rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=e9ac/1/0x4000000000000000 softirq=53002/53004 fqs=2 rcu: (detected by 1, t=10502 jiffies, g=82505, q=557 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 14233 Comm: kworker/u4:18 Not tainted 6.6.0-rc5-syzkaller-01232-g85605fb694f0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:122 [inline] RIP: 0010:lock_release+0x133/0x680 kernel/locking/lockdep.c:5766 Code: 00 49 8d be c4 0a 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 <84> d2 0f 85 d9 04 00 00 41 8b b6 c4 0a 00 00 85 f6 0f 85 64 02 00 RSP: 0018:ffffc90000007d60 EFLAGS: 00000002 RAX: 0000000000000007 RBX: ffffffff8ece77d8 RCX: ffffffff81688cb5 RDX: 0000000000000000 RSI: ffffffff8ae93660 RDI: ffff88802088a884 RBP: 1ffff92000000fae R08: 0000000000000000 R09: fffffbfff1d9c84a R10: ffffffff8ece4257 R11: 0000000000000000 R12: ffff8880b982b958 R13: 178e238ed9829c00 R14: ffff888020889dc0 R15: ffffffff88665550 FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000555556655750 CR3: 000000000c976000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:149 [inline] _raw_spin_unlock_irqrestore+0x1a/0x70 kernel/locking/spinlock.c:194 __run_hrtimer kernel/time/hrtimer.c:1684 [inline] __hrtimer_run_queues+0x58b/0xc10 kernel/time/hrtimer.c:1752 hrtimer_interrupt+0x31b/0x800 kernel/time/hrtimer.c:1814 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1063 [inline] __sysvec_apic_timer_interrupt+0x105/0x3f0 arch/x86/kernel/apic/apic.c:1080 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1074 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:645 RIP: 0010:lock_acquire+0x1ef/0x510 kernel/locking/lockdep.c:5721 Code: c1 05 15 ed 99 7e 83 f8 01 0f 85 b0 02 00 00 9c 58 f6 c4 02 0f 85 9b 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:ffffc9000b387a98 EFLAGS: 00000206 RAX: dffffc0000000000 RBX: 1ffff92001670f55 RCX: 0000000000000001 RDX: 1ffff11004111510 RSI: ffffffff8a8cae20 RDI: ffffffff8ae936e0 RBP: 0000000000000200 R08: 0000000000000000 R09: fffffbfff233e3d0 R10: ffffffff919f1e87 R11: 000000003eebce57 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff8cbab360 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:303 [inline] rcu_read_lock include/linux/rcupdate.h:749 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:754 [inline] batadv_iv_ogm_schedule_buff+0x5ac/0x14f0 net/batman-adv/bat_iv_ogm.c:825 batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:868 [inline] batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:861 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0x31e/0x8c0 net/batman-adv/bat_iv_ogm.c:1712 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630 process_scheduled_works kernel/workqueue.c:2703 [inline] worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 rcu: rcu_preempt kthread starved for 10428 jiffies! g82505 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 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:27920 pid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0xee1/0x5a10 kernel/sched/core.c:6695 schedule+0xe7/0x1b0 kernel/sched/core.c:6771 schedule_timeout+0x157/0x2c0 kernel/time/timer.c:2167 rcu_gp_fqs_loop+0x1ec/0xa50 kernel/rcu/tree.c:1613 rcu_gp_kthread+0x249/0x380 kernel/rcu/tree.c:1812 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 PID: 5137 Comm: kworker/1:5 Not tainted 6.6.0-rc5-syzkaller-01232-g85605fb694f0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 Workqueue: events fqdir_free_fn RIP: 0010:csd_lock_wait kernel/smp.c:300 [inline] RIP: 0010:smp_call_function_single+0x1f0/0x650 kernel/smp.c:639 Code: de 89 fa c1 e2 10 09 d0 89 84 24 8c 00 00 00 e8 a6 fa ff ff 41 89 c5 0f 1f 44 00 00 e8 79 6e 0b 00 eb 07 e8 72 6e 0b 00 f3 90 <8b> 9c 24 88 00 00 00 31 ff 83 e3 01 89 de e8 cd 69 0b 00 85 db 75 RSP: 0018:ffffc9000453fb20 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff88807a845940 RSI: ffffffff817c621e RDI: 0000000000000005 RBP: ffffc9000453fc30 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: ffff8880b983d620 R12: 1ffff920008a7f68 R13: 0000000000000000 R14: 0000000000000001 R15: ffff8880b983d600 FS: 0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f560d977978 CR3: 000000004515f000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_barrier+0x284/0x6c0 kernel/rcu/tree.c:4053 fqdir_free_fn+0x32/0x160 net/ipv4/inet_fragment.c:164 process_one_work+0x884/0x15c0 kernel/workqueue.c:2630 process_scheduled_works kernel/workqueue.c:2703 [inline] worker_thread+0x8b9/0x1290 kernel/workqueue.c:2784 kthread+0x33c/0x440 kernel/kthread.c:388 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304