syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9/1:b..l P1126/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=18909, q=606 ncpus=2)
task:kworker/u4:7    state:R  running task     stack:21192 pid:1126  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:692
RIP: 0010:debug_lockdep_rcu_enabled+0x2c/0x30 kernel/rcu/update.c:319
Code: 1e fa 31 c0 83 3d 9f c8 db 03 00 74 1d 83 3d 16 fc db 03 00 74 14 65 48 8b 0d f0 f3 94 75 31 c0 83 b9 dc 0a 00 00 00 0f 94 c0 <c3> cc cc cc 66 0f 1f 00 48 8b 3c 24 e8 43 fb ff ff 66 90 66 90 e9
RSP: 0018:ffffc9000469fb58 EFLAGS: 00000246
RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffff88802331da00
RDX: 0000000000000000 RSI: ffffffff8afc6a60 RDI: ffffffff8afc6a20
RBP: fffffffffffffe38 R08: dffffc0000000000 R09: 1ffffffff21b50a0
R10: dffffc0000000000 R11: fffffbfff21b50a1 R12: dffffc0000000000
R13: ffffffff8a3700d2 R14: ffff88807f7b4c80 R15: 00000000000001d8
 rcu_read_unlock include/linux/rcupdate.h:815 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:412 [inline]
 batadv_nc_worker+0x1f4/0x610 net/batman-adv/network-coding.c:719
 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>
task:kworker/0:1     state:R  running task     stack:24616 pid:9     ppid:2      flags:0x00004000
Workqueue: events_power_efficient gc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009
 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+0x1f2/0x410 kernel/locking/lockdep.c:5758
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 66 43 c7 44 3c 09 00 00 43 c6 44 3c 0b 00
RSP: 0018:ffffc900000e7940 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 34401e732562e700
RDX: 0000000000000000 RSI: ffffffff8aaacee0 RDI: ffffffff8afc6a80
RBP: ffffc900000e7a48 R08: dffffc0000000000 R09: 1ffffffff21b50a0
R10: dffffc0000000000 R11: fffffbfff21b50a1 R12: 1ffff9200001cf34
R13: ffffffff8cd2ff20 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 rcu_read_lock include/linux/rcupdate.h:786 [inline]
 gc_worker+0x28d/0x14b0 net/netfilter/nf_conntrack_core.c:1502
 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>
rcu: rcu_preempt kthread starved for 10538 jiffies! g18909 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:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:finish_task_switch+0x26a/0x920 kernel/sched/core.c:5254
Code: 0f 84 37 01 00 00 48 85 db 0f 85 56 01 00 00 e9 f6 04 00 00 4c 8b 75 d0 4c 89 e7 e8 70 15 1c 09 e8 0b a3 2f 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffffff8ca07b18 EFLAGS: 00000286
RAX: 2bd14f7a85da0400 RBX: 0000000000000000 RCX: 2bd14f7a85da0400
RDX: dffffc0000000000 RSI: ffffffff8aaabd60 RDI: ffffffff8afc6a80
RBP: ffffffff8ca07b70 R08: ffffffff8e4a8b2f R09: 1ffffffff1c95165
R10: dffffc0000000000 R11: fffffbfff1c95166 R12: ffffffff8ca93440
R13: dffffc0000000000 R14: ffff88805e5c1e00 R15: ffff8880b8e3ccc8
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6d971e6098 CR3: 000000005ba4d000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5383 [inline]
 __schedule+0x14da/0x44d0 kernel/sched/core.c:6699
 schedule_idle+0x4e/0x80 kernel/sched/core.c:6801
 do_idle+0x4ac/0x510 kernel/sched/idle.c:310
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:380
 rest_init+0x2e2/0x300 init/main.c:744
 arch_call_rest_init+0xe/0x10 init/main.c:841
 start_kernel+0x459/0x4e0 init/main.c:1086
 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
 </TASK>