syzbot

ID	Workflow	Result	Correct	Bug	Created	Started	Finished	Revision	Error
900af779-651d-4649-825d-fdd54228c6cf	assessment-kcsan		💥	KCSAN: data-race in wq_worker_tick / wq_worker_tick	2026/01/09 14:24	2026/01/09 14:24	2026/01/09 14:26	9ee25c60da3366005e31dedd1574732f63338151	failed to load compile commands: open /usr/local/google/home/dvyukov/syzkaller/agent/workdir/cache/build/9dce9dd65e825296b412dc760805ab08dc7d0dbc/compile_commands.json: no such file or directory

==================================================================
BUG: KCSAN: data-race in wq_worker_tick / wq_worker_tick

read-write to 0xffff888100a13ab8 of 8 bytes by interrupt on cpu 0:
 wq_worker_tick+0x60/0x230 kernel/workqueue.c:1474
 sched_tick+0xd7/0x220 kernel/sched/core.c:5546
 update_process_times+0x15f/0x190 kernel/time/timer.c:2479
 tick_sched_handle kernel/time/tick-sched.c:298 [inline]
 tick_nohz_handler+0x276/0x3d0 kernel/time/tick-sched.c:319
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x20f/0x5a0 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x21a/0x460 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1d0 arch/x86/kernel/apic/apic.c:1062
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 __preempt_count_dec_and_test arch/x86/include/asm/preempt.h:95 [inline]
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
 _raw_spin_unlock_irq+0x2f/0x50 kernel/locking/spinlock.c:202
 process_one_work kernel/workqueue.c:3226 [inline]
 process_scheduled_works+0x486/0x9d0 kernel/workqueue.c:3340
 worker_thread+0x582/0x770 kernel/workqueue.c:3421
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

read-write to 0xffff888100a13ab8 of 8 bytes by interrupt on cpu 1:
 wq_worker_tick+0x60/0x230 kernel/workqueue.c:1474
 sched_tick+0xd7/0x220 kernel/sched/core.c:5546
 update_process_times+0x15f/0x190 kernel/time/timer.c:2479
 tick_sched_handle kernel/time/tick-sched.c:298 [inline]
 tick_nohz_handler+0x276/0x3d0 kernel/time/tick-sched.c:319
 __run_hrtimer kernel/time/hrtimer.c:1777 [inline]
 __hrtimer_run_queues+0x20f/0x5a0 kernel/time/hrtimer.c:1841
 hrtimer_interrupt+0x21a/0x460 kernel/time/hrtimer.c:1903
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1d0 arch/x86/kernel/apic/apic.c:1062
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 __preempt_count_dec_and_test arch/x86/include/asm/preempt.h:95 [inline]
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline]
 _raw_spin_unlock_irq+0x2f/0x50 kernel/locking/spinlock.c:202
 process_one_work kernel/workqueue.c:3226 [inline]
 process_scheduled_works+0x486/0x9d0 kernel/workqueue.c:3340
 worker_thread+0x582/0x770 kernel/workqueue.c:3421
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x00000000001842f0 -> 0x0000000000186a00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5741 Comm: kworker/u8:49 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: iou_exit io_ring_exit_work
==================================================================

Seq	Timestamp	Type	Name	Duration
0/0	2026/01/09 14:24	flow	assessment-kcsan	2m Model: unknown Error: failed to load compile commands: open /usr/local/google/home/dvyukov/syzkaller/agent/workdir/cache/build/9dce9dd65e825296b412dc760805ab08dc7d0dbc/compile_commands.json: no such file or directory
1/1	2026/01/09 14:24	action	kernel-checkouter	0m Model: unknown Results: map[KernelSrc:/usr/local/google/home/dvyukov/syzkaller/agent/workdir/cache/src/761c89d80a8577d5dba2a721de12cc04cb43ff14]
2/1	2026/01/09 14:24	action	kernel-builder	1m Model: unknown Results: map[KernelObj:/usr/local/google/home/dvyukov/syzkaller/agent/workdir/cache/build/9dce9dd65e825296b412dc760805ab08dc7d0dbc]
3/1	2026/01/09 14:26	action	codesearch-prepare	0m Model: unknown Error: failed to load compile commands: open /usr/local/google/home/dvyukov/syzkaller/agent/workdir/cache/build/9dce9dd65e825296b412dc760805ab08dc7d0dbc/compile_commands.json: no such file or directory Results: map[Index:codesearch-index]