rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P256/1:b..l (detected by 1, t=10502 jiffies, g=253941, q=57) task:kworker/u4:3 state:R running task stack:23336 pid: 256 ppid: 2 flags:0x00004000 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb44/0x5960 kernel/sched/core.c:6287 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:6687 irqentry_exit+0x31/0x80 kernel/entry/common.c:425 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:lock_acquire+0x1ef/0x510 kernel/locking/lockdep.c:5593 Code: c7 a5 7e 83 f8 01 0f 85 b4 02 00 00 9c 58 f6 c4 02 0f 85 9f 02 00 00 48 83 7c 24 08 00 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:ffffc9000204faa8 EFLAGS: 00000206 RAX: dffffc0000000000 RBX: 1ffff92000409f57 RCX: 416a3ee2184ed825 RDX: 1ffff11002f72bf3 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8fcff9e7 R10: fffffbfff1f9ff3c R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: ffffffff8b981b60 R15: 0000000000000000 rcu_lock_acquire include/linux/rcupdate.h:267 [inline] rcu_read_lock include/linux/rcupdate.h:687 [inline] batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:755 [inline] batadv_iv_ogm_schedule_buff+0x5d2/0x1430 net/batman-adv/bat_iv_ogm.c:826 batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:869 [inline] batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:862 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0x740/0x8e0 net/batman-adv/bat_iv_ogm.c:1713 process_one_work+0x9bf/0x16b0 kernel/workqueue.c:2297 worker_thread+0x658/0x11f0 kernel/workqueue.c:2444 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: rcu_preempt kthread starved for 10502 jiffies! g253941 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:28696 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb44/0x5960 kernel/sched/core.c:6287 schedule+0xd3/0x270 kernel/sched/core.c:6366 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x800 kernel/rcu/tree.c:1957 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2130 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 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: 3688 Comm: syz-executor.1 Not tainted 5.15.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__lock_acquire+0xe5e/0x54a0 kernel/locking/lockdep.c:5042 Code: 8b 5c 24 30 48 c7 04 03 00 00 00 00 48 8b 84 24 e0 00 00 00 65 48 2b 04 25 28 00 00 00 0f 85 1e 2f 00 00 48 81 c4 e8 00 00 00 <44> 89 f0 5b 5d 41 5c 41 5d 41 5e 41 5f c3 e8 0f ac 7b 02 85 c0 0f RSP: 0018:ffffc90000007aa8 EFLAGS: 00000082 RAX: 0000000000000000 RBX: 1ffff92000000f49 RCX: ffffffff815bdf9f RDX: 1ffff110036b4143 RSI: 0000000000000001 RDI: ffffffff8f048538 RBP: 00000000000019a1 R08: 0000000000000000 R09: ffffffff8fcff9ef R10: fffffbfff1f9ff3d R11: 0000000000000000 R12: ffff88801b5a0a20 R13: ffff88801b5a0000 R14: 0000000000000001 R15: b20fbda6538c2b94 FS: 00007f352d782700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f352d740718 CR3: 000000005ca6a000 CR4: 0000000000350ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 seqcount_lockdep_reader_access include/linux/seqlock.h:103 [inline] timekeeping_get_delta kernel/time/timekeeping.c:252 [inline] timekeeping_get_ns kernel/time/timekeeping.c:386 [inline] ktime_get+0x147/0x470 kernel/time/timekeeping.c:829 hrtimer_forward_now include/linux/hrtimer.h:506 [inline] perf_swevent_hrtimer+0x246/0x3f0 kernel/events/core.c:10572 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:__schedule+0xb4c/0x5960 kernel/sched/core.c:6166 Code: fa 48 c1 ea 03 80 3c 02 00 0f 85 70 4a 00 00 48 8b bd 40 ff ff ff 4c 89 63 10 4c 89 e6 e8 0c 9c c8 f7 48 89 c7 e8 d4 88 18 f8 <48> 8b b5 e8 fe ff ff 48 b8 00 00 00 00 00 fc ff df 48 c7 04 06 00 RSP: 0018:ffffc9000ccef738 EFLAGS: 00000202 RAX: 0000000000ea4573 RBX: 0000000000000001 RCX: 1ffffffff1adcad9 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000ccef888 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff817d01e8 R11: 0000000000000000 R12: ffff8880b9c32500 R13: 0000000000000000 R14: ffffffff8b332cc0 R15: ffffffff8b332cc0 schedule+0xd3/0x270 kernel/sched/core.c:6366 tty_open+0x885/0x1000 drivers/tty/tty_io.c:2153 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x4c8/0x11d0 fs/open.c:822 do_open fs/namei.c:3428 [inline] path_openat+0x1c9a/0x2740 fs/namei.c:3561 do_filp_open+0x1aa/0x400 fs/namei.c:3588 do_sys_openat2+0x16d/0x4d0 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_openat fs/open.c:1232 [inline] __se_sys_openat fs/open.c:1227 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f353020ca39 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f352d782188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f353030ff60 RCX: 00007f353020ca39 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f3530266c5f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd1a0160cf R14: 00007f352d782300 R15: 0000000000022000 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: a5 movsl %ds:(%rsi),%es:(%rdi) 1: 7e 83 jle 0xffffff86 3: f8 clc 4: 01 0f add %ecx,(%rdi) 6: 85 b4 02 00 00 9c 58 test %esi,0x589c0000(%rdx,%rax,1) d: f6 c4 02 test $0x2,%ah 10: 0f 85 9f 02 00 00 jne 0x2b5 16: 48 83 7c 24 08 00 cmpq $0x0,0x8(%rsp) 1c: 74 01 je 0x1f 1e: fb sti 1f: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 26: fc ff df * 29: 48 01 c3 add %rax,%rbx <-- trapping instruction 2c: 48 c7 03 00 00 00 00 movq $0x0,(%rbx) 33: 48 c7 43 08 00 00 00 movq $0x0,0x8(%rbx) 3a: 00 3b: 48 rex.W 3c: 8b .byte 0x8b 3d: 84 .byte 0x84 3e: 24 .byte 0x24