rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=12141, q=53) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294978926-4294968424), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g12141 f0x2 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:28952 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 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 6984 Comm: syz-executor388 Not tainted 5.15.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:lock_acquire kernel/locking/lockdep.c:5628 [inline] RIP: 0010:lock_acquire+0x1d3/0x510 kernel/locking/lockdep.c:5590 Code: ff ff 48 c7 c7 20 e9 8b 89 48 83 c4 20 e8 85 0e db 07 b8 ff ff ff ff 65 0f c1 05 48 96 a6 7e 83 f8 01 0f 85 b4 02 00 00 9c 58 c4 02 0f 85 9f 02 00 00 48 83 7c 24 08 00 74 01 fb 48 b8 00 00 RSP: 0018:ffffc90000007c20 EFLAGS: 00000046 RAX: 0000000000000046 RBX: 1ffff92000000f86 RCX: ffffffff815b111f RDX: 1ffff1100e69759b RSI: 0000000000010002 RDI: 0000000000000000 RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8fd059e7 R10: fffffbfff1fa0b3c R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff904c3b88 R15: 0000000000000000 FS: 00007f94b8679700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fffa1e15c48 CR3: 0000000023e50000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 debug_object_activate+0x12e/0x3e0 lib/debugobjects.c:661 debug_hrtimer_activate kernel/time/hrtimer.c:420 [inline] debug_activate kernel/time/hrtimer.c:475 [inline] enqueue_hrtimer+0x27/0x3e0 kernel/time/hrtimer.c:1084 __run_hrtimer kernel/time/hrtimer.c:1702 [inline] __hrtimer_run_queues+0xb02/0xe50 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:get_tty_driver drivers/tty/tty_io.c:321 [inline] RIP: 0010:tty_lookup_driver+0xa7/0x550 drivers/tty/tty_io.c:1961 Code: 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 81 04 00 00 49 8d 7c 24 30 41 8b 6c 24 2c 48 89 f8 48 c1 e8 03 42 0f b6 04 30 e5 14 84 c0 74 08 3c 03 0f 8e 52 04 00 00 41 0b 6c 24 30 89 df RSP: 0018:ffffc90003697888 EFLAGS: 00000a06 RAX: 0000000000000000 RBX: 0000000000400043 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff842f184b RDI: ffff88801e667d30 RBP: 00000000000001fd R08: 0000000000400043 R09: ffffffff842f1805 R10: ffffffff842f18a4 R11: 0000000000400043 R12: ffff88801e667d00 R13: ffffc90003697928 R14: dffffc0000000000 R15: ffff88801bb34d00 tty_open_by_driver drivers/tty/tty_io.c:2063 [inline] tty_open+0x56d/0x1000 drivers/tty/tty_io.c:2146 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: 0033:0x7f94b86c7af9 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:00007f94b8679318 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f94b874f3e8 RCX: 00007f94b86c7af9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f94b874f3e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 7974742f7665642f R13: 00007fffa1e15bef R14: 00007f94b8679400 R15: 0000000000022000 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 2.049 msecs ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 48 c7 c7 20 e9 8b 89 mov $0xffffffff898be920,%rdi 7: 48 83 c4 20 add $0x20,%rsp b: e8 85 0e db 07 callq 0x7db0e95 10: b8 ff ff ff ff mov $0xffffffff,%eax 15: 65 0f c1 05 48 96 a6 xadd %eax,%gs:0x7ea69648(%rip) # 0x7ea69665 1c: 7e 1d: 83 f8 01 cmp $0x1,%eax 20: 0f 85 b4 02 00 00 jne 0x2da 26: 9c pushfq 27: 58 pop %rax * 28: f6 c4 02 test $0x2,%ah <-- trapping instruction 2b: 0f 85 9f 02 00 00 jne 0x2d0 31: 48 83 7c 24 08 00 cmpq $0x0,0x8(%rsp) 37: 74 01 je 0x3a 39: fb sti 3a: 48 rex.W 3b: b8 .byte 0xb8