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BUG: KCSAN: data-race in __xa_clear_mark / xas_find_marked

read-write to 0xffff888100602fe0 of 8 bytes by interrupt 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 lib/xarray.c:922 [inline]
 __xa_clear_mark+0xf5/0x1e0 lib/xarray.c:2100
 __folio_end_writeback+0xf7/0x3b0 mm/page-writeback.c:2998
 folio_end_writeback_no_dropbehind+0x6d/0x1b0 mm/filemap.c:1668
 folio_end_writeback+0x1c/0x70 mm/filemap.c:1694
 ext4_finish_bio+0x459/0x8c0 fs/ext4/page-io.c:144
 ext4_end_bio+0x298/0x3b0 fs/ext4/page-io.c:-1
 bio_endio+0x37b/0x420 block/bio.c:1673
 blk_update_request+0x336/0x730 block/blk-mq.c:998
 blk_mq_end_request+0x26/0x50 block/blk-mq.c:1160
 lo_complete_rq+0x98/0x140 drivers/block/loop.c:314
 blk_complete_reqs block/blk-mq.c:1235 [inline]
 blk_done_softirq+0x77/0xb0 block/blk-mq.c:1240
 handle_softirqs+0xb7/0x290 kernel/softirq.c:622
 run_ksoftirqd+0x1c/0x30 kernel/softirq.c:1063
 smpboot_thread_fn+0x32b/0x530 kernel/smpboot.c:160
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888100602fe0 of 8 bytes by task 10157 on cpu 1:
 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:2070
 filemap_get_folios_tag+0x13b/0x210 mm/filemap.c:2338
 __filemap_fdatawait_range mm/filemap.c:533 [inline]
 file_write_and_wait_range+0x1ea/0x2c0 mm/filemap.c:801
 generic_buffers_fsync_noflush+0x45/0x120 fs/buffer.c:609
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x1ab/0x690 fs/ext4/fsync.c:147
 vfs_fsync_range+0x10d/0x130 fs/sync.c:187
 generic_write_sync include/linux/fs.h:3046 [inline]
 ext4_buffered_write_iter+0x34f/0x3c0 fs/ext4/file.c:305
 ext4_dio_write_iter fs/ext4/file.c:613 [inline]
 ext4_file_write_iter+0xe27/0xf60 fs/ext4/file.c:721
 iter_file_splice_write+0x663/0xa60 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x153/0x2a0 fs/splice.c:1161
 splice_direct_to_actor+0x30f/0x680 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1230
 do_sendfile+0x380/0x650 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
 x64_sys_call+0x2bb4/0x3000 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x000000000000ffff -> 0x000000000000fff8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 10157 Comm: syz.3.2875 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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