==================================================================
BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

read-write to 0xffff888106749fd0 of 8 bytes by task 51 on cpu 0:
 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+0x2d9/0x430 mm/page-writeback.c:3164
 __block_write_full_folio+0x506/0x8c0 fs/buffer.c:1899
 block_write_full_folio+0x293/0x2b0
 write_cache_pages+0x62/0x100 mm/page-writeback.c:2665
 blkdev_writepages+0x59/0x90 block/fops.c:458
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2708
 __writeback_single_inode+0x89/0x850 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x461/0xa30 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x9a/0x1a0 fs/fs-writeback.c:2047
 wb_writeback+0x274/0x640 fs/fs-writeback.c:2158
 wb_check_background_flush fs/fs-writeback.c:2228 [inline]
 wb_do_writeback fs/fs-writeback.c:2316 [inline]
 wb_workfn+0x67f/0x940 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3317
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3398
 kthread+0x4ae/0x520 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff888106749fd0 of 8 bytes by task 7346 on cpu 1:
 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:1984
 filemap_get_folios_tag+0x9e/0x210 mm/filemap.c:2251
 writeback_get_folio mm/page-writeback.c:2514 [inline]
 writeback_iter+0x4b0/0x830 mm/page-writeback.c:2615
 write_cache_pages+0x4b/0x100 mm/page-writeback.c:2664
 blkdev_writepages+0x59/0x90 block/fops.c:458
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2708
 filemap_fdatawrite_wbc mm/filemap.c:388 [inline]
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 __filemap_fdatawrite mm/filemap.c:427 [inline]
 filemap_flush+0xe7/0x120 mm/filemap.c:454
 sync_blockdev_nowait+0x29/0x40 block/bdev.c:206
 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:1710
 ext4_kill_sb+0x44/0x80 fs/ext4/super.c:7379
 deactivate_locked_super+0x7d/0x1c0 fs/super.c:473
 deactivate_super+0x9f/0xb0 fs/super.c:506
 cleanup_mnt+0x268/0x2e0 fs/namespace.c:1413
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1420
 task_work_run+0x13a/0x1a0 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 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+0xa8/0x120 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000206 -> 0x0000000000000200

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 7346 Comm: syz-executor Not tainted 6.13.0-syzkaller-02526-gc4b9570cfb63 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
==================================================================