rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4388/1:b..l P4282/1:b..l (detected by 1, t=10502 jiffies, g=19465, q=340 ncpus=2) task:udevd state:R running task stack:23904 pid:4282 ppid:3637 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561 preempt_schedule_notrace+0xca/0x110 kernel/sched/core.c:6823 preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35 rcu_is_watching+0x76/0xa0 kernel/rcu/tree.c:722 trace_lock_acquire include/trace/events/lock.h:24 [inline] lock_acquire+0xe8/0x490 kernel/locking/lockdep.c:5633 rcu_lock_acquire include/linux/rcupdate.h:350 [inline] rcu_read_lock include/linux/rcupdate.h:791 [inline] path_init+0x160/0x1200 fs/namei.c:2366 path_parentat fs/namei.c:2533 [inline] __filename_parentat+0x1f6/0x610 fs/namei.c:2558 filename_parentat fs/namei.c:2576 [inline] do_renameat2+0x1ef/0xc70 fs/namei.c:4946 __do_sys_rename fs/namei.c:5081 [inline] __se_sys_rename fs/namei.c:5079 [inline] __x64_sys_rename+0x82/0x90 fs/namei.c:5079 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fc4e4c7acc7 RSP: 002b:00007ffda0cf3078 EFLAGS: 00000206 ORIG_RAX: 0000000000000052 RAX: ffffffffffffffda RBX: 00005593808027a0 RCX: 00007fc4e4c7acc7 RDX: 00005593807e5010 RSI: 00007ffda0cf3090 RDI: 00007ffda0cf3490 RBP: 000055938080b820 R08: 00000000000001e0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 00007ffda0cf3090 R13: 00007ffda0cf3490 R14: 0000000000000000 R15: 000055935d07c9dd task:kworker/u4:7 state:R running task stack:24592 pid:4388 ppid:2 flags:0x00004000 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873 irqentry_exit+0x63/0x70 kernel/entry/common.c:439 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691 RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:122 [inline] RIP: 0010:lock_acquire+0x13f/0x490 kernel/locking/lockdep.c:5638 Code: 65 8b 05 c4 80 9f 7e 85 c0 0f 85 2f 01 00 00 65 4c 8b 35 74 76 9f 7e 49 81 c6 dc 0a 00 00 4c 89 f0 48 c1 e8 03 42 0f b6 04 38 <84> c0 0f 85 19 02 00 00 41 83 3e 00 0f 85 02 01 00 00 48 c7 84 24 RSP: 0018:ffffc900041a7920 EFLAGS: 00000a03 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 6f5e50dc457d9400 RDX: 0000000000000000 RSI: ffffffff8adef740 RDI: ffffffff8adef700 RBP: ffffc900041a7a28 R08: dffffc0000000000 R09: fffffbfff1c3ed56 R10: fffffbfff1c3ed56 R11: 1ffffffff1c3ed55 R12: 0000000000000001 R13: 1ffff92000834f30 R14: ffff88802968a89c R15: dffffc0000000000 rcu_lock_acquire include/linux/rcupdate.h:350 [inline] rcu_read_lock include/linux/rcupdate.h:791 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:754 [inline] batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:825 [inline] batadv_iv_ogm_schedule+0x413/0xe90 net/batman-adv/bat_iv_ogm.c:868 batadv_iv_send_outstanding_bat_ogm_packet+0x72d/0x840 net/batman-adv/bat_iv_ogm.c:1712 process_one_work+0x898/0x1160 kernel/workqueue.c:2292 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: rcu_preempt kthread timer wakeup didn't happen for 10546 jiffies! g19465 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=12565 rcu: rcu_preempt kthread starved for 10552 jiffies! g19465 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27008 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5244 [inline] __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561 schedule+0xb9/0x180 kernel/sched/core.c:6637 schedule_timeout+0x15c/0x280 kernel/time/timer.c:2167 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905 kthread+0x29d/0x330 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 PID: 6017 Comm: syz.3.356 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202 Code: f5 ff 0f 1f 00 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 8e 8f 41 f7 48 89 df e8 e6 54 42 f7 e8 31 48 65 f7 fb bf 01 00 00 00 76 cd 35 f7 65 8b 05 f7 84 e0 75 85 c0 74 02 5b c3 e8 44 96 de RSP: 0018:ffffc900032b7b98 EFLAGS: 00000282 RAX: 8c7009f4324be100 RBX: ffff8880542b1bc0 RCX: 8c7009f4324be100 RDX: dffffc0000000000 RSI: ffffffff8a8c0580 RDI: 0000000000000001 RBP: ffff8880542b1e58 R08: dffffc0000000000 R09: ffffed100a856379 R10: ffffed100a856379 R11: 1ffff1100a856378 R12: 1ffff1100a8563cb R13: 0000000000000011 R14: dffffc0000000000 R15: 0000000000000000 FS: 00007f39a5ca16c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f3d7a47c0a0 CR3: 000000007a343000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: spin_unlock_irq include/linux/spinlock.h:401 [inline] get_signal+0x1163/0x1350 kernel/signal.c:2874 arch_do_signal_or_restart+0xb7/0x1240 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f39a4d8f6c9 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:00007f39a5ca10e8 EFLAGS: 00000246 RAX: fffffffffffffffc RBX: 00007f39a4fe6188 RCX: 00007f39a4d8f6c9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f39a4fe6188 RBP: 00007f39a4fe6180 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f39a4fe6218 R14: 00007ffeb1a1a9f0 R15: 00007ffeb1a1aad8 sched: RT throttling activated hrtimer: interrupt took 960700126 ns