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BUG: KCSAN: data-race in __xa_clear_mark / xas_find_marked

read-write to 0xffff888100413900 of 8 bytes by interrupt 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_clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:114 [inline]
 node_clear_mark lib/xarray.c:102 [inline]
 xas_clear_mark lib/xarray.c:922 [inline]
 __xa_clear_mark+0xf5/0x1e0 lib/xarray.c:2094
 __folio_end_writeback+0x177/0x470 mm/page-writeback.c:3047
 folio_end_writeback+0xb6/0x3a0 mm/filemap.c:1648
 end_buffer_async_write+0x156/0x1f0 fs/buffer.c:420
 end_bio_bh_io_sync+0x76/0xa0 fs/buffer.c:2783
 bio_endio+0x34f/0x3f0 block/bio.c:1551
 blk_update_request+0x339/0x730 block/blk-mq.c:983
 blk_mq_end_request+0x26/0x50 block/blk-mq.c:1145
 lo_complete_rq+0x98/0x140 drivers/block/loop.c:304
 blk_complete_reqs block/blk-mq.c:1220 [inline]
 blk_done_softirq+0x74/0xb0 block/blk-mq.c:1225
 handle_softirqs+0xb7/0x290 kernel/softirq.c:579
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:968
 smpboot_thread_fn+0x328/0x530 kernel/smpboot.c:164
 kthread+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888100413900 of 8 bytes by task 3301 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1746 [inline]
 xas_find_marked+0x218/0x620 lib/xarray.c:1510
 find_get_entry+0x5d/0x380 mm/filemap.c:2027
 filemap_get_folios_tag+0x13b/0x210 mm/filemap.c:2295
 __filemap_fdatawait_range mm/filemap.c:530 [inline]
 filemap_write_and_wait_range+0x1d3/0x340 mm/filemap.c:700
 filemap_write_and_wait include/linux/pagemap.h:68 [inline]
 sync_blockdev+0x35/0x50 block/bdev.c:260
 ext4_put_super+0x610/0x7d0 fs/ext4/super.c:1342
 generic_shutdown_super+0xe3/0x210 fs/super.c:642
 kill_block_super+0x2a/0x70 fs/super.c:1710
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7393
 deactivate_locked_super+0x72/0x1c0 fs/super.c:473
 deactivate_super+0x97/0xa0 fs/super.c:506
 cleanup_mnt+0x269/0x2e0 fs/namespace.c:1435
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1442
 task_work_run+0x12e/0x1a0 kernel/task_work.c:227
 resume_user_mode_work+0x6a/0x70 include/linux/resume_user_mode.h:50
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x77/0xb0 kernel/entry/common.c:218
 do_syscall_64+0xdd/0x1a0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000003 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3301 Comm: syz-executor Not tainted 6.15.0-rc4-syzkaller-00021-gca91b9500108 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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