syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5923/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=10741, q=662 ncpus=2)
task:syz-executor    state:R  running task     stack:21544 pid:5923  ppid:5915   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866
 preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 vprintk_emit+0x578/0x600 kernel/printk/printk.c:2342
 _printk+0xd0/0x110 kernel/printk/printk.c:2366
 batadv_check_known_mac_addr+0x2a7/0x3e0 net/batman-adv/hard-interface.c:528
 batadv_hard_if_event+0x3a3/0x15b0 net/batman-adv/hard-interface.c:998
 notifier_call_chain+0x197/0x390 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
 call_netdevice_notifiers net/core/dev.c:2078 [inline]
 dev_set_mac_address+0x377/0x4b0 net/core/dev.c:8948
 dev_set_mac_address_user+0x31/0x50 net/core/dev.c:8962
 do_setlink+0x871/0x3fb0 net/core/rtnetlink.c:2860
 __rtnl_newlink net/core/rtnetlink.c:3703 [inline]
 rtnl_newlink+0x175b/0x2020 net/core/rtnetlink.c:3750
 rtnetlink_rcv_msg+0x7c7/0xf10 net/core/rtnetlink.c:6475
 netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x46a/0x620 net/socket.c:2201
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2209
 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: 0033:0x7f1e9dd90a7c
RSP: 002b:00007ffe05870940 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f1e9eaf4620 RCX: 00007f1e9dd90a7c
RDX: 000000000000002c RSI: 00007f1e9eaf4670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffe05870994 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f1e9eaf4670 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10553 jiffies! g10741 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:27752 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 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
 </TASK>
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: 6027 Comm: syz.3.20 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:hlock_class kernel/locking/lockdep.c:228 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4774 [inline]
RIP: 0010:__lock_acquire+0x619/0x7c80 kernel/locking/lockdep.c:5087
Code: 07 89 c3 81 e3 ff 1f 00 00 c1 e8 03 25 f8 03 00 00 48 8d b8 00 55 da 90 be 08 00 00 00 e8 ff cb 75 00 48 0f a3 1d 57 49 73 0f <73> 1a 48 69 c3 d0 00 00 00 48 8d 98 c0 d3 70 90 49 b8 00 00 00 00
RSP: 0018:ffffc90000007880 EFLAGS: 00000057
RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffffffff81670ba1
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90da5500
RBP: ffffc90000007ac8 R08: ffffffff90da5507 R09: 1ffffffff21b4aa0
R10: dffffc0000000000 R11: fffffbfff21b4aa1 R12: ffff88807d1046c4
R13: ffff88807d103c00 R14: 0000000000000002 R15: ffff88807d104728
FS:  0000555576509500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000006b000 CR3: 000000002566d000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162
 debug_object_deactivate+0x67/0x350 lib/debugobjects.c:764
 debug_hrtimer_deactivate kernel/time/hrtimer.c:455 [inline]
 debug_deactivate+0x1d/0x1d0 kernel/time/hrtimer.c:511
 __run_hrtimer kernel/time/hrtimer.c:1723 [inline]
 __hrtimer_run_queues+0x2bf/0xc40 kernel/time/hrtimer.c:1819
 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1881
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202
Code: 00 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 4a e0 ef f6 48 89 df e8 62 b2 f0 f6 e8 1d 51 14 f7 fb bf 01 00 00 00 <e8> b2 c9 e3 f6 65 8b 05 23 18 8c 75 85 c0 74 02 5b c3 e8 00 fa 88
RSP: 0018:ffffc90003657c98 EFLAGS: 00000282
RAX: d2d74677ecd48500 RBX: ffff8880568eae40 RCX: d2d74677ecd48500
RDX: dffffc0000000000 RSI: ffffffff8aaaba20 RDI: 0000000000000001
RBP: ffff8880568eb2d8 R08: ffffffff8e4a8f2f R09: 1ffffffff1c951e5
R10: dffffc0000000000 R11: fffffbfff1c951e6 R12: 1ffff1100ad1d65b
R13: 0000000000000021 R14: dffffc0000000000 R15: 0000000000000000
 spin_unlock_irq include/linux/spinlock.h:401 [inline]
 get_signal+0x11f5/0x1400 kernel/signal.c:2905
 arch_do_signal_or_restart+0x96/0x780 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 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: 0033:0x7f062878ebe9
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:00007ffdc4685998 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 00007f06289c5fa0 RCX: 00007f062878ebe9
RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f0628811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f06289c5fa0 R14: 00007f06289c5fa0 R15: 0000000000000004
 </TASK>
sched: RT throttling activated