rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=88f/1/0x4000000000000002 softirq=16052/16053 fqs=303 (detected by 1, t=10505 jiffies, g=22733, q=868) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 6880 Comm: syz.3.936 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:kasan_check_range+0x1b7/0x290 mm/kasan/generic.c:189 Code: 49 8d 5f 07 4d 85 ff 49 0f 49 df 48 83 e3 f8 49 29 df 74 0e 41 80 3b 00 75 69 49 ff c3 49 ff cf 75 f2 5b 41 5c 41 5e 41 5f 5d 45 84 ff 0f 85 91 00 00 00 41 f7 c7 00 ff 00 00 0f 85 89 00 00 RSP: 0018:ffffc9000300e318 EFLAGS: 00000056 RAX: 0000000000000001 RBX: 0000000000000004 RCX: ffffffff815ce670 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901cb0c0 RBP: ffffc9000300e550 R08: ffffffff901cb0c7 R09: 1ffffffff2039618 R10: dffffc0000000000 R11: fffffbfff2039619 R12: ffff888019bae4f0 R13: 0000000000000002 R14: 0000000000000015 R15: ffff888019bae4f0 FS: 00007f052029b6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000107000 CR3: 000000007729e000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: instrument_atomic_read include/linux/instrumented.h:71 [inline] test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline] hlock_class kernel/locking/lockdep.c:197 [inline] check_wait_context kernel/locking/lockdep.c:4711 [inline] __lock_acquire+0x920/0x7b50 kernel/locking/lockdep.c:4962 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313 rcu_read_lock include/linux/rcupdate.h:740 [inline] __perf_output_begin kernel/events/ring_buffer.c:163 [inline] perf_output_begin_forward+0xa5/0xa30 kernel/events/ring_buffer.c:271 __perf_event_output kernel/events/core.c:7804 [inline] perf_event_output_forward+0x19b/0x2e0 kernel/events/core.c:7822 __perf_event_overflow+0x35f/0x550 kernel/events/core.c:9515 perf_tp_event+0x324/0xbe0 kernel/events/core.c:10047 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713 RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674 Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 c2 22 9d 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08 RSP: 0018:ffffc9000300ee20 EFLAGS: 00000206 RAX: 69a2b147732a2e00 RBX: 1ffff92000601dc8 RCX: 69a2b147732a2e00 RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a79c980 RBP: ffffc9000300ef00 R08: ffffffff901cb0c7 R09: 1ffffffff2039618 R10: dffffc0000000000 R11: fffffbfff2039619 R12: ffffffff8c323400 R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422 rcu_read_unlock include/linux/rcupdate.h:772 [inline] __mod_lruvec_page_state+0x1fe/0x330 mm/memcontrol.c:789 page_add_new_anon_rmap+0x571/0x890 mm/rmap.c:1203 wp_page_copy+0xe5d/0x2090 mm/memory.c:3116 handle_pte_fault mm/memory.c:4668 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x1fbd/0x4440 mm/memory.c:4883 do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355 handle_page_fault arch/x86/mm/fault.c:1443 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 RIP: 0010:copy_user_enhanced_fast_string+0xe/0x40 arch/x86/lib/copy_user_64.S:206 Code: 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 01 ca c3 90 90 90 90 90 90 90 0f 01 cb 83 fa 40 0f 82 70 ff ff ff 89 d1 a4 31 c0 0f 01 ca c3 90 90 90 90 90 90 90 90 90 90 89 d1 83 f8 RSP: 0018:ffffc9000300f4b8 EFLAGS: 00050206 RAX: ffffffff83e09101 RBX: 0000000000008000 RCX: 0000000000006040 RDX: 0000000000008000 RSI: ffff88807eeb1fc0 RDI: 0000200000107000 RBP: ffffc9000300f608 R08: ffff88807eeb7fff R09: 1ffff1100fdd6fff R10: dffffc0000000000 R11: ffffed100fdd7000 R12: ffff88807eeb0000 R13: 00000000000080ff R14: 0000200000105040 R15: 0000000000103a80 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline] raw_copy_to_user arch/x86/include/asm/uaccess_64.h:58 [inline] copyout lib/iov_iter.c:157 [inline] _copy_to_iter+0x322/0x1170 lib/iov_iter.c:670 __skb_datagram_iter+0x2e1/0x740 net/core/datagram.c:455 skb_copy_datagram_iter+0xad/0x1f0 net/core/datagram.c:541 skb_copy_datagram_msg include/linux/skbuff.h:3773 [inline] unix_stream_read_actor+0x68/0xa0 net/unix/af_unix.c:2829 unix_stream_read_generic+0xd1c/0x2180 net/unix/af_unix.c:2748 unix_stream_recvmsg+0x16f/0x1d0 net/unix/af_unix.c:2867 ____sys_recvmsg+0x2ca/0x5b0 net/socket.c:-1 ___sys_recvmsg+0x213/0x5c0 net/socket.c:2707 __sys_recvmsg net/socket.c:2737 [inline] __do_sys_recvmsg net/socket.c:2747 [inline] __se_sys_recvmsg net/socket.c:2744 [inline] __x64_sys_recvmsg+0x201/0x2d0 net/socket.c:2744 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f0522041e59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f052029b028 EFLAGS: 00000246 ORIG_RAX: 