rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (10 ticks this GP) idle=9cd4/1/0x4000000000000000 softirq=10535/10536 fqs=12 rcu: (detected by 0, t=10502 jiffies, g=8237, q=43 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 5910 Comm: syz.1.12 Not tainted 6.6.102-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:hlock_class kernel/locking/lockdep.c:223 [inline] RIP: 0010:mark_lock+0x5d/0x320 kernel/locking/lockdep.c:4656 Code: c0 0f 85 74 02 00 00 41 0f b6 47 02 24 03 3c 01 bd 09 00 00 00 83 dd 00 41 bc 01 00 00 00 89 e9 41 d3 e4 4d 8d 7e 20 4c 89 f8 <48> c1 e8 03 42 0f b6 04 28 84 c0 0f 85 22 02 00 00 41 8b 07 41 89 RSP: 0018:ffffc900001efcc0 EFLAGS: 00000006 RAX: ffff888023ffc7c8 RBX: ffff888023ffbc00 RCX: 0000000000000009 RDX: 0000000000000008 RSI: ffff888023ffc7a8 RDI: ffff888023ffbc00 RBP: 0000000000000009 R08: dffffc0000000000 R09: 1ffffffff21b46a0 R10: dffffc0000000000 R11: fffffbfff21b46a1 R12: 0000000000000200 R13: dffffc0000000000 R14: ffff888023ffc7a8 R15: ffff888023ffc7c8 FS: 00007fa574c1d6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000033000 CR3: 0000000021065000 CR4: 00000000003506e0 Call Trace: mark_usage kernel/locking/lockdep.c:4599 [inline] __lock_acquire+0xd49/0x7c80 kernel/locking/lockdep.c:5091 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754 rcu_lock_acquire include/linux/rcupdate.h:334 [inline] rcu_read_lock include/linux/rcupdate.h:786 [inline] __perf_event_output kernel/events/core.c:7969 [inline] perf_event_output_forward+0xb5/0x3a0 kernel/events/core.c:7992 __perf_event_overflow+0x447/0x630 kernel/events/core.c:9717 perf_swevent_overflow kernel/events/core.c:9793 [inline] perf_swevent_event+0x2f5/0x5c0 kernel/events/core.c:-1 perf_tp_event+0x4f9/0x13a0 kernel/events/core.c:10343 perf_trace_run_bpf_submit+0xf4/0x1c0 kernel/events/core.c:10267 perf_trace_preemptirq_template+0x281/0x340 include/trace/events/preemptirq.h:14 trace_irq_enable+0xbf/0xe0 include/trace/events/preemptirq.h:40 trace_hardirqs_on+0x18/0x40 kernel/trace/trace_preemptirq.c:56 asm_sysvec_irq_work+0x1a/0x20 arch/x86/include/asm/idtentry.h:723 RIP: 0010:rcu_read_unlock_special+0x88/0x4c0 kernel/rcu/tree_plugin.h:682 Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 39 58 93 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b RSP: 0018:ffffc900001f0780 EFLAGS: 00000206 RAX: 57bb0f3337ae4600 RBX: 1ffff9200003e0f8 RCX: 57bb0f3337ae4600 RDX: dffffc0000000000 RSI: ffffffff8aaab9c0 RDI: ffffffff8afc66c0 RBP: ffffc900001f0878 R08: ffffffff90da35c7 R09: 1ffffffff21b46b8 R10: dffffc0000000000 R11: fffffbfff21b46b9 R12: ffffffff8cd35400 R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000002 __rcu_read_unlock+0x7c/0xd0 kernel/rcu/tree_plugin.h:426 rcu_read_unlock include/linux/rcupdate.h:818 [inline] __ip_queue_xmit+0x112b/0x1a10 net/ipv4/ip_output.c:536 __tcp_transmit_skb+0x1c97/0x32a0 net/ipv4/tcp_output.c:1422 tcp_delack_timer_handler+0x2ad/0x440 net/ipv4/tcp_timer.c:330 tcp_delack_timer+0x18c/0x2e0 net/ipv4/tcp_timer.c:353 call_timer_fn+0x16e/0x530 kernel/time/timer.c:1700 expire_timers kernel/time/timer.c:1751 [inline] __run_timers+0x52d/0x7d0 kernel/time/timer.c:2022 run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2035 handle_softirqs+0x280/0x820 kernel/softirq.c:578 __do_softirq kernel/softirq.c:612 [inline] invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline] sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:preempt_schedule_irq+0xb0/0x140 