================================================================== 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:5677 update_process_times+0x15e/0x190 kernel/time/timer.c:2480 tick_sched_handle kernel/time/tick-sched.c:298 [inline] tick_nohz_handler+0x275/0x3d0 kernel/time/tick-sched.c:319 __run_hrtimer kernel/time/hrtimer.c:1930 [inline] __hrtimer_run_queues+0x276/0x4f0 kernel/time/hrtimer.c:1994 hrtimer_interrupt+0x261/0x850 kernel/time/hrtimer.c:2113 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1067 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline] sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1061 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 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 skb_ext_get_ptr net/core/skbuff.c:7031 [inline] skb_ext_add+0x23c/0x390 net/core/skbuff.c:7161 vxcan_xmit+0xee/0x360 drivers/net/can/vxcan.c:73 __netdev_start_xmit include/linux/netdevice.h:5343 [inline] netdev_start_xmit include/linux/netdevice.h:5352 [inline] xmit_one net/core/dev.c:3888 [inline] dev_hard_start_xmit+0x12a/0x3a0 net/core/dev.c:3904 __dev_queue_xmit+0xbd5/0x1ec0 net/core/dev.c:4870 dev_queue_xmit include/linux/netdevice.h:3401 [inline] can_send+0x589/0x720 net/can/af_can.c:279 can_can_gw_rcv+0x817/0x870 net/can/gw.c:569 deliver net/can/af_can.c:575 [inline] can_rcv_filter+0xc3/0x480 net/can/af_can.c:602 can_receive+0x13e/0x190 net/can/af_can.c:674 can_rcv+0x17d/0x1f0 net/can/af_can.c:699 __netif_receive_skb_one_core net/core/dev.c:6209 [inline] __netif_receive_skb net/core/dev.c:6322 [inline] process_backlog+0x363/0x670 net/core/dev.c:6673 __napi_poll+0x61/0x300 net/core/dev.c:7737 napi_poll net/core/dev.c:7800 [inline] net_rx_action+0x452/0x930 net/core/dev.c:7957 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 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:196 [inline] _raw_spin_unlock_bh+0x18/0x20 kernel/locking/spinlock.c:214 spin_unlock_bh include/linux/spinlock.h:396 [inline] nsim_dev_trap_report drivers/net/netdevsim/dev.c:891 [inline] nsim_dev_trap_report_work+0x52b/0x630 drivers/net/netdevsim/dev.c:922 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3385 worker_thread+0x58a/0x780 kernel/workqueue.c:3466 kthread+0x22a/0x280 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:5677 update_process_times+0x15e/0x190 kernel/time/timer.c:2480 tick_sched_handle kernel/time/tick-sched.c:298 [inline] tick_nohz_handler+0x275/0x3d0 kernel/time/tick-sched.c:319 __run_hrtimer kernel/time/hrtimer.c:1930 [inline] __hrtimer_run_queues+0x276/0x4f0 kernel/time/hrtimer.c:1994 hrtimer_interrupt+0x261/0x850 kernel/time/hrtimer.c:2113 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1067 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline] sysvec_apic_timer_interrupt+0x32/0x80 arch/x86/kernel/apic/apic.c:1061 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 __tsan_read4+0x12/0x190 kernel/kcsan/core.c:1024 skb_is_nonlinear include/linux/skbuff.h:2528 [inline] skb_put net/core/skbuff.c:2624 [inline] skb_copy+0x17e/0x3f0 net/core/skbuff.c:2190 can_can_gw_rcv+0x29d/0x870 net/can/gw.c:507 deliver net/can/af_can.c:575 [inline] can_rcv_filter+0xc3/0x480 net/can/af_can.c:602 can_receive+0x13e/0x190 net/can/af_can.c:674 can_rcv+0x17d/0x1f0 net/can/af_can.c:699 __netif_receive_skb_one_core net/core/dev.c:6209 [inline] __netif_receive_skb net/core/dev.c:6322 [inline] process_backlog+0x363/0x670 net/core/dev.c:6673 __napi_poll+0x61/0x300 net/core/dev.c:7737 napi_poll net/core/dev.c:7800 [inline] net_rx_action+0x452/0x930 net/core/dev.c:7957 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+0x658/0x690 net/core/skbuff.c:697 alloc_skb include/linux/skbuff.h:1383 [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+0x18a/0x630 drivers/net/netdevsim/dev.c:922 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3385 worker_thread+0x58a/0x780 kernel/workqueue.c:3466 kthread+0x22a/0x280 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: 0x0000000007d1a5e0 -> 0x0000000007d1ccf0 Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 16423 Comm: kworker/u8:3 Tainted: G W syzkaller #0 PREEMPT(full) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Workqueue: events_unbound nsim_dev_trap_report_work ==================================================================