hrtimer: interrupt took 34240 ns rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6937/1:b..l (detected by 0, t=10503 jiffies, g=8537, q=88) task:syz-executor693 state:R running task stack:28448 pid: 6937 ppid: 6547 flags:0x00000000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb44/0x5960 kernel/sched/core.c:6287 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:6687 irqentry_exit+0x31/0x80 kernel/entry/common.c:425 asm_sysvec_reschedule_ipi+0x12/0x20 arch/x86/include/asm/idtentry.h:643 RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:163 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:197 Code: 01 f0 4d 89 03 e9 63 fd ff ff b9 ff ff ff ff ba 08 00 00 00 4d 8b 03 48 0f bd ca 49 8b 45 00 48 63 c9 e9 64 ff ff ff 0f 1f 00 <65> 8b 05 d9 17 8b 7e 89 c1 48 8b 34 24 81 e1 00 01 00 00 65 48 8b RSP: 0018:ffffc9000341f580 EFLAGS: 00000202 RAX: 0000000000000055 RBX: ffffffff899d0040 RCX: 0000000000000005 RDX: 0000000000000000 RSI: ffff888071345580 RDI: 0000000000000003 RBP: ffffc9000341f6a0 R08: ffffffff89e79640 R09: ffffffff83f6c0fa R10: 0000000000000005 R11: 0000000000000075 R12: ffffffff899d0041 R13: ffffffff899d0040 R14: 1ffff92000683eb4 R15: 0000000000000075 format_decode+0x637/0xad0 lib/vsprintf.c:2562 vsnprintf+0x157/0x14f0 lib/vsprintf.c:2749 sprintf+0xc0/0x100 lib/vsprintf.c:2999 proc_self_get_link+0x120/0x1f0 fs/proc/self.c:25 pick_link fs/namei.c:1765 [inline] step_into+0x14e1/0x1c80 fs/namei.c:1826 walk_component+0x171/0x6a0 fs/namei.c:1976 link_path_walk.part.0+0x757/0xd00 fs/namei.c:2297 link_path_walk fs/namei.c:2222 [inline] path_openat+0x265/0x2740 fs/namei.c:3557 do_filp_open+0x1aa/0x400 fs/namei.c:3588 do_sys_openat2+0x16d/0x4d0 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_openat fs/open.c:1232 [inline] __se_sys_openat fs/open.c:1227 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f4a6ad2e9e7 RSP: 002b:00007ffced9fc510 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f4a6ad2e9e7 RDX: 0000000000080001 RSI: 00007f4a6adc3022 RDI: 00000000ffffff9c RBP: 00007f4a6adc3022 R08: 0000000000000000 R09: 00007ffced9fc500 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000080001 R13: 0000000000000000 R14: 00007ffced9fcaf0 R15: 00007ffced9fcab4 rcu: rcu_preempt kthread starved for 10547 jiffies! g8537 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R running task stack:28696 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb44/0x5960 kernel/sched/core.c:6287 schedule+0xd3/0x270 kernel/sched/core.c:6366 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x800 kernel/rcu/tree.c:1957 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2130 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 0 CPU: 0 PID: 6928 Comm: syz-executor693 Not tainted 5.15.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1ae/0x220 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:481 print_other_cpu_stall kernel/rcu/tree_stall.h:586 [inline] check_cpu_stall kernel/rcu/tree_stall.h:729 [inline] rcu_pending kernel/rcu/tree.c:3880 [inline] rcu_sched_clock_irq+0x2125/0x2200 kernel/rcu/tree.c:2599 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1421 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:__schedule+0xb4c/0x5960 kernel/sched/core.c:6166 Code: fa 48 c1 ea 03 80 3c 02 00 0f 85 70 4a 00 00 48 8b bd 40 ff ff ff 4c 89 63 10 4c 89 e6 e8 0c 9c c8 f7 48 89 c7 e8 d4 88 18 f8 <48> 8b b5 e8 fe ff ff 48 b8 00 00 00 00 00 fc ff df 48 c7 04 06 00 RSP: 0018:ffffc9000343f738 EFLAGS: 00000206 RAX: 0000000000f3b0f9 RBX: 0000000000000001 RCX: 1ffffffff1adcad9 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000343f888 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff817d01e8 R11: 0000000000000000 R12: ffff8880b9c32500 R13: 0000000000000000 R14: ffffffff8b332cc0 R15: ffffffff8b332cc0 schedule+0xd3/0x270 kernel/sched/core.c:6366 tty_open+0x885/0x1000 drivers/tty/tty_io.c:2153 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x4c8/0x11d0 fs/open.c:822 do_open fs/namei.c:3428 [inline] path_openat+0x1c9a/0x2740 fs/namei.c:3561 do_filp_open+0x1aa/0x400 fs/namei.c:3588 do_sys_openat2+0x16d/0x4d0 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_openat fs/open.c:1232 [inline] __se_sys_openat fs/open.c:1227 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f4a6ad6dae9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f4a6ad1f318 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f4a6adf53e8 RCX: 00007f4a6ad6dae9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f4a6adf53e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 7974742f7665642f R13: 00007ffced9fca0f R14: 00007f4a6ad1f400 R15: 0000000000022000 sched: RT throttling activated ---------------- Code disassembly (best guess): 0: 01 f0 add %esi,%eax 2: 4d 89 03 mov %r8,(%r11) 5: e9 63 fd ff ff jmpq 0xfffffd6d a: b9 ff ff ff ff mov $0xffffffff,%ecx f: ba 08 00 00 00 mov $0x8,%edx 14: 4d 8b 03 mov (%r11),%r8 17: 48 0f bd ca bsr %rdx,%rcx 1b: 49 8b 45 00 mov 0x0(%r13),%rax 1f: 48 63 c9 movslq %ecx,%rcx 22: e9 64 ff ff ff jmpq 0xffffff8b 27: 0f 1f 00 nopl (%rax) * 2a: 65 8b 05 d9 17 8b 7e mov %gs:0x7e8b17d9(%rip),%eax # 0x7e8b180a <-- trapping instruction 31: 89 c1 mov %eax,%ecx 33: 48 8b 34 24 mov (%rsp),%rsi 37: 81 e1 00 01 00 00 and $0x100,%ecx 3d: 65 gs 3e: 48 rex.W 3f: 8b .byte 0x8b