rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (1 GPs behind) idle=dd34/1/0x4000000000000000 softirq=18537/18546 fqs=0 rcu: (detected by 0, t=10502 jiffies, g=18921, q=1624 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 57 Comm: kworker/u8:4 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Workqueue: events_unbound cfg80211_wiphy_work RIP: 0010:rcu_is_watching+0x67/0xb0 kernel/rcu/tree.c:753 Code: 89 f7 e8 dc a8 88 00 48 c7 c3 d8 98 6d 93 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 84 c0 75 34 8b 03 65 ff 0d 99 12 c1 11 <74> 11 83 e0 04 c1 e8 02 5b 41 5e 41 5f c3 cc cc cc cc cc e8 91 21 RSP: 0018:ffffc90000a08db8 EFLAGS: 00000006 RAX: 000000000001dd34 RBX: ffff8880b87338d8 RCX: 0000000000010001 RDX: ffff88801b149f00 RSI: ffffffff8c4bd260 RDI: ffffffff8c4bd220 RBP: ffff88807fa4e300 R08: ffffffff90576df7 R09: 1ffffffff20aedbe R10: dffffc0000000000 R11: fffffbfff20aedbf R12: 0000000000000001 R13: 0000000000000001 R14: ffffffff8e4f77d8 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff88812505a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fdaa0d5da08 CR3: 000000006f9c0000 CR4: 00000000003526f0 Call Trace: trace_hrtimer_expire_exit include/trace/events/timer.h:321 [inline] __run_hrtimer kernel/time/hrtimer.c:2035 [inline] __hrtimer_run_queues+0x440/0xa10 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x448/0x910 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:lock_release+0x2d7/0x3c0 kernel/locking/lockdep.c:5893 Code: 4e ca 11 00 00 00 00 eb b5 e8 a5 fe 2b 0a f7 c3 00 02 00 00 74 b9 65 48 8b 05 95 09 ca 11 48 3b 44 24 28 75 44 fb 48 83 c4 30 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc 48 8d 3d 52 a8 b8 RSP: 0018:ffffc900015e7548 EFLAGS: 00000286 RAX: 39da5761f1caae00 RBX: 0000000000000206 RCX: 0000000000000046 RDX: 0000000000000003 RSI: ffffffff8e4aea3e RDI: ffffffff8c4bd280 RBP: ffff88801b14ab18 R08: ffffc900015e7e70 R09: 0000000000000000 R10: ffffc900015e7678 R11: fffff520002bced1 R12: 0000000000000003 R13: 0000000000000003 R14: ffffffff8eb59c20 R15: ffff88801b149f00 rcu_lock_release include/linux/rcupdate.h:310 [inline] rcu_read_unlock include/linux/rcupdate.h:871 [inline] class_rcu_destructor include/linux/rcupdate.h:1183 [inline] unwind_next_frame+0x1baa/0x2550 arch/x86/kernel/unwind_orc.c:709 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2705 [inline] slab_free mm/slub.c:6405 [inline] kmem_cache_free+0x182/0x650 mm/slub.c:6532 ieee80211_iface_work+0x259/0x1010 net/mac80211/iface.c:1819 cfg80211_wiphy_work+0x29e/0x420 net/wireless/core.c:538 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: rcu_preempt kthread starved for 10502 jiffies! g18921 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:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7326 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2325 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 0 UID: 0 PID: 5287 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_many_cond+0x10b0/0x14b0 kernel/smp.c:892 Code: c0 75 73 41 8b 1e 89 de 83 e6 01 31 ff e8 d8 1e 0c 00 83 e3 01 48 bb 00 00 00 00 00 fc ff df 75 07 e8 84 1a 0c 00 eb 37 f3 90 <41> 0f b6 04 1c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e e8 69 1a 0c RSP: 0018:ffffc9000349f580 EFLAGS: 00000293 RAX: ffffffff81ba5757 RBX: dffffc0000000000 RCX: ffff888026919f00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000349f6a8 R08: ffffffff90576df7 R09: 1ffffffff20aedbe R10: dffffc0000000000 R11: fffffbfff20aedbf R12: 1ffff110170e81d1 R13: ffff8880b863c448 R14: ffff8880b8740e88 R15: 0000000000000001 FS: 00007f1aaca89780(0000) GS:ffff888124f5a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00005654dad8c1b0 CR3: 0000000076e1a000 CR4: 00000000003526f0 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057 __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x5c4/0x1090 arch/x86/mm/tlb.c:1451 dup_mmap+0x1786/0x1d90 mm/mmap.c:1905 dup_mm kernel/fork.c:1538 [inline] copy_mm+0x11a/0x480 kernel/fork.c:1590 copy_process+0x1e99/0x43f0 kernel/fork.c:2288 kernel_clone+0x2d7/0x940 kernel/fork.c:2747 __do_sys_clone kernel/fork.c:2888 [inline] __se_sys_clone kernel/fork.c:2872 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2872 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1aacb5d636 Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffdd1be3be0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffdd1be3be8 RCX: 00007f1aacb5d636 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 00007ffdd1c04130 R08: 0000000000000000 R09: 0000000000000001 R10: 00007f1aaca89a50 R11: 0000000000000246 R12: 00007ffdd1be3d20 R13: 0000000000000000 R14: 0000000000000000 R15: 000055d290a3eac0