syzbot

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BUG: KCSAN: data-race in __xa_set_mark / xas_find_marked

read-write to 0xffff8881079ce900 of 8 bytes by task 42 on cpu 1:
 instrument_read_write include/linux/instrumented.h:55 [inline]
 __instrument_read_write_bitop include/asm-generic/bitops/instrumented-non-atomic.h:84 [inline]
 ___test_and_set_bit include/asm-generic/bitops/instrumented-non-atomic.h:99 [inline]
 node_set_mark lib/xarray.c:95 [inline]
 xas_set_mark lib/xarray.c:893 [inline]
 __xa_set_mark+0xd2/0x1a0 lib/xarray.c:2082
 ref_tracker_debugfs_mark lib/ref_tracker.c:56 [inline]
 ref_tracker_dir_exit+0x5e/0x360 lib/ref_tracker.c:231
 free_netdev+0x2fa/0x460 net/core/dev.c:12164
 netdev_run_todo+0x7b8/0x8c0 net/core/dev.c:11695
 rtnl_unlock+0xe/0x20 net/core/rtnetlink.c:157
 ops_exit_rtnl_list net/core/net_namespace.c:189 [inline]
 ops_undo_list+0x218/0x410 net/core/net_namespace.c:248
 cleanup_net+0x2f4/0x520 net/core/net_namespace.c:696
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0x4ce/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 to 0xffff8881079ce900 of 8 bytes by task 3427 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1752 [inline]
 xas_find_marked+0x218/0x620 lib/xarray.c:1510
 xa_find_after+0xc6/0x1e0 lib/xarray.c:2251
 debugfs_reap_work+0x18c/0x1d0 lib/ref_tracker.c:511
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0x4ce/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: 0x000000040c000800 -> 0x000000050c000810

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3427 Comm: kworker/0:4 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: events debugfs_reap_work
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