu detected stall in do_idle
revisions tested: 2, total time: 26m28.671582939s (build: 11m14.309030468s, test: 14m31.583141856s)
the crash still happens on HEAD
commit msg: Merge tag 'linux-kselftest-kunit-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
crash: INFO: rcu detected stall in do_idle
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-...!: (2 ticks this GP) idle=72e/0/0x1 softirq=9438/9438 fqs=0 
	(t=19142 jiffies g=3749 q=619)
rcu: rcu_preempt kthread starved for 19142 jiffies! g3749 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:14328 pid:   10 ppid:     2 flags:0x00004000
Call Trace:
 context_switch kernel/sched/core.c:3774 [inline]
 __schedule+0x404/0x890 kernel/sched/core.c:4523
 schedule+0x38/0xe0 kernel/sched/core.c:4601
 schedule_timeout+0x1be/0x2e0 kernel/time/timer.c:1881
 rcu_gp_fqs_loop kernel/rcu/tree.c:1925 [inline]
 rcu_gp_kthread+0x707/0xc60 kernel/rcu/tree.c:2099
 kthread+0x148/0x170 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xa3/0xc8 lib/dump_stack.c:118
 nmi_cpu_backtrace.cold.8+0x53/0x6d lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0xd5/0xf0 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:3694 [inline]
 rcu_sched_clock_irq.cold.93+0x61/0x52b kernel/rcu/tree.c:2567
 update_process_times+0x1f/0x60 kernel/time/timer.c:1712
 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+0x1e3/0x4f0 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/0x290 arch/x86/kernel/apic/apic.c:1097
 asm_call_irq_on_stack+0xf/0x20
 </IRQ>
 __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+0xcc/0xf0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: 5b c3 65 48 8b 04 25 c0 7e 01 00 f0 80 48 02 20 48 8b 00 a8 08 75 c3 e9 7c ff ff ff e9 07 00 00 00 0f 00 2d 1c 45 57 00 fb f4 <c3> 90 e9 07 00 00 00 0f 00 2d 0c 45 57 00 f4 c3 cc cc e8 bb 07 ff
RSP: 0018:ffffffff84203e38 EFLAGS: 00000286
RAX: 000000000002e3e5 RBX: ffff8881010cdc00 RCX: 00000000ffffffff
RDX: 0000000000000000 RSI: ffffffff83f25b73 RDI: ffffffff83f6263e
RBP: ffffffff84528660 R08: 0000000000000001 R09: 0000000000000001
R10: ffff88812c02c6c4 R11: ffff88812c02c6a4 R12: 0000000000000001
R13: ffff888130c59864 R14: 0000000000000001 R15: 0000000000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:150 [inline]
 acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
 acpi_idle_do_entry+0x50/0x90 drivers/acpi/processor_idle.c:517
 acpi_idle_enter+0xa0/0xf0 drivers/acpi/processor_idle.c:648
 cpuidle_enter_state+0x94/0x520 drivers/cpuidle/cpuidle.c:237
 cpuidle_enter+0x24/0x40 drivers/cpuidle/cpuidle.c:351
 call_cpuidle kernel/sched/idle.c:132 [inline]
 cpuidle_idle_call kernel/sched/idle.c:213 [inline]
 do_idle+0x2dc/0x350 kernel/sched/idle.c:273
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:369
 start_kernel+0x4eb/0x50a init/main.c:1051
 secondary_startup_64_no_verify+0xa6/0xab
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:rcu_rnp_online_cpus kernel/rcu/tree.c:209 [inline]
RIP: 0010:rcu_lockdep_current_cpu_online+0x42/0x60 kernel/rcu/tree.c:1152
Code: fc 4e 03 85 d2 75 02 5b c3 65 ff 05 28 57 dc 7e e8 23 a9 e4 01 48 c7 c3 40 ec 02 00 89 c0 48 03 1c c5 00 89 0f 84 48 8b 43 18 <48> 8b 40 70 48 85 43 20 0f 95 c0 65 ff 0d fc 56 dc 7e 75 c9 e8 f4
RSP: 0018:ffffc90000d08e58 EFLAGS: 00000082
RAX: ffffffff843d8b40 RBX: ffff88812c12ec40 RCX: 00000000b2001e43
RDX: 0000000000000001 RSI: ffffffff84069579 RDI: ffffffff83eb93c1
RBP: ffffc90000d08f08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff843d8800
R13: ffffffff828aed42 R14: 163f68661388a000 R15: ffff88811ce0e040
FS:  0000000000000000(0000) GS:ffff88812c100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000560d58b56b68 CR3: 000000010f183000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 rcu_read_lock_held_common+0x25/0x40 kernel/rcu/update.c:110
 rcu_read_lock_sched_held+0x1e/0x80 kernel/rcu/update.c:121
 trace_lock_release include/trace/events/lock.h:58 [inline]
 lock_release+0x2e1/0x310 kernel/locking/lockdep.c:5453
 rcu_lock_release include/linux/rcupdate.h:253 [inline]
 rcu_read_unlock include/linux/rcupdate.h:695 [inline]
 advance_sched+0x19a/0x320 net/sched/sch_taprio.c:754
 __run_hrtimer kernel/time/hrtimer.c:1524 [inline]
 __hrtimer_run_queues+0xba/0x4f0 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/0x290 arch/x86/kernel/apic/apic.c:1097
 asm_call_irq_on_stack+0xf/0x20
 </IRQ>
 __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+0xcc/0xf0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: 5b c3 65 48 8b 04 25 c0 7e 01 00 f0 80 48 02 20 48 8b 00 a8 08 75 c3 e9 7c ff ff ff e9 07 00 00 00 0f 00 2d 1c 45 57 00 fb f4 <c3> 90 e9 07 00 00 00 0f 00 2d 0c 45 57 00 f4 c3 cc cc e8 bb 07 ff
RSP: 0018:ffffc90000cd3e68 EFLAGS: 00000286
RAX: 000000000003957b RBX: ffff8881322e6000 RCX: 00000000ffffffff
RDX: 0000000000000000 RSI: ffffffff83f25b73 RDI: ffffffff83f6263e
RBP: ffffffff84528660 R08: 0000000000000001 R09: 0000000000000001
R10: ffff88812c12c6c4 R11: ffff88812c12c6a4 R12: 0000000000000001
R13: ffff888130c59c64 R14: 0000000000000001 R15: 0000000000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:150 [inline]
 acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
 acpi_idle_do_entry+0x50/0x90 drivers/acpi/processor_idle.c:517
 acpi_idle_enter+0xa0/0xf0 drivers/acpi/processor_idle.c:648
 cpuidle_enter_state+0x94/0x520 drivers/cpuidle/cpuidle.c:237
 cpuidle_enter+0x24/0x40 drivers/cpuidle/cpuidle.c:351
 call_cpuidle kernel/sched/idle.c:132 [inline]
 cpuidle_idle_call kernel/sched/idle.c:213 [inline]
 do_idle+0x2dc/0x350 kernel/sched/idle.c:273
 cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:369
 secondary_startup_64_no_verify+0xa6/0xab