rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (10499 ticks this GP) idle=8c3/1/0x4000000000000000 softirq=63618/63618 fqs=0 (t=10500 jiffies g=97877 q=31) rcu: rcu_preempt kthread starved for 10500 jiffies! g97877 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 28532 Comm: syz-executor.4 Not tainted 5.15.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__schedule+0x1/0x5960 kernel/sched/core.c:6166 Code: 5d 41 5c c3 e8 90 90 86 f8 eb d9 e8 89 90 86 f8 e9 4b ff ff ff e8 1f 90 86 f8 e9 02 ff ff ff e8 35 90 86 f8 e9 6c ff ff ff 55 <48> 89 e5 41 57 48 8d 85 78 ff ff ff 41 56 48 c1 e8 03 41 55 41 54 RSP: 0018:ffffc9000679f888 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffff88802b9a9c80 RCX: 1ffffffff2049b34 RDX: 1ffff11005735613 RSI: ffffffff842f7930 RDI: 0000000000000000 RBP: ffff88802b9a9c80 R08: 0000000000000000 R09: ffff88802b9a9c87 R10: ffffffff842f7922 R11: 0000000000000000 R12: ffff88802b9a9cac R13: ffffed1005735390 R14: dffffc0000000000 R15: ffff88802ff98f00 FS: 00007f6ae0bb6700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000560ba22bb218 CR3: 0000000083ea5000 CR4: 0000000000350ee0 Call Trace: 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: 0033:0x7f6ae3640a39 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f6ae0bb6188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f6ae3743f60 RCX: 00007f6ae3640a39 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f6ae369ae8f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff1a61e05f R14: 00007f6ae0bb6300 R15: 0000000000022000 NMI backtrace for cpu 0 CPU: 0 PID: 28529 Comm: syz-executor.0 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_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:343 print_cpu_stall kernel/rcu/tree_stall.h:627 [inline] check_cpu_stall kernel/rcu/tree_stall.h:711 [inline] rcu_pending kernel/rcu/tree.c:3880 [inline] rcu_sched_clock_irq.cold+0x9d/0x746 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:ffffc9000612f738 EFLAGS: 00000206 RAX: 0000000000eb0ec3 RBX: 0000000000000001 RCX: 1ffffffff1adcad9 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000612f888 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: 0033:0x7f04db0e4a39 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f04d865a188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f04db1e7f60 RCX: 00007f04db0e4a39 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f04db13ee8f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffe0db97cdf R14: 00007f04d865a300 R15: 0000000000022000 sched: RT throttling activated ---------------- Code disassembly (best guess): 0: 5d pop %rbp 1: 41 5c pop %r12 3: c3 retq 4: e8 90 90 86 f8 callq 0xf8869099 9: eb d9 jmp 0xffffffe4 b: e8 89 90 86 f8 callq 0xf8869099 10: e9 4b ff ff ff jmpq 0xffffff60 15: e8 1f 90 86 f8 callq 0xf8869039 1a: e9 02 ff ff ff jmpq 0xffffff21 1f: e8 35 90 86 f8 callq 0xf8869059 24: e9 6c ff ff ff jmpq 0xffffff95 29: 55 push %rbp * 2a: 48 89 e5 mov %rsp,%rbp <-- trapping instruction 2d: 41 57 push %r15 2f: 48 8d 85 78 ff ff ff lea -0x88(%rbp),%rax 36: 41 56 push %r14 38: 48 c1 e8 03 shr $0x3,%rax 3c: 41 55 push %r13 3e: 41 54 push %r12