bisecting fixing commit since d573e8a79f70404ba08623d1de7ea617d55092ac building syzkaller on d96e88f3207d7ac7ad65e13b896f702ad04c46f7 testing commit d573e8a79f70404ba08623d1de7ea617d55092ac with gcc (GCC) 8.1.0 kernel signature: 2ab6cda73bcf2ec2c1b3f535db71fb8efc5b4d33f8c440cc3d71ee69e56fc211 run #0: crashed: INFO: rcu detected stall in pie_timer run #1: crashed: INFO: rcu detected stall in corrupted run #2: crashed: INFO: rcu detected stall in run_timer_softirq run #3: crashed: INFO: rcu detected stall in lock_is_held_type run #4: crashed: INFO: rcu detected stall in pie_timer run #5: crashed: INFO: rcu detected stall in debug_smp_processor_id run #6: crashed: INFO: rcu detected stall in run_timer_softirq run #7: crashed: INFO: rcu detected stall in run_timer_softirq run #8: crashed: INFO: rcu detected stall in run_timer_softirq run #9: crashed: INFO: rcu detected stall in run_timer_softirq testing current HEAD 106fa147d3daa58d2c1ae5f41a29d07036fe7d0a testing commit 106fa147d3daa58d2c1ae5f41a29d07036fe7d0a with gcc (GCC) 8.1.0 kernel signature: a9966a6c55ebcabd65b04c9263e44205bac4fb454cfa737e2b00b507210b7df3 run #0: crashed: INFO: rcu detected stall in call_timer_fn run #1: crashed: INFO: rcu detected stall in call_timer_fn run #2: crashed: INFO: rcu detected stall in run_timer_softirq run #3: crashed: INFO: rcu detected stall in pie_timer run #4: crashed: INFO: rcu detected stall in pie_timer run #5: crashed: INFO: rcu detected stall in run_timer_softirq run #6: crashed: INFO: rcu detected stall in call_timer_fn run #7: crashed: INFO: rcu detected stall in pie_timer run #8: crashed: INFO: rcu detected stall in lock_is_held_type run #9: crashed: INFO: rcu detected stall in run_timer_softirq revisions tested: 2, total time: 33m9.579420119s (build: 17m1.535023569s, test: 15m15.797237457s) the crash still happens on HEAD commit msg: Linux 4.19.127 crash: INFO: rcu detected stall in run_timer_softirq rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-....: (1 GPs behind) idle=f2a/1/0x4000000000000004 softirq=31599/31601 fqs=5247 rcu: (t=10500 jiffies g=23285 q=1536) NMI backtrace for cpu 0 CPU: 0 PID: 30871 Comm: syz-executor.5 Not tainted 4.19.127-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+0x123/0x177 lib/dump_stack.c:118 nmi_cpu_backtrace.cold.4+0x3e/0x76 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xe6/0x11a lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_dump_cpu_stacks+0x175/0x1c2 kernel/rcu/tree.c:1340 print_cpu_stall kernel/rcu/tree.c:1478 [inline] check_cpu_stall kernel/rcu/tree.c:1550 [inline] __rcu_pending kernel/rcu/tree.c:3293 [inline] rcu_pending kernel/rcu/tree.c:3336 [inline] rcu_check_callbacks.cold.81+0x5cc/0xd67 kernel/rcu/tree.c:2682 update_process_times+0x2a/0x60 kernel/time/timer.c:1638 tick_sched_handle+0x77/0x140 kernel/time/tick-sched.c:168 tick_sched_timer+0x37/0xf0 kernel/time/tick-sched.c:1278 __run_hrtimer kernel/time/hrtimer.c:1401 [inline] __hrtimer_run_queues+0x2f7/0xab0 kernel/time/hrtimer.c:1463 hrtimer_interrupt+0x2df/0x760 kernel/time/hrtimer.c:1521 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1067 [inline] smp_apic_timer_interrupt+0x114/0x540 arch/x86/kernel/apic/apic.c:1092 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] RIP: 0010:_raw_spin_unlock_irq+0x56/0x80 kernel/locking/spinlock.c:192 Code: 12 88 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 32 48 83 3d 3b 42 90 01 00 74 1f fb 66 0f 1f 44 00 00 01 00 00 00 e8 50 eb c0 fa 65 8b 05 59 29 80 79 85 c0 74 05 5b RSP: 0018:ffff8880aea07de0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: ffff8880aea23a00 RCX: 1ffff1100ce46db2 RDX: 1ffffffff10240d3 RSI: ffff888067236d70 RDI: ffffffff88120698 RBP: ffff8880aea07de8 R08: ffff888067236d90 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880aea07e60 R13: dffffc0000000000 R14: ffffffff8535b2e0 R15: ffff8880aea23a00 expire_timers kernel/time/timer.c:1362 [inline] __run_timers kernel/time/timer.c:1684 [inline] run_timer_softirq+0xb58/0x1180 kernel/time/timer.c:1697 __do_softirq+0x260/0x92d kernel/softirq.c:292 invoke_softirq kernel/softirq.c:372 [inline] irq_exit+0x17f/0x1c0 kernel/softirq.c:412 exiting_irq arch/x86/include/asm/apic.h:544 [inline] smp_apic_timer_interrupt+0x13e/0x540 arch/x86/kernel/apic/apic.c:1094 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:789 [inline] RIP: 0010:generic_exec_single+0x281/0x390 kernel/smp.c:154 Code: 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 ef 00 00 00 48 83 3d 22 65 b9 06 00 0f 84 8e 00 00 00 48 89 df 57 9d <0f> 1f 44 00 00 31 d2 e9 7d fe ff ff 4c 89 e7 e8 ab e2 38 00 e9 a4 RSP: 0018:ffff888063947aa8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 RAX: dffffc0000000000 RBX: 0000000000000286 RCX: 1ffff1100ce46db2 RDX: 1ffffffff10240d1 RSI: ffff888067236d70 RDI: 0000000000000286 RBP: ffff888063947ad0 R08: ffff888067236d90 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff888063947b38 R13: ffff888063947be0 R14: ffffffff81742d60 R15: 0000000000000001 smp_call_function_single+0xe5/0x370 kernel/smp.c:299 task_function_call+0xd0/0x130 kernel/events/core.c:115 perf_install_in_context+0x1ca/0x310 kernel/events/core.c:2616 __do_sys_perf_event_open+0x13fa/0x20d0 kernel/events/core.c:10895 __se_sys_perf_event_open kernel/events/core.c:10520 [inline] __x64_sys_perf_event_open+0xb9/0x140 kernel/events/core.c:10520 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x459a09 Code: fd b7 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fd77b114c78 EFLAGS: 00000246 ORIG_RAX: 000000000000012a RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459a09 RDX: ffffffffffffffff RSI: 0000000000000000 RDI: 000000002001d000 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 00007fd77b1156d4 R13: 00000000004c6855 R14: 00000000004dba68 R15: 00000000ffffffff