syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3016/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=11757, q=305 ncpus=2)
task:kworker/u8:8    state:R  running task     stack:25904 pid:3016  tgid:3016  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5188 [inline]
 __schedule+0xe37/0x5490 kernel/sched/core.c:6529
 preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:6851
 irqentry_exit+0x36/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x1f2/0x560 kernel/locking/lockdep.c:5727
Code: c1 05 ea b0 98 7e 83 f8 01 0f 85 ea 02 00 00 9c 58 f6 c4 02 0f 85 d5 02 00 00 48 85 ed 74 01 fb 48 b8 00 00 00 00 00 fc ff df <48> 01 c3 48 c7 03 00 00 00 00 48 c7 43 08 00 00 00 00 48 8b 84 24
RSP: 0018:ffffc900096f7a30 EFLAGS: 00000206
RAX: dffffc0000000000 RBX: 1ffff920012def48 RCX: 0000000000000001
RDX: 0000000000000001 RSI: ffffffff8b4cddc0 RDI: ffffffff8bb118a0
RBP: 0000000000000200 R08: 0000000000000000 R09: fffffbfff2d39ae0
R10: ffffffff969cd707 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff8ddba6a0 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:326 [inline]
 rcu_read_lock include/linux/rcupdate.h:838 [inline]
 batadv_nc_process_nc_paths.part.0+0xe4/0x3e0 net/batman-adv/network-coding.c:687
 batadv_nc_process_nc_paths net/batman-adv/network-coding.c:679 [inline]
 batadv_nc_worker+0xcc8/0x1060 net/batman-adv/network-coding.c:728
 process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
 process_scheduled_works kernel/workqueue.c:3312 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3393
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: rcu_preempt kthread starved for 10531 jiffies! g11757 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:28640 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5188 [inline]
 __schedule+0xe37/0x5490 kernel/sched/core.c:6529
 __schedule_loop kernel/sched/core.c:6606 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6621
 schedule_timeout+0x136/0x2a0 kernel/time/timer.c:2581
 rcu_gp_fqs_loop+0x1eb/0xb00 kernel/rcu/tree.c:2034
 rcu_gp_kthread+0x271/0x380 kernel/rcu/tree.c:2236
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </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 UID: 0 PID: 5310 Comm: syz-executor383 Not tainted 6.11.0-syzkaller-02574-ga430d95c5efa #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:__sanitizer_cov_trace_cmp8+0x8/0x20 kernel/kcov.c:292
Code: 00 00 00 e9 ea fe ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 0c 24 <48> 89 f2 48 89 fe bf 06 00 00 00 e9 b8 fe ff ff 0f 1f 84 00 00 00
RSP: 0018:ffffc90004027af8 EFLAGS: 00000082
RAX: 0000000000000000 RBX: 000000000204b05b RCX: ffffffff8179a243
RDX: ffff88802b069e00 RSI: 1fffffffffffffff RDI: fffffffffdfb4fa4
RBP: ffffffff8dde67b8 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1fffffffffffffff
R13: fffffffffdfb4fa4 R14: ffffffffffffffff R15: ffffffff8dde67c0
FS:  000055558ee073c0(0000) GS:ffff8880b8800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002006b000 CR3: 00000000405b4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 timekeeping_debug_get_ns+0x363/0x5b0 kernel/time/timekeeping.c:269
 timekeeping_get_ns kernel/time/timekeeping.c:401 [inline]
 ktime_get+0xd9/0x1a0 kernel/time/timekeeping.c:850
 common_hrtimer_rearm+0x96/0x180 kernel/time/posix-timers.c:247
 posixtimer_rearm+0x1ee/0x360 kernel/time/posix-timers.c:267
 dequeue_signal+0x2ac/0x660 kernel/signal.c:696
 get_signal+0x5fb/0x2770 kernel/signal.c:2796
 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218
 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f83cb67e59a
Code: 48 3d 00 f0 ff ff 77 48 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 7c 24 0c e8 33 87 02 00 8b 7c 24 0c 89 c2 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 36 89 d7 89 44 24 0c e8 93 87 02 00 8b 44 24
RSP: 002b:00007fff50709490 EFLAGS: 00000293
RAX: fffffffffffffff7 RBX: 0000000000000004 RCX: 00007f83cb67e59a
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000000 R08: 00007fff50709010 R09: 00007fff50709010
R10: 0000000000000000 R11: 0000000000000293 R12: 00007f83cb6d6036
R13: 00007fff507094e0 R14: 00007fff50709520 R15: 0000000000000000
 </TASK>
sched: RT throttling activated