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BUG: KCSAN: data-race in __xa_clear_mark / xas_find_marked

read-write to 0xffff88810796afe0 of 8 bytes by interrupt on cpu 1:
 instrument_read_write include/linux/instrumented.h:56 [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:2100
 __folio_end_writeback+0xf4/0x360 mm/page-writeback.c:2969
 folio_end_writeback_no_dropbehind+0x6d/0x1d0 mm/filemap.c:1667
 folio_end_writeback+0x1c/0x70 mm/filemap.c:1693
 ext4_finish_bio+0x450/0x760 fs/ext4/page-io.c:144
 ext4_end_bio+0x27b/0x380 fs/ext4/page-io.c:392
 bio_endio+0x35b/0x3f0 block/bio.c:1794
 blk_update_request+0x338/0x710 block/blk-mq.c:1016
 scsi_end_request+0x53/0x4c0 drivers/scsi/scsi_lib.c:647
 scsi_io_completion+0x7f/0x1d0 drivers/scsi/scsi_lib.c:1088
 scsi_finish_command+0x1c7/0x1e0 drivers/scsi/scsi.c:198
 scsi_complete+0x155/0x4f0 drivers/scsi/scsi_lib.c:1568
 blk_complete_reqs block/blk-mq.c:1253 [inline]
 blk_done_softirq+0x77/0xb0 block/blk-mq.c:1258
 handle_softirqs+0xb9/0x280 kernel/softirq.c:622
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:1076
 smpboot_thread_fn+0x32a/0x510 kernel/smpboot.c:160
 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 0xffff88810796afe0 of 8 bytes by task 10098 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1752 [inline]
 xas_find_marked+0x213/0x620 lib/xarray.c:1510
 find_get_entry mm/filemap.c:2070 [inline]
 filemap_get_folios_tag+0xfa/0x430 mm/filemap.c:2338
 __filemap_fdatawait_range mm/filemap.c:524 [inline]
 filemap_fdatawait_keep_errors+0x6c/0x190 mm/filemap.c:627
 wait_sb_inodes fs/fs-writeback.c:2812 [inline]
 sync_inodes_sb+0x424/0x4d0 fs/fs-writeback.c:2945
 sync_inodes_one_sb+0x3d/0x50 fs/sync.c:77
 __iterate_supers+0x110/0x1f0 fs/super.c:927
 iterate_supers+0x1f/0x30 fs/super.c:942
 ksys_sync fs/sync.c:102 [inline]
 __ia32_sys_sync+0x5c/0xb0 fs/sync.c:111
 x64_sys_call+0x2f3a/0x3020 arch/x86/include/generated/asm/syscalls_64.h:163
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xd3b0e5947cbff080 -> 0xd3b0e59440bff080

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 10098 Comm: syz.8.1587 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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