rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P3562/1:b..l (detected by 1, t=10502 jiffies, g=6161, q=77) task:udevd state:R running task stack:25056 pid: 3562 ppid: 1 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11bb/0x4390 kernel/sched/core.c:6395 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6571 preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6596 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] _raw_spin_unlock_irqrestore+0xf6/0x100 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:419 [inline] __wake_up_common_lock kernel/sched/wait.c:140 [inline] __wake_up_sync_key+0x11b/0x180 kernel/sched/wait.c:205 sock_def_readable+0x136/0x250 net/core/sock.c:3098 __netlink_sendskb net/netlink/af_netlink.c:1264 [inline] netlink_sendskb+0x97/0x130 net/netlink/af_netlink.c:1270 netlink_sendmsg+0x8ab/0xbc0 net/netlink/af_netlink.c:1918 sock_sendmsg_nosec net/socket.c:706 [inline] __sock_sendmsg net/socket.c:718 [inline] ____sys_sendmsg+0x5a2/0x8c0 net/socket.c:2446 ___sys_sendmsg+0x1f0/0x260 net/socket.c:2500 __sys_sendmsg net/socket.c:2529 [inline] __do_sys_sendmsg net/socket.c:2538 [inline] __se_sys_sendmsg+0x190/0x250 net/socket.c:2536 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: 0033:0x7f1628ad8407 RSP: 002b:00007fff050ccf20 EFLAGS: 00000202 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f16289ea880 RCX: 00007f1628ad8407 RDX: 0000000000000000 RSI: 00007fff050ccf80 RDI: 0000000000000004 RBP: 0000558926609ae0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00000000000000b9 R13: 00005589265f69e0 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread starved for 10521 jiffies! g6161 f0x0 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:27880 pid: 15 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5049 [inline] __schedule+0x11bb/0x4390 kernel/sched/core.c:6395 schedule+0x11b/0x1e0 kernel/sched/core.c:6478 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972 rcu_gp_kthread+0x98/0x350 kernel/rcu/tree.c:2145 kthread+0x436/0x520 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: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 4455 Comm: syz.1.41 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:preempt_count_add+0x4/0x190 kernel/sched/core.c:5499 Code: 80 c1 03 38 c1 7c 97 48 8b 3c 24 e8 96 c3 6a 00 eb 8c e9 f5 fe ff ff 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 41 57 41 56 <53> 49 bf 00 00 00 00 00 fc ff df 48 c7 c0 80 4f 0c 96 48 c1 e8 03 RSP: 0018:ffffc90000007c68 EFLAGS: 00000046 RAX: 0000000000000806 RBX: ffff8880b902a240 RCX: ffff88802812bb80 RDX: 0000000000010000 RSI: ffffffff8a59e560 RDI: 0000000000000001 RBP: ffffc90000007d10 R08: dffffc0000000000 R09: fffffbfff1ad33a6 R10: fffffbfff1ad33a6 R11: 1ffffffff1ad33a5 R12: ffff8880b902a350 R13: 1ffff1101720546a R14: 1ffff92000000f90 R15: dffffc0000000000 FS: 00007f254cac66c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000058 CR3: 000000005a09b000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock_irq include/linux/spinlock_api_smp.h:127 [inline] _raw_spin_lock_irq+0x84/0xe0 kernel/locking/spinlock.c:170 __run_hrtimer kernel/time/hrtimer.c:1689 [inline] __hrtimer_run_queues+0x5ff/0xc40 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x3bb/0x8d0 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:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202 Code: f6 ff 0f 1f 00 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 de 9e a9 f7 48 89 df e8 a6 73 aa f7 e8 41 0d cb f7 fb bf 01 00 00 00 76 95 9e f7 65 8b 05 07 93 4f 76 85 c0 74 02 5b c3 e8 b4 9d 4d RSP: 0018:ffffc900031dfbc0 EFLAGS: 00000282 RAX: a81d9f3c93449c00 RBX: ffff88807b5c9280 RCX: a81d9f3c93449c00 RDX: dffffc0000000000 RSI: ffffffff8a0b1c60 RDI: 0000000000000001 RBP: 0000000000000000 R08: dffffc0000000000 R09: ffffed100f6b9251 R10: ffffed100f6b9251 R11: 1ffff1100f6b9250 R12: ffff88807b5c9280 R13: 0000000000000021 R14: dffffc0000000000 R15: 000000001c000004 spin_unlock_irq include/linux/spinlock.h:414 [inline] get_signal+0x11d6/0x12c0 kernel/signal.c:2903 arch_do_signal_or_restart+0xc1/0x1300 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f254e85f6c7 Code: ff ff 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 RSP: 002b:00007f254cac6038 EFLAGS: 00000246 RAX: 0000000000000049 RBX: 00007f254eab5fa0 RCX: 00007f254e85f6c9 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000004 RBP: 00007f254e8e1f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f254eab6038 R14: 00007f254eab5fa0 R15: 00007ffc7727c6f8