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BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

read-write to 0xffff8881069876b0 of 8 bytes by task 53 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+0x90/0x180 lib/xarray.c:915
 __folio_start_writeback+0x2e2/0x440 mm/page-writeback.c:3152
 __block_write_full_folio+0x506/0x8c0 fs/buffer.c:1904
 block_write_full_folio+0x293/0x2b0
 write_cache_pages+0x62/0x100 mm/page-writeback.c:2640
 blkdev_writepages+0x59/0x90 block/fops.c:437
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2683
 __writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1658
 writeback_sb_inodes+0x461/0xa30 fs/fs-writeback.c:1954
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:2025
 wb_writeback+0x274/0x640 fs/fs-writeback.c:2136
 wb_check_background_flush fs/fs-writeback.c:2206 [inline]
 wb_do_writeback fs/fs-writeback.c:2294 [inline]
 wb_workfn+0x67f/0x940 fs/fs-writeback.c:2321
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff8881069876b0 of 8 bytes by task 12031 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1733 [inline]
 xas_find_marked+0x216/0x660 lib/xarray.c:1370
 find_get_entry+0x54/0x390 mm/filemap.c:1994
 filemap_get_folios_tag+0x136/0x210 mm/filemap.c:2261
 writeback_get_folio mm/page-writeback.c:2489 [inline]
 writeback_iter+0x4b0/0x830 mm/page-writeback.c:2590
 write_cache_pages+0x4b/0x100 mm/page-writeback.c:2639
 blkdev_writepages+0x59/0x90 block/fops.c:437
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2683
 filemap_fdatawrite_wbc+0xdb/0x100 mm/filemap.c:398
 __filemap_fdatawrite_range mm/filemap.c:431 [inline]
 __filemap_fdatawrite mm/filemap.c:437 [inline]
 filemap_flush+0x61/0x90 mm/filemap.c:464
 sync_blockdev_nowait+0x29/0x40 block/bdev.c:207
 sync_filesystem+0xe3/0x190 fs/sync.c:60
 generic_shutdown_super+0x46/0x220 fs/super.c:621
 kill_block_super+0x2a/0x70 fs/super.c:1696
 ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7320
 deactivate_locked_super+0x7d/0x1c0 fs/super.c:473
 deactivate_super+0x9f/0xb0 fs/super.c:506
 cleanup_mnt+0x268/0x2e0 fs/namespace.c:1373
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1380
 task_work_run+0x13a/0x1a0 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x5dd/0x17f0 kernel/exit.c:939
 do_group_exit+0x142/0x150 kernel/exit.c:1088
 __do_sys_exit_group kernel/exit.c:1099 [inline]
 __se_sys_exit_group kernel/exit.c:1097 [inline]
 __x64_sys_exit_group+0x1f/0x20 kernel/exit.c:1097
 x64_sys_call+0x2d5d/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000000000000000a -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 12031 Comm: syz-executor Not tainted 6.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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EXT4-fs (loop0): unmounting filesystem 00000000-0000-0000-0000-000000000000.