syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5874/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=9713, q=716 ncpus=2)
task:syz-executor    state:R  running task     stack:21736 pid:5874  ppid:5872   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+0x29b/0x3e0 net/batman-adv/hard-interface.c:526
 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:6472
 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: 0033:0x7f4c913915dc
RSP: 002b:00007ffd35e43880 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f4c92114620 RCX: 00007f4c913915dc
RDX: 000000000000002c RSI: 00007f4c92114670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffd35e438d4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f4c92114670 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread starved for 10550 jiffies! g9713 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:2168
 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: 5874 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:update_fast_timekeeper+0x0/0xa0 kernel/time/timekeeping.c:418
Code: 2c 0f 00 85 db 74 0e e8 de 28 0f 00 48 8b 05 f7 7c 77 15 5b c3 e8 d0 28 0f 00 5b e9 da 8a ed ff 66 2e 0f 1f 84 00 00 00 00 00 <41> 57 41 56 41 55 41 54 53 48 89 f3 49 89 ff 49 bc 00 00 00 00 00
RSP: 0018:ffffc90000007c38 EFLAGS: 00000046
RAX: 1ffffffff2ddbca6 RBX: 18835bc8231c2400 RCX: ffff888021a28000
RDX: 0000000000010000 RSI: ffffffff8cd49740 RDI: ffffffff96ede500
RBP: 0000000000000000 R08: ffffffff8e4a212f R09: 1ffffffff1c94425
R10: dffffc0000000000 R11: fffffbfff1c94426 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff96ede500 R15: 1ffffffff2ddbca5
FS:  0000555588ffb500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fec2f853e9c CR3: 0000000070b29000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 timekeeping_update+0x325/0x410 kernel/time/timekeeping.c:771
 timekeeping_advance+0x7ab/0xac0 kernel/time/timekeeping.c:2215
 update_wall_time+0x10/0x30 kernel/time/timekeeping.c:2231
 tick_sched_do_timer kernel/time/tick-sched.c:210 [inline]
 tick_sched_timer+0xcb/0x580 kernel/time/tick-sched.c:1485
 __run_hrtimer kernel/time/hrtimer.c:1750 [inline]
 __hrtimer_run_queues+0x4df/0xc40 kernel/time/hrtimer.c:1814
 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1876
 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:console_trylock_spinning kernel/printk/printk.c:2008 [inline]
RIP: 0010:vprintk_emit+0x44f/0x600 kernel/printk/printk.c:2340
Code: 51 01 00 00 e8 52 55 1b 00 45 89 f7 48 85 db 48 8b 5c 24 08 75 07 e8 40 55 1b 00 eb 06 e8 39 55 1b 00 fb 48 c7 c7 40 42 d2 8c <31> f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00 45 31 c9 53 e8 59 bd
RSP: 0018:ffffc90003246a20 EFLAGS: 00000293
RAX: ffffffff816a3b87 RBX: ffffffff816a3a41 RCX: ffff888021a28000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8cd24240
RBP: ffffc90003246b10 R08: ffffffff90d945c7 R09: 1ffffffff21b28b8
R10: dffffc0000000000 R11: fffffbfff21b28b9 R12: dffffc0000000000
R13: ffffc90003246b80 R14: 0000000000000056 R15: 0000000000000056
 _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:6472
 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: 0033:0x7f4c913915dc
Code: 2a 5f 02 00 44 8b 4c 24 2c 4c 8b 44 24 20 89 c5 44 8b 54 24 28 48 8b 54 24 18 b8 2c 00 00 00 48 8b 74 24 10 8b 7c 24 08 0f 05 <48> 3d 00 f0 ff ff 77 34 89 ef 48 89 44 24 08 e8 70 5f 02 00 48 8b
RSP: 002b:00007ffd35e43880 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f4c92114620 RCX: 00007f4c913915dc
RDX: 000000000000002c RSI: 00007f4c92114670 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007ffd35e438d4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 0000000000000000 R14: 00007f4c92114670 R15: 0000000000000000
 </TASK>