EXT4-fs (loop0): unmounting filesystem 00000000-0000-0000-0000-000000000000.
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BUG: KCSAN: data-race in kick_pool / wq_worker_running

read-write to 0xffff888237c2a8e4 of 4 bytes by task 3573 on cpu 0:
 wq_worker_running+0x9b/0x120 kernel/workqueue.c:1434
 schedule_timeout+0xca/0x180 kernel/time/sleep_timeout.c:99
 schedule_timeout_uninterruptible kernel/time/sleep_timeout.c:158 [inline]
 msleep+0x4f/0x90 kernel/time/sleep_timeout.c:318
 nsim_fib4_rt_add drivers/net/netdevsim/fib.c:369 [inline]
 nsim_fib4_rt_insert drivers/net/netdevsim/fib.c:432 [inline]
 nsim_fib4_event drivers/net/netdevsim/fib.c:464 [inline]
 nsim_fib_event+0x3e17/0x4d40 drivers/net/netdevsim/fib.c:884
 nsim_fib_event_work+0x13d/0x210 drivers/net/netdevsim/fib.c:1493
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3397
 worker_thread+0x58a/0x780 kernel/workqueue.c:3478
 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 to 0xffff888237c2a8e4 of 4 bytes by task 3297 on cpu 1:
 need_more_worker kernel/workqueue.c:952 [inline]
 kick_pool+0x49/0x2d0 kernel/workqueue.c:1274
 __queue_work+0x8b9/0xb00 kernel/workqueue.c:2394
 queue_work_on+0xa9/0x140 kernel/workqueue.c:2444
 __lru_add_drain_all+0x319/0x450 mm/swap.c:885
 lru_add_drain_all+0x10/0x20 mm/swap.c:899
 invalidate_bdev+0x47/0x70 block/bdev.c:101
 ext4_put_super+0x610/0x7b0 fs/ext4/super.c:1355
 generic_shutdown_super+0xee/0x220 fs/super.c:646
 kill_block_super+0x2a/0x70 fs/super.c:1725
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7492
 deactivate_locked_super+0x75/0x1c0 fs/super.c:476
 deactivate_super+0x97/0xa0 fs/super.c:509
 cleanup_mnt+0x2bb/0x330 fs/namespace.c:1312
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1319
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x211/0x820 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x232/0x3b0 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: 1 UID: 0 PID: 3297 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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