rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P3973/1:b..l (detected by 0, t=10503 jiffies, g=319745, q=11) task:kworker/u4:10 state:R running task stack:20912 pid: 3973 ppid: 2 flags:0x00004000 Workqueue: bat_events batadv_nc_worker Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb72/0x1460 kernel/sched/core.c:6287 preempt_schedule_notrace+0x14d/0x190 kernel/sched/core.c:6538 preempt_schedule_notrace_thunk+0x16/0x18 rcu_read_unlock_sched_notrace include/linux/rcupdate.h:809 [inline] trace_lock_acquire+0xb4/0x190 include/trace/events/lock.h:13 lock_acquire+0xa5/0x4d0 kernel/locking/lockdep.c:5596 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:267 rcu_read_lock include/linux/rcupdate.h:687 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:410 [inline] batadv_nc_worker+0xc8/0x5b0 net/batman-adv/network-coding.c:721 process_one_work+0x853/0x1140 kernel/workqueue.c:2297 worker_thread+0xac1/0x1320 kernel/workqueue.c:2444 kthread+0x453/0x480 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 rcu: rcu_preempt kthread starved for 10517 jiffies! g319745 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:26544 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb72/0x1460 kernel/sched/core.c:6287 schedule+0x14b/0x210 kernel/sched/core.c:6366 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x1fd/0x770 kernel/rcu/tree.c:1957 rcu_gp_kthread+0xa5/0x350 kernel/rcu/tree.c:2130 kthread+0x453/0x480 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 9787 Comm: syz-executor.2 Not tainted 5.15.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:validate_chain+0xc/0x8240 kernel/locking/lockdep.c:3745 Code: 03 38 c1 7c 81 48 c7 c7 98 3f dc 8d e8 bd 04 69 00 e9 70 ff ff ff e8 93 72 94 08 0f 1f 00 55 48 89 e5 41 57 41 56 41 55 41 54 <53> 48 83 e4 e0 48 81 ec e0 02 00 00 49 89 ce 89 54 24 68 48 89 bc RSP: 0018:ffffc90000dc0a50 EFLAGS: 00000086 RAX: 1ffffffff1eccb94 RBX: 0000000000000042 RCX: e5500d0ab0c7259c RDX: 0000000000000000 RSI: ffff88806d480a48 RDI: ffff88806d480000 RBP: ffffc90000dc0a70 R08: dffffc0000000000 R09: fffffbfff1fa37da R10: fffffbfff1fa37da R11: 0000000000000000 R12: ffff88806d480000 R13: ffff88806d480a48 R14: ffffffff8f665ca0 R15: e5500d0ab0c7259c FS: 00007fae29d30700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb27c00d004 CR3: 000000007879b000 CR4: 00000000003506e0 Call Trace: __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5015 lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625 seqcount_lockdep_reader_access+0xfe/0x230 include/linux/seqlock.h:103 ktime_get_update_offsets_now+0x45/0x460 kernel/time/timekeeping.c:2297 hrtimer_update_base kernel/time/hrtimer.c:631 [inline] hrtimer_interrupt+0x143/0x1040 kernel/time/hrtimer.c:1793 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0xf9/0x270 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0010:rcu_lockdep_current_cpu_online+0x53/0x130 kernel/rcu/tree.c:1169 Code: 65 83 05 57 e6 93 7e 01 e8 ba 6f 8c 08 89 c3 83 f8 08 0f 83 cd 00 00 00 49 bf 00 00 00 00 00 fc ff df 48 8d 1c dd d0 b7 38 8c <48> 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 f7 ee 60 00 RSP: 0018:ffffc9000b23f4f8 EFLAGS: 00000297 RAX: 0000000000000001 RBX: ffffffff8c38b7d8 RCX: 0000000080000001 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000 RBP: ffffc9000b23f5a8 R08: dffffc0000000000 R09: ffffed10173a64a2 R10: ffffed10173a64a2 R11: 0000000000000000 R12: ffff8880352def00 R13: dffffc0000000000 R14: dffffc0000000000 R15: dffffc0000000000 rcu_read_lock_held_common kernel/rcu/update.c:112 [inline] rcu_read_lock_sched_held+0x74/0x130 kernel/rcu/update.c:123 trace_kfree+0x2e/0xd0 include/trace/events/kmem.h:118 kfree+0x2f/0x310 mm/slub.c:4542 tty_free_file drivers/tty/tty_io.c:220 [inline] tty_open+0x907/0xdd0 drivers/tty/tty_io.c:2149 chrdev_open+0x5fb/0x680 fs/char_dev.c:414 do_dentry_open+0x7cb/0x1020 fs/open.c:822 do_open fs/namei.c:3428 [inline] path_openat+0x28b4/0x3670 fs/namei.c:3561 do_filp_open+0x277/0x4f0 fs/namei.c:3588 do_sys_openat2+0x13b/0x500 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+0x243/0x290 fs/open.c:1227 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fae2c7baa39 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:00007fae29d30188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fae2c8bdf60 RCX: 00007fae2c7baa39 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007fae2c814c5f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fffd0e3730f R14: 00007fae29d30300 R15: 0000000000022000 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 38 c1 cmp %al,%cl 2: 7c 81 jl 0xffffff85 4: 48 c7 c7 98 3f dc 8d mov $0xffffffff8ddc3f98,%rdi b: e8 bd 04 69 00 callq 0x6904cd 10: e9 70 ff ff ff jmpq 0xffffff85 15: e8 93 72 94 08 callq 0x89472ad 1a: 0f 1f 00 nopl (%rax) 1d: 55 push %rbp 1e: 48 89 e5 mov %rsp,%rbp 21: 41 57 push %r15 23: 41 56 push %r14 25: 41 55 push %r13 27: 41 54 push %r12 * 29: 53 push %rbx <-- trapping instruction 2a: 48 83 e4 e0 and $0xffffffffffffffe0,%rsp 2e: 48 81 ec e0 02 00 00 sub $0x2e0,%rsp 35: 49 89 ce mov %rcx,%r14 38: 89 54 24 68 mov %edx,0x68(%rsp) 3c: 48 rex.W 3d: 89 .byte 0x89 3e: bc .byte 0xbc