rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P8348/1:b..l P12595/1:b..l P5269/1:b..l rcu: (detected by 0, t=10502 jiffies, g=122557, q=1551 ncpus=1) task:dhcpcd state:R running task stack:22616 pid:5269 tgid:5269 ppid:5268 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7277 preempt_schedule_common+0x3c/0xb0 kernel/sched/core.c:7456 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:211 [inline] _raw_spin_unlock_irqrestore+0x61/0x80 kernel/locking/spinlock.c:221 sock_def_readable+0x154/0x600 net/core/sock.c:3668 unix_dgram_sendmsg+0xc8f/0x1810 net/unix/af_unix.c:2300 unix_seqpacket_sendmsg+0x12a/0x1d0 net/unix/af_unix.c:2545 sock_sendmsg_nosec net/socket.c:800 [inline] __sock_sendmsg net/socket.c:815 [inline] sock_write_iter+0x53a/0x5b0 net/socket.c:1266 do_iter_readv_writev+0x6f7/0x930 fs/read_write.c:828 vfs_writev+0x360/0xdd0 fs/read_write.c:1058 do_writev+0x28a/0x340 fs/read_write.c:1104 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3752af3407 RSP: 002b:00007ffcbae61e00 EFLAGS: 00000202 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f3752a69780 RCX: 00007f3752af3407 RDX: 0000000000000002 RSI: 00007ffcbae61ea0 RDI: 000000000000000b RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000b R13: 00007f3752a69708 R14: 0000000000000000 R15: 00007ffcbae71fb0 task:syz.6.1614 state:R running task stack:27160 pid:12595 tgid:12595 ppid:7448 task_flags:0x40044c flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7277 preempt_schedule_common+0x3c/0xb0 kernel/sched/core.c:7456 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:201 [inline] _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:213 spin_unlock include/linux/spinlock.h:401 [inline] zap_pte_range mm/memory.c:2095 [inline] zap_pmd_range mm/memory.c:2151 [inline] zap_pud_range mm/memory.c:2179 [inline] zap_p4d_range mm/memory.c:2200 [inline] __zap_vma_range+0x16b0/0x48e0 mm/memory.c:2240 unmap_vmas+0x299/0x5f0 mm/memory.c:2309 exit_mmap+0x1ef/0xa00 mm/mmap.c:1315 __mmput+0x12a/0x410 kernel/fork.c:1193 mmput+0x67/0x80 kernel/fork.c:1216 exit_mm kernel/exit.c:617 [inline] do_exit+0x8b1/0x2ae0 kernel/exit.c:999 do_group_exit+0xd5/0x2a0 kernel/exit.c:1154 get_signal+0x1ec7/0x21e0 kernel/signal.c:3051 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x139/0x700 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline] do_syscall_64+0x661/0x790 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1b3975e98e RSP: 002b:00007f1b3a595f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6 RAX: fffffffffffffdfc RBX: 00007f1b3a5966c0 RCX: 00007f1b3975e98e RDX: 00007f1b3a595fb0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f1b3983506b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1b39a26038 R14: 00007f1b39a25fa0 R15: 00007ffe990e6ef8 task:syz.6.585 state:R running task stack:27160 pid:8348 tgid:8348 ppid:7448 task_flags:0x40044c flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7277 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:7599 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x205/0xa10 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:deref_stack_reg arch/x86/kernel/unwind_orc.c:422 [inline] RIP: 0010:unwind_next_frame+0x157d/0x2090 arch/x86/kernel/unwind_orc.c:677 Code: 0f 84 f3 ed ff ff 48 89 ef e8 9f e2 ff ff 49 8d 7d 40 48 89 fa 48 89 c5 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 <0f> 84 17 fa ff ff e8 f8 ac c5 00 e9 0d fa ff ff 48 b8 00 00 00 00 RSP: 0018:ffffc900040b7500 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: 0000000000000001 RCX: ffffffff91e6d836 RDX: 1ffff92000816ec0 RSI: ffffc900040b7650 RDI: ffffc900040b7600 RBP: ffff88802ae0a580 R08: 0000000000000001 R09: 0000000000000007 R10: 0000000000000200 R11: 000000000000b0a9 R12: ffffc900040b7610 R13: ffffc900040b75c0 R14: ffffc900040b7660 R15: ffffc900040b75f4 __unwind_start+0x3cd/0x7e0 arch/x86/kernel/unwind_orc.c:787 