syzbot

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BUG: KCSAN: data-race in kick_pool / wq_worker_running

read-write to 0xffff888237c29de4 of 4 bytes by task 9 on cpu 0:
 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
 pcpu_balance_workfn+0x4a/0xc00 mm/percpu.c:2204
 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+0x486/0x510 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 0xffff888237c29de4 of 4 bytes by task 18149 on cpu 1:
 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]
 pcpu_schedule_balance_work mm/percpu.c:204 [inline]
 pcpu_alloc_noprof+0x9a7/0x1250 mm/percpu.c:1856
 bpf_prog_alloc_no_stats+0xf7/0x3b0 kernel/bpf/core.c:115
 bpf_prog_alloc+0x3c/0x150 kernel/bpf/core.c:153
 bpf_prog_load+0x506/0x1100 kernel/bpf/syscall.c:2966
 __sys_bpf+0x469/0x7c0 kernel/bpf/syscall.c:6134
 __do_sys_bpf kernel/bpf/syscall.c:6244 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:6242 [inline]
 __x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6242
 x64_sys_call+0x2aee/0x3000 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 18149 Comm: syz.0.6130 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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