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BUG: KCSAN: data-race in wq_worker_tick / wq_worker_tick

read-write to 0xffff88810169a6d8 of 8 bytes by interrupt on cpu 1:
 wq_worker_tick+0x64/0x240 kernel/workqueue.c:1493
 sched_tick+0xda/0x210 kernel/sched/core.c:5588
 update_process_times+0x15e/0x190 kernel/time/timer.c:2479
 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:1785 [inline]
 __hrtimer_run_queues+0x218/0x4f0 kernel/time/hrtimer.c:1849
 hrtimer_interrupt+0x269/0x810 kernel/time/hrtimer.c:1911
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1f0 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
 __tsan_unaligned_volatile_read4+0x0/0x190 kernel/kcsan/core.c:753
 __rcu_read_unlock+0x4e/0x70 kernel/rcu/tree_plugin.h:437
 rcu_read_unlock include/linux/rcupdate.h:883 [inline]
 percpu_ref_put_many include/linux/percpu-refcount.h:337 [inline]
 percpu_ref_put include/linux/percpu-refcount.h:351 [inline]
 obj_cgroup_put include/linux/memcontrol.h:794 [inline]
 __memcg_slab_free_hook+0xa0/0x240 mm/memcontrol.c:3284
 memcg_slab_free_hook mm/slub.c:2484 [inline]
 slab_free mm/slub.c:6162 [inline]
 kmem_cache_free+0x237/0x380 mm/slub.c:6295
 __io_req_caches_free+0xfe/0x210 io_uring/io_uring.c:2134
 io_req_caches_free+0x1f/0x60 io_uring/io_uring.c:2146
 io_ring_exit_work+0x1f4/0x530 io_uring/io_uring.c:2340
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0x513/0xa10 kernel/workqueue.c:3359
 worker_thread+0x58a/0x780 kernel/workqueue.c:3440
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read-write to 0xffff88810169a6d8 of 8 bytes by interrupt on cpu 0:
 wq_worker_tick+0x64/0x240 kernel/workqueue.c:1493
 sched_tick+0xda/0x210 kernel/sched/core.c:5588
 update_process_times+0x15e/0x190 kernel/time/timer.c:2479
 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:1785 [inline]
 __hrtimer_run_queues+0x218/0x4f0 kernel/time/hrtimer.c:1849
 hrtimer_interrupt+0x269/0x810 kernel/time/hrtimer.c:1911
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1045 [inline]
 __sysvec_apic_timer_interrupt+0x5f/0x1f0 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
 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_read8+0x42/0x190 kernel/kcsan/core.c:1025
 slab_pgdat mm/slab.h:167 [inline]
 __memcg_slab_free_hook+0x188/0x240 mm/memcontrol.c:3283
 memcg_slab_free_hook mm/slub.c:2484 [inline]
 slab_free mm/slub.c:6162 [inline]
 kfree+0x27e/0x380 mm/slub.c:6483
 __io_cqring_overflow_flush+0x383/0x650 io_uring/io_uring.c:553
 io_cqring_overflow_kill io_uring/io_uring.c:582 [inline]
 io_ring_exit_work+0xfa/0x530 io_uring/io_uring.c:2317
 process_one_work kernel/workqueue.c:3276 [inline]
 process_scheduled_works+0x513/0xa10 kernel/workqueue.c:3359
 worker_thread+0x58a/0x780 kernel/workqueue.c:3440
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x000000000003f7a0 -> 0x0000000000041eb0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2606 Comm: kworker/u8:12 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: iou_exit io_ring_exit_work
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