unwind_start arch/x86/include/asm/unwind.h:64 [inline] arch_stack_walk+0x73/0xf0 arch/x86/kernel/stacktrace.c:24 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 save_stack+0x162/0x1e0 mm/page_owner.c:183 __reset_page_owner+0x84/0x190 mm/page_owner.c:338 reset_page_owner include/linux/page_owner.h:26 [inline] __free_pages_prepare mm/page_alloc.c:1418 [inline] __free_frozen_pages+0x79f/0x10f0 mm/page_alloc.c:2962 tlb_batch_list_free mm/mmu_gather.c:161 [inline] tlb_finish_mmu+0x27d/0x810 mm/mmu_gather.c:552 exit_mmap+0x454/0xa00 mm/mmap.c:1328 __mmput+0x12a/0x410 kernel/fork.c:1193 mmput+0x67/0x80 kernel/fork.c:1216 exit_mm kernel/exit.c:617 [inline] do_exit+0x8b1/0x2ae0 kernel/exit.c:999 do_group_exit+0xd5/0x2a0 kernel/exit.c:1154 get_signal+0x1ec7/0x21e0 kernel/signal.c:3051 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x139/0x700 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline] do_syscall_64+0x661/0x790 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1b3975e98e RSP: 002b:00007f1b3a595f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6 RAX: fffffffffffffdfc RBX: 00007f1b3a5966c0 RCX: 00007f1b3975e98e RDX: 00007f1b3a595fb0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f1b3983506b R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1b39a26038 R14: 00007f1b39a25fa0 R15: 00007ffe990e6ef8 rcu: rcu_preempt kthread starved for 271 jiffies! g122557 f0x0 RCU_GP_WAIT_FQS(5) ->state=R ->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:28408 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5526 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7277 __schedule_loop kernel/sched/core.c:7354 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7369 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x8f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x17a/0x220 kernel/rcu/tree.c:2330 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 3229 Comm: kworker/R-bat_e Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2026 Workqueue: bat_events batadv_tt_purge RIP: 0010:rcu_is_watching+0x0/0xc0 kernel/rcu/tree.c:749 Code: 5b c3 cc cc cc cc 90 0f 0b 90 5b c3 cc cc cc cc e8 75 93 8f 00 eb cd 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 55 53 65 48 ff 05 8a d0 9c 12 e8 4d 9a e1 09 48 c7 c3 RSP: 0018:ffffc90000007978 EFLAGS: 00000202 RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000101 RDX: ffff888033dda580 RSI: ffffffff89a07b3d RDI: ffff888033dda580 RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000 R13: ffff8881c6a4e6c1 R14: ffff88806721d048 R15: ffff8881c6a4e640 FS: 0000000000000000(0000) GS:ffff888123b56000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007faa9b600218 CR3: 000000000eb96000 CR4: 00000000003526f0 Call Trace: rcu_read_lock_held_common kernel/rcu/update.c:109 [inline] rcu_read_lock_bh_held+0x22/0x60 kernel/rcu/update.c:374 sch_handle_ingress net/core/dev.c:4516 [inline] __netif_receive_skb_core.constprop.0+0x2392/0x3530 net/core/dev.c:6115 __netif_receive_skb_one_core+0xb0/0x1e0 net/core/dev.c:6262 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6377 process_backlog+0x487/0x1600 net/core/dev.c:6728 __napi_poll.constprop.0+0xaf/0x450 net/core/dev.c:7787 napi_poll net/core/dev.c:7850 [inline] net_rx_action+0xa40/0xf20 net/core/dev.c:8007 handle_softirqs+0x1e6/0x9d0 kernel/softirq.c:645 do_softirq kernel/softirq.c:546 [inline] do_softirq+0xaf/0xf0 kernel/softirq.c:533 __local_bh_enable_ip+0xff/0x120 kernel/softirq.c:473 spin_unlock_bh include/linux/spinlock.h:407 [inline] batadv_tt_global_purge net/batman-adv/translation-table.c:2390 [inline] batadv_tt_purge+0x25d/0xbd0 net/batman-adv/translation-table.c:3754 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 process_scheduled_works kernel/workqueue.c:3479 [inline] rescuer_thread+0x918/0x14e0 kernel/workqueue.c:3703 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245