kernel/sched/core.c:7009 Code: 44 24 20 f6 44 24 21 02 74 0b 0f 0b 48 f7 03 08 00 00 00 74 63 bf 01 00 00 00 e8 4b da e5 f6 e8 46 5f 16 f7 fb bf 01 00 00 00 db b5 ff ff 48 c7 44 24 40 00 00 00 00 9c 8f 44 24 40 8b 44 24 RSP: 0018:ffffc90004c1ea60 EFLAGS: 00000286 RAX: 57bb0f3337ae4600 RBX: 0000000000000000 RCX: 57bb0f3337ae4600 RDX: dffffc0000000000 RSI: ffffffff8aaab9c0 RDI: 0000000000000001 RBP: ffffc90004c1eb10 R08: ffffffff90da3537 R09: 1ffffffff21b46a6 R10: dffffc0000000000 R11: fffffbfff21b46a7 R12: 0000000000000000 R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff92000983d4c irqentry_exit+0x67/0x70 kernel/entry/common.c:438 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687 RIP: 0010:stack_trace_consume_entry+0x97/0x270 kernel/stacktrace.c:93 Code: 00 44 8b 23 45 85 e4 74 21 41 ff cc 41 0f b6 04 17 84 c0 0f 85 73 01 00 00 44 89 23 b0 01 e9 99 00 00 00 31 c0 e9 92 00 00 00 <48> 89 f8 48 c1 e8 03 80 3c 10 00 74 29 49 89 ff 48 89 74 24 08 49 RSP: 0018:ffffc90004c1ebd8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffc90004c1ecec RCX: ffff888023ffbc00 RDX: dffffc0000000000 RSI: ffffffff8a801256 RDI: ffffc90004c1ece0 RBP: 1ffff92000983d9e R08: ffffc90004c1ecf0 R09: 0000000000000009 R10: 0000000000000004 R11: 0000000000000002 R12: 0000000000000000 R13: 1ffff92000983d9d R14: ffffc90004c1ece8 R15: 1ffff92000983d9d arch_stack_walk+0x138/0x190 arch/x86/kernel/stacktrace.c:27 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 save_stack+0xf7/0x1f0 mm/page_owner.c:128 __set_page_owner+0x1d/0x60 mm/page_owner.c:192 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554 prep_new_page mm/page_alloc.c:1561 [inline] get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457 __folio_alloc+0x10/0x20 mm/page_alloc.c:4489 vma_alloc_folio+0x47a/0x8f0 mm/mempolicy.c:2242 wp_page_copy mm/memory.c:3089 [inline] do_wp_page+0x128e/0x3630 mm/memory.c:3468 handle_pte_fault mm/memory.c:5041 [inline] __handle_mm_fault mm/memory.c:5166 [inline] handle_mm_fault+0x12d4/0x4920 mm/memory.c:5331 do_user_addr_fault+0x738/0x12e0 arch/x86/mm/fault.c:1373 handle_page_fault arch/x86/mm/fault.c:1465 [inline] exc_page_fault+0x67/0x110 arch/x86/mm/fault.c:1521 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608 RIP: 0010:rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:71 Code: 75 f1 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 df 83 f9 08 73 e8 eb c9 a4 c3 48 8b 06 48 89 07 48 8d 47 08 48 83 e0 f8 48 29 f8 48 01 RSP: 0018:ffffc90004c1f718 EFLAGS: 00050206 RAX: ffffffff841bfa01 RBX: 1ffff92000983fc7 RCX: 000000000000db40 RDX: 0000000000000000 RSI: ffff88805cc82778 RDI: 0000200000033000 RBP: ffffc90004c1f878 R08: ffff88805cc902b7 R09: 1ffff1100b992056 R10: dffffc0000000000 R11: ffffed100b992057 R12: ffff88805cc800e8 R13: 00000000000101d0 R14: 00000000000101d0 R15: ffffc90004c1fe48 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline] raw_copy_to_user arch/x86/include/asm/uaccess_64.h:133 [inline] copyout lib/iov_iter.c:168 [inline] _copy_to_iter+0x249/0x10d0 lib/iov_iter.c:316 __skb_datagram_iter+0xdb/0x780 net/core/datagram.c:419 skb_copy_datagram_iter+0xb1/0x200 net/core/datagram.c:535 skb_copy_datagram_msg include/linux/skbuff.h:4014 [inline] tipc_recvstream+0x72b/0xe70 net/tipc/socket.c:2072 sock_recvmsg_nosec net/socket.c:1046 [inline] sock_recvmsg net/socket.c:1068 [inline] ____sys_recvmsg+0x29e/0x5b0 net/socket.c:2814 ___sys_recvmsg+0x1b6/0x510 net/socket.c:2856 __sys_recvmsg net/socket.c:2886 [inline] __do_sys_recvmsg net/socket.c:2896 [inline] __se_sys_recvmsg net/socket.c:2893 [inline] __x64_sys_recvmsg+0x1f2/0x2c0 net/socket.c:2893 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fa573d8ebe9 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fa574c1d038 EFLAGS: 00000246 ORIG_RAX: 000000000000002f RAX: ffffffffffffffda RBX: 00007fa573fb5fa0 RCX: 00007fa573d8ebe9 RDX: 0000000000001f00 RSI: 0000200000000500 RDI: 000000000000000c RBP: 00007fa573e11e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fa573fb6038 R14: 00007fa573fb5fa0 R15: 00007ffefa30d358 rcu: rcu_preempt kthread timer wakeup didn't happen for 10476 jiffies! g8237 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=4545 rcu: rcu_preempt kthread starved for 10477 jiffies! g8237 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:26920 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5380 [inline] __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699 schedule+0xbd/0x170 kernel/sched/core.c:6773 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 PID: 5908 Comm: syz.1.12 Not tainted 6.6.102-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:148 Code: cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d e3 e6 3a 00 f3 0f 1e fa fb f4 cc cc cc cc cc cc cc cc cc cc cc cc 66 0f 1f 00 55 41 57 41 56 RSP: 0018:ffffc90004bcf9d8 EFLAGS: 000002d3 RAX: ffffffff813a13aa RBX: 0000000000000003 RCX: ffff88802d9fda00 RDX: 0000000000000000 RSI: ffffffff8aaab9c0 RDI: ffffffff8afc66c0 RBP: ffffc90004bcfab0 R08: ffffffff90da35c7 R09: 1ffffffff21b46b8 R10: dffffc0000000000 R11: fffffbfff21b46b9 R12: dffffc0000000000 R13: 0000000000000200 R14: 0000000000000003 R15: 1ffff92000979f40 FS: 000055557e05d500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2e10dff8 CR3: 0000000021065000 CR4: 00000000003506f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] kvm_wait+0x22f/0x290 arch/x86/kernel/kvm.c:1058 pv_wait arch/x86/include/asm/paravirt.h:598 [inline] pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline] __pv_queued_spin_lock_slowpath+0x61a/0x9d0 kernel/locking/qspinlock.c:511 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline] queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline] queued_spin_lock include/asm-generic/qspinlock.h:114 [inline] do_raw_spin_lock+0x24e/0x2c0 kernel/locking/spinlock_debug.c:115 spin_lock_bh include/linux/spinlock.h:356 [inline] lock_sock_nested+0x6a/0x100 net/core/sock.c:3513 lock_sock include/net/sock.h:1731 [inline] tcp_close+0x1d/0x110 net/ipv4/tcp.c:2957 inet_release+0x13d/0x180 net/ipv4/af_inet.c:434 __sock_release net/socket.c:659 [inline] sock_close+0xbd/0x230 net/socket.c:1421 __fput+0x234/0x970 fs/file_table.c:384 task_work_run+0x1ce/0x250 kernel/task_work.c:239 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fa573d8ebe9 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffefa30d4b8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007fa573fb7da0 RCX: 00007fa573d8ebe9 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007fa573fb7da0 R08: 0000000000015c9c R09: 00000017fa30d7af R10: 00007fa573fb7cb0 R11: 0000000000000246 R12: 0000000000012af7 R13: 00007fa573fb6180 R14: ffffffffffffffff R15: 00007ffefa30d5d0