000000000000002f RAX: ffffffffffffffda RBX: 00007f05222bafa0 RCX: 00007f0522041e59 RDX: 0000000040000100 RSI: 0000200000001140 RDI: 0000000000000006 RBP: 00007f05220d7e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f05222bb038 R14: 00007f05222bafa0 R15: 00007ffee8162638 rcu: rcu_preempt kthread starved for 8990 jiffies! g22733 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:27920 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11c3/0x4350 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117 rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145 kthread+0x42e/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 1 CPU: 1 PID: 6883 Comm: syz.3.936 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline] rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487 print_other_cpu_stall+0x1110/0x1270 kernel/rcu/tree_stall.h:592 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline] rcu_pending kernel/rcu/tree.c:3936 [inline] rcu_sched_clock_irq+0x845/0x1120 kernel/rcu/tree.c:2619 update_process_times+0x193/0x200 kernel/time/timer.c:2021 tick_sched_handle kernel/time/tick-sched.c:254 [inline] tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x4b0/0xb60 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline] __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline] RIP: 0010:arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline] RIP: 0010:kvm_wait+0x159/0x1b0 arch/x86/kernel/kvm.c:918 Code: 89 df 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 75 4b 0f b6 1f e8 97 80 4a 00 44 38 e3 75 10 66 90 0f 00 2d c9 e9 f3 08 fb f4 16 ff ff ff fb e9 10 ff ff ff e8 67 3c 85 08 89 f9 80 e1 07 38 RSP: 0018:ffffc90002f8f220 EFLAGS: 00000246 RAX: 1f8cf7c494c25800 RBX: 0000000000000003 RCX: 1f8cf7c494c25800 RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a79c980 RBP: ffffc90002f8f2d0 R08: ffffffff901cb0c7 R09: 1ffffffff2039618 R10: dffffc0000000000 R11: fffffbfff2039619 R12: 0000000000000003 R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff920005f1e44 pv_wait arch/x86/include/asm/paravirt.h:597 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x605/0x9b0 kernel/locking/qspinlock.c:508 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:585 [inline] queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51 queued_spin_lock include/asm-generic/qspinlock.h:85 [inline] do_raw_spin_lock+0x265/0x2f0 kernel/locking/spinlock_debug.c:115 spin_lock include/linux/spinlock.h:364 [inline] do_anonymous_page mm/memory.c:3818 [inline] handle_pte_fault mm/memory.c:4648 [inline] __handle_mm_fault mm/memory.c:4785 [inline] handle_mm_fault+0x2f41/0x4440 mm/memory.c:4883 do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355 handle_page_fault arch/x86/mm/fault.c:1443 [inline] exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 RIP: 0010:copy_user_enhanced_fast_string+0xe/0x40 arch/x86/lib/copy_user_64.S:206 Code: 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 01 ca c3 90 90 90 90 90 90 90 0f 01 cb 83 fa 40 0f 82 70 ff ff ff 89 d1 a4 31 c0 0f 01 ca c3 90 90 90 90 90 90 90 90 90 90 89 d1 83 f8 RSP: 0018:ffffc90002f8f818 EFLAGS: 00050202 RAX: ffffffff83e0c601 RBX: 0000000000000ec0 RCX: 0000000000000dc0 RDX: 0000000000000ec0 RSI: 0000200000115000 RDI: ffff88807b75e100 RBP: ffffc90002f8f968 R08: ffff88807b75eebf R09: 1ffff1100f6ebdd7 R10: dffffc0000000000 R11: ffffed100f6ebdd8 R12: ffff88807b75e000 R13: 0000000000000eff R14: 0000200000114f00 R15: 0000000000114940 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline] raw_copy_from_user arch/x86/include/asm/uaccess_64.h:52 [inline] copyin lib/iov_iter.c:168 [inline] _copy_from_iter+0x322/0x1160 lib/iov_iter.c:777 copy_from_iter include/linux/uio.h:167 [inline] skb_copy_datagram_from_iter+0xf1/0x6c0 net/core/datagram.c:567 unix_stream_sendmsg+0x678/0xc90 net/unix/af_unix.c:2094 sock_sendmsg_nosec net/socket.c:706 [inline] __sock_sendmsg net/socket.c:718 [inline] sock_write_iter+0x2a6/0x3a0 net/socket.c:1090 call_write_iter include/linux/fs.h:2173 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x748/0xd70 fs/read_write.c:594 ksys_write+0x153/0x260 fs/read_write.c:647 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f0522041e59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f052027a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f05222bb090 RCX: 00007f0522041e59 RDX: 00000000fffffeff RSI: 00002000000005c0 RDI: 0000000000000005 RBP: 00007f05220d7e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f05222bb128 R14: 00007f05222bb090 R15: 00007ffee8162638