rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P30614/1:b..l P5965/1:b..l rcu: (detected by 0, t=10502 jiffies, g=233273, q=337 ncpus=2) task:kworker/u4:9 state:R running task stack:21800 pid:5965 ppid:2 flags:0x00004000 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x14e2/0x4580 kernel/sched/core.c:6700 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7010 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:lock_acquire+0x2b/0x410 kernel/locking/lockdep.c:5722 Code: 0f 1e fa 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec e0 00 00 00 4c 89 4c 24 28 4c 89 44 24 30 48 89 4c 24 20 <89> d3 89 74 24 1c 49 89 fd 65 48 8b 04 25 28 00 00 00 48 89 84 24 RSP: 0018:ffffc900050178a0 EFLAGS: 00000286 RAX: ffffffff8a29fe33 RBX: ffff88802e1d50a0 RCX: 0000000000000002 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8cd2f760 RBP: ffffc900050179a8 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: fffffbfff1c934ee R12: dffffc0000000000 R13: dffffc0000000000 R14: 0000000000000001 R15: ffff88805cf1b8a4 rcu_lock_acquire include/linux/rcupdate.h:334 [inline] rcu_read_lock include/linux/rcupdate.h:786 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:753 [inline] batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:824 [inline] batadv_iv_ogm_schedule+0x417/0xe90 net/batman-adv/bat_iv_ogm.c:867 batadv_iv_send_outstanding_bat_ogm_packet+0x731/0x840 net/batman-adv/bat_iv_ogm.c:1711 process_one_work kernel/workqueue.c:2634 [inline] process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792 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 task:syz.1.7689 state:R running task stack:24744 pid:30614 ppid:29001 flags:0x00004006 Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x14e2/0x4580 kernel/sched/core.c:6700 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867 preempt_schedule+0xab/0xc0 kernel/sched/core.c:6891 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0xfa/0x110 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] __wake_up_common_lock kernel/sched/wait.c:140 [inline] __wake_up_sync_key+0x11f/0x190 kernel/sched/wait.c:213 unix_write_space+0x1ff/0x370 net/unix/af_unix.c:540 sock_wfree+0x1a0/0x610 net/core/sock.c:2496 unix_destruct_scm+0x151/0x190 net/unix/af_unix.c:1813 skb_release_head_state+0xfa/0x240 net/core/skbuff.c:1039 skb_release_all net/core/skbuff.c:1051 [inline] __kfree_skb net/core/skbuff.c:1067 [inline] consume_skb+0x7b/0x110 net/core/skbuff.c:1283 unix_stream_read_generic+0x1b01/0x2080 net/unix/af_unix.c:2847 unix_stream_recvmsg+0x158/0x1b0 net/unix/af_unix.c:2926 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 do_recvmmsg+0x360/0x7d0 net/socket.c:2950 __sys_recvmmsg net/socket.c:3029 [inline] __do_sys_recvmmsg net/socket.c:3052 [inline] __se_sys_recvmmsg net/socket.c:3045 [inline] __x64_sys_recvmmsg+0x191/0x240 net/socket.c:3045 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: 0033:0x7f833e38e929 RSP: 002b:00007f833f173038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007f833e5b6080 RCX: 00007f833e38e929 RDX: 040000000000013c RSI: 00002000000034c0 RDI: 0000000000000006 RBP: 00007f833e410b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000700 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f833e5b6080 R15: 00007fff3c817d28 rcu: rcu_preempt kthread starved for 10548 jiffies! g233273 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:27304 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5381 [inline] __schedule+0x14e2/0x4580 kernel/sched/core.c:6700 schedule+0xbd/0x170 kernel/sched/core.c:6774 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1663 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1862 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: 0 Comm: swapper/0 Not tainted 6.6.93-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 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 63 10 42 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:ffffffff8ca07d80 EFLAGS: 000002c2 RAX: 0a05bc9734c9f300 RBX: ffffffff81618a7b RCX: 0a05bc9734c9f300 RDX: 0000000000000001 RSI: ffffffff8aaab2c0 RDI: ffffffff8afc6780 RBP: ffffffff8ca07eb8 R08: ffff8880b8e36d4b R09: 1ffff110171c6da9 R10: dffffc0000000000 R11: ffffed10171c6daa R12: ffffffff8e49a768 R13: 0000000000000000 R14: 0000000000000000 R15: 1ffffffff1952670 FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00002000000d0000 CR3: 0000000025f24000 CR4: 00000000003506f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline] default_idle+0x13/0x20 arch/x86/kernel/process.c:747 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97 cpuidle_idle_call kernel/sched/idle.c:170 [inline] do_idle+0x1eb/0x510 kernel/sched/idle.c:282 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380 rest_init+0x2e2/0x300 init/main.c:732 arch_call_rest_init+0xe/0x10 init/main.c:829 start_kernel+0x459/0x4e0 init/main.c:1074 x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555 x86_64_start_kernel+0x60/0x60 arch/x86/kernel/head64.c:536 secondary_startup_64_no_verify+0x179/0x17b