rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=28317, q=66) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294966768-4294956266), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g28317 f0x2 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:28952 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0x940/0x26f0 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: 10780 Comm: syz-executor.0 Not tainted 5.15.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:check_preemption_disabled+0x35/0x170 lib/smp_processor_id.c:55 Code: 89 fd 53 0f 1f 44 00 00 65 44 8b 25 fd 37 cc 76 65 8b 1d 8e 92 cc 76 81 e3 ff ff ff 7f 31 ff 89 de 0f 1f 44 00 00 85 db 74 11 <0f> 1f 44 00 00 44 89 e0 5b 5d 41 5c 41 5d 41 5e c3 0f 1f 44 00 00 RSP: 0018:ffffc90000fd89b8 EFLAGS: 00000002 RAX: 0000000000000000 RBX: 0000000000010001 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000010001 RDI: 0000000000000000 RBP: ffffffff89e3a260 R08: 0000000000000000 R09: ffff8880b9d32a8b R10: ffffed10173a6551 R11: 0000000000000000 R12: 0000000000000001 R13: ffffffff898be600 R14: 00000000ffffffff R15: ffffc90000fd8b20 FS: 00007fb28b4aa700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe486ddc4c CR3: 0000000042b9b000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lockdep_recursion_inc kernel/locking/lockdep.c:433 [inline] lock_is_held_type+0x63/0x140 kernel/locking/lockdep.c:5667 lock_is_held include/linux/lockdep.h:283 [inline] rcu_read_lock_sched_held+0x3a/0x70 kernel/rcu/update.c:125 trace_lock_release include/trace/events/lock.h:58 [inline] lock_release+0x522/0x720 kernel/locking/lockdep.c:5636 rcu_lock_release include/linux/rcupdate.h:272 [inline] rcu_read_unlock include/linux/rcupdate.h:720 [inline] __perf_event_output kernel/events/core.c:7498 [inline] perf_event_output_forward+0x161/0x280 kernel/events/core.c:7507 __perf_event_overflow+0x13c/0x3d0 kernel/events/core.c:9177 perf_swevent_hrtimer+0x37c/0x3f0 kernel/events/core.c:10567 __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:tty_open_by_driver drivers/tty/tty_io.c:2059 [inline] RIP: 0010:tty_open+0x543/0x1000 drivers/tty/tty_io.c:2146 Code: 80 3c 30 00 0f 85 64 09 00 00 49 81 7f 28 e0 86 f2 89 0f 85 de fb ff ff e8 5a ba 46 fd 49 c7 47 28 20 89 f2 89 e9 cc fb ff ff 48 ba 46 fd 31 f6 48 c7 c7 00 6b 38 8c c7 44 24 68 ff ff ff ff RSP: 0018:ffffc90005a4f8c0 EFLAGS: 00000283 RAX: 0000000000000000 RBX: 0000000000400043 RCX: 0000000000400043 RDX: 0000000000000000 RSI: ffff88807daa0040 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000500000 R09: ffff8880b9d32a8b R10: ffffffff842e76f1 R11: 0000000000086089 R12: 00000000fffffff5 R13: ffff8880212ff4f0 R14: dffffc0000000000 R15: ffff8880212ff340 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: 0033:0x7fb28df338d9 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:00007fb28b4aa188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fb28e037f60 RCX: 00007fb28df338d9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007fb28df8dcb4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc7006df9f R14: 00007fb28b4aa300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: 89 fd mov %edi,%ebp 2: 53 push %rbx 3: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 8: 65 44 8b 25 fd 37 cc mov %gs:0x76cc37fd(%rip),%r12d # 0x76cc380d f: 76 10: 65 8b 1d 8e 92 cc 76 mov %gs:0x76cc928e(%rip),%ebx # 0x76cc92a5 17: 81 e3 ff ff ff 7f and $0x7fffffff,%ebx 1d: 31 ff xor %edi,%edi 1f: 89 de mov %ebx,%esi 21: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 26: 85 db test %ebx,%ebx 28: 74 11 je 0x3b * 2a: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) <-- trapping instruction 2f: 44 89 e0 mov %r12d,%eax 32: 5b pop %rbx 33: 5d pop %rbp 34: 41 5c pop %r12 36: 41 5d pop %r13 38: 41 5e pop %r14 3a: c3 retq 3b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)