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BUG: KCSAN: data-race in __xa_clear_mark / xas_find_marked

read-write to 0xffff88811a8ce478 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:2100
 __folio_end_writeback+0xf4/0x360 mm/page-writeback.c:2992
 folio_end_writeback_no_dropbehind+0x6d/0x1b0 mm/filemap.c:1661
 folio_end_writeback+0x1c/0x70 mm/filemap.c:1687
 ext4_finish_bio+0x459/0x8c0 fs/ext4/page-io.c:144
 ext4_end_bio+0x27b/0x380 fs/ext4/page-io.c:392
 bio_endio+0x37e/0x420 block/bio.c:1675
 blk_update_request+0x336/0x730 block/blk-mq.c:1007
 scsi_end_request+0x53/0x4c0 drivers/scsi/scsi_lib.c:638
 scsi_io_completion+0x7f/0x1d0 drivers/scsi/scsi_lib.c:1079
 scsi_finish_command+0x1c7/0x1e0 drivers/scsi/scsi.c:198
 scsi_complete+0x155/0x4f0 drivers/scsi/scsi_lib.c:1559
 blk_complete_reqs block/blk-mq.c:1244 [inline]
 blk_done_softirq+0x77/0xb0 block/blk-mq.c:1249
 handle_softirqs+0xba/0x290 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x3a/0xc0 kernel/softirq.c:723
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 kcsan_setup_watchpoint+0x406/0x420 kernel/kcsan/core.c:705
 iov_iter_init lib/iov_iter.c:179 [inline]
 __import_iovec+0x2e9/0x540 lib/iov_iter.c:1406
 import_iovec+0x61/0x80 lib/iov_iter.c:1440
 copy_msghdr_from_user net/socket.c:2529 [inline]
 recvmsg_copy_msghdr net/socket.c:2778 [inline]
 ___sys_recvmsg+0x358/0x370 net/socket.c:2850
 do_recvmmsg+0x1ef/0x540 net/socket.c:2949
 __sys_recvmmsg net/socket.c:3023 [inline]
 __do_sys_recvmmsg net/socket.c:3046 [inline]
 __se_sys_recvmmsg net/socket.c:3039 [inline]
 __x64_sys_recvmmsg+0xe5/0x170 net/socket.c:3039
 x64_sys_call+0x2b75/0x3000 arch/x86/include/generated/asm/syscalls_64.h:300
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a8ce478 of 8 bytes by task 22057 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1752 [inline]
 xas_find_marked+0x218/0x620 lib/xarray.c:1510
 find_get_entry+0x5d/0x380 mm/filemap.c:2064
 filemap_get_folios_tag+0x13b/0x210 mm/filemap.c:2332
 __filemap_fdatawait_range mm/filemap.c:523 [inline]
 filemap_fdatawait_keep_errors+0x6c/0x180 mm/filemap.c:626
 wait_sb_inodes fs/fs-writeback.c:2775 [inline]
 sync_inodes_sb+0x3b3/0x460 fs/fs-writeback.c:2897
 sync_inodes_one_sb+0x3d/0x50 fs/sync.c:77
 __iterate_supers+0x110/0x220 fs/super.c:924
 iterate_supers+0x1f/0x30 fs/super.c:939
 ksys_sync+0x5c/0xe0 fs/sync.c:102
 __ia32_sys_sync+0xe/0x20 fs/sync.c:113
 x64_sys_call+0x29b2/0x3000 arch/x86/include/generated/asm/syscalls_64.h:163
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000001 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 22057 Comm: syz.4.3498 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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