==================================================================
BUG: KCSAN: data-race in kick_pool / wq_worker_running

read-write to 0xffff888237d29da4 of 4 bytes by task 3395 on cpu 1:
 wq_worker_running+0x95/0x120 kernel/workqueue.c:1406
 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:7083
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x467/0xcc0 kernel/locking/mutex.c:760
 __mutex_lock_slowpath+0xa/0x10 kernel/locking/mutex.c:1049
 mutex_lock+0x27/0x30 kernel/locking/mutex.c:274
 exp_funnel_lock kernel/rcu/tree_exp.h:343 [inline]
 synchronize_rcu_expedited+0x18a/0x790 kernel/rcu/tree_exp.h:957
 synchronize_rcu+0x45/0x320 kernel/rcu/tree.c:3352
 free_ipc+0x80/0x1c0 ipc/namespace.c:178
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3346
 worker_thread+0x582/0x770 kernel/workqueue.c:3427
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888237d29da4 of 4 bytes by task 26145 on cpu 0:
 need_more_worker kernel/workqueue.c:940 [inline]
 kick_pool+0x49/0x2d0 kernel/workqueue.c:1246
 __queue_work+0x8cb/0xb50 kernel/workqueue.c:2342
 queue_work_on+0xd1/0x160 kernel/workqueue.c:2392
 queue_work include/linux/workqueue.h:669 [inline]
 schedule_work include/linux/workqueue.h:730 [inline]
 put_ipc_ns+0x130/0x1d0 ipc/namespace.c:208
 free_nsproxy+0x88/0x2a0 kernel/nsproxy.c:190
 put_nsproxy include/linux/nsproxy.h:107 [inline]
 switch_task_namespaces kernel/nsproxy.c:241 [inline]
 exit_task_namespaces+0x78/0xc0 kernel/nsproxy.c:246
 do_exit+0x47e/0x15c0 kernel/exit.c:960
 do_group_exit+0xff/0x140 kernel/exit.c:1102
 get_signal+0xe58/0xf70 kernel/signal.c:3034
 arch_do_signal_or_restart+0x96/0x440 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x77/0xf0 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 26145 Comm: syz.0.8347 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
==================================================================