================================================================== BUG: KCSAN: data-race in wq_worker_tick / wq_worker_tick read-write to 0xffff8881000c5cd8 of 8 bytes by interrupt on cpu 1: wq_worker_tick+0x64/0x240 kernel/workqueue.c:1508 sched_tick+0xbc/0x1f0 kernel/sched/core.c:5804 update_process_times+0x15e/0x190 kernel/time/timer.c:2480 tick_sched_handle kernel/time/tick-sched.c:296 [inline] tick_nohz_handler+0x227/0x380 kernel/time/tick-sched.c:317 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x257/0x810 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 __orc_find arch/x86/kernel/unwind_orc.c:101 [inline] orc_find arch/x86/kernel/unwind_orc.c:238 [inline] unwind_next_frame+0x13f/0xd40 arch/x86/kernel/unwind_orc.c:510 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x91/0xd0 kernel/stacktrace.c:122 ref_tracker_free+0x94/0x3f0 lib/ref_tracker.c:306 netdev_tracker_free include/linux/netdevice.h:4519 [inline] netdev_put include/linux/netdevice.h:4536 [inline] dst_destroy+0x9e/0x330 net/core/dst.c:115 dst_destroy_rcu+0x19/0x20 net/core/dst.c:133 rcu_do_batch kernel/rcu/tree.c:2645 [inline] rcu_core+0x429/0x9d0 kernel/rcu/tree.c:2897 rcu_core_si+0xd/0x20 kernel/rcu/tree.c:2914 handle_softirqs+0xb9/0x280 kernel/softirq.c:622 do_softirq+0x45/0x60 kernel/softirq.c:523 __local_bh_enable_ip+0x70/0x80 kernel/softirq.c:450 local_bh_enable include/linux/bottom_half.h:33 [inline] __alloc_skb+0x6b1/0x6f0 net/core/skbuff.c:699 alloc_skb include/linux/skbuff.h:1384 [inline] nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:819 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:876 [inline] nsim_dev_trap_report_work+0x18b/0x630 drivers/net/netdevsim/dev.c:922 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405 worker_thread+0x569/0x750 kernel/workqueue.c:3486 kthread+0x221/0x270 kernel/kthread.c:436 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 read-write to 0xffff8881000c5cd8 of 8 bytes by interrupt on cpu 0: wq_worker_tick+0x64/0x240 kernel/workqueue.c:1508 sched_tick+0xbc/0x1f0 kernel/sched/core.c:5804 update_process_times+0x15e/0x190 kernel/time/timer.c:2480 tick_sched_handle kernel/time/tick-sched.c:296 [inline] tick_nohz_handler+0x227/0x380 kernel/time/tick-sched.c:317 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x257/0x810 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 decode_watchpoint kernel/kcsan/encoding.h:74 [inline] find_watchpoint kernel/kcsan/core.c:132 [inline] check_access kernel/kcsan/core.c:737 [inline] __tsan_read1+0x2d/0x180 kernel/kcsan/core.c:1022 nf_nat_ipv6_out+0x153/0x240 net/netfilter/nf_nat_proto.c:976 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0x78/0x180 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK_COND include/linux/netfilter.h:306 [inline] ip6_output+0x23c/0x280 net/ipv6/ip6_output.c:246 dst_output include/net/dst.h:471 [inline] ip6_local_out+0x77/0xd0 net/ipv6/output_core.c:128 synproxy_send_tcp_ipv6+0x35b/0x3a0 net/netfilter/nf_synproxy_core.c:861 synproxy_send_client_synack_ipv6+0x51a/0x570 net/netfilter/nf_synproxy_core.c:907 nft_synproxy_eval_v6+0x21f/0x270 net/netfilter/nft_synproxy.c:90 nft_synproxy_do_eval+0x203/0x270 net/netfilter/nft_synproxy.c:145 nft_synproxy_eval+0x29/0x40 net/netfilter/nft_synproxy.c:247 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] nft_do_chain+0x1ff/0xde0 net/netfilter/nf_tables_core.c:285 nft_do_chain_inet+0x2f0/0x320 net/netfilter/nft_chain_filter.c:162 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline] nf_hook_slow+0x78/0x180 net/netfilter/core.c:619 nf_hook include/linux/netfilter.h:273 [inline] NF_HOOK include/linux/netfilter.h:316 [inline] ip6_input+0x118/0x160 net/ipv6/ip6_input.c:545 dst_input include/net/dst.h:481 [inline] ip6_rcv_finish+0x1f5/0x330 net/ipv6/ip6_input.c:119 NF_HOOK include/linux/netfilter.h:318 [inline] ipv6_rcv+0x72/0x170 net/ipv6/ip6_input.c:351 __netif_receive_skb_one_core net/core/dev.c:6212 [inline] __netif_receive_skb net/core/dev.c:6325 [inline] process_backlog+0x2a2/0x680 net/core/dev.c:6676 __napi_poll+0x61/0x300 net/core/dev.c:7735 napi_poll net/core/dev.c:7798 [inline] net_rx_action+0x456/0x930 net/core/dev.c:7955 handle_softirqs+0xb9/0x280 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0x42/0xd0 kernel/softirq.c:735 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 constant_test_bit arch/x86/include/asm/bitops.h:202 [inline] arch_test_bit arch/x86/include/asm/bitops.h:232 [inline] _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline] netif_running include/linux/netdevice.h:4055 [inline] nsim_dev_trap_report_work+0xb3/0x630 drivers/net/netdevsim/dev.c:919 process_one_work kernel/workqueue.c:3322 [inline] process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405 worker_thread+0x569/0x750 kernel/workqueue.c:3486 kthread+0x221/0x270 kernel/kthread.c:436 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 value changed: 0x00000000022b1d60 -> 0x00000000022b4470 Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 23895 Comm: kworker/u8:75 Tainted: G W syzkaller #0 PREEMPT(lazy) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Workqueue: events_unbound nsim_dev_trap_report_work ==================================================================