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BUG: KCSAN: data-race in __xa_clear_mark / xas_find_marked

write to 0xffff88810dfb7d70 of 8 bytes by interrupt on cpu 0:
 instrument_write include/linux/instrumented.h:42 [inline]
 __instrument_read_write_bitop include/asm-generic/bitops/instrumented-non-atomic.h:79 [inline]
 __test_and_clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:109 [inline]
 node_clear_mark lib/xarray.c:100 [inline]
 xas_clear_mark lib/xarray.c:911 [inline]
 __xa_clear_mark+0xff/0x1e0 lib/xarray.c:1916
 test_clear_page_writeback+0x321/0x520 mm/page-writeback.c:2739
 end_page_writeback+0xd7/0x260 mm/filemap.c:1494
 page_endio+0x1be/0x200 mm/filemap.c:1526
 mpage_end_io+0x186/0x1d0 fs/mpage.c:54
 bio_endio+0x285/0x350 block/bio.c:1450
 req_bio_endio block/blk-core.c:264 [inline]
 blk_update_request+0x4e5/0xb00 block/blk-core.c:1462
 blk_mq_end_request+0x22/0x50 block/blk-mq.c:564
 lo_complete_rq+0xca/0x180 drivers/block/loop.c:497
 blk_done_softirq+0x145/0x190 block/blk-mq.c:588
 __do_softirq+0x13c/0x2c3 kernel/softirq.c:343
 run_ksoftirqd+0x13/0x20 kernel/softirq.c:650
 smpboot_thread_fn+0x34f/0x520 kernel/smpboot.c:165
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff88810dfb7d70 of 8 bytes by task 12227 on cpu 1:
 xas_find_chunk include/linux/xarray.h:1660 [inline]
 xas_find_marked+0x22f/0x6b0 lib/xarray.c:1348
 find_get_pages_range_tag+0xa3/0x600 mm/filemap.c:2103
 pagevec_lookup_range_tag+0x37/0x50 mm/swap.c:1122
 __filemap_fdatawait_range+0xab/0x1b0 mm/filemap.c:519
 filemap_fdatawait_range mm/filemap.c:554 [inline]
 filemap_write_and_wait_range+0x119/0x2a0 mm/filemap.c:664
 __generic_file_write_iter+0x259/0x330 mm/filemap.c:3523
 generic_file_write_iter+0x75/0x130 mm/filemap.c:3569
 call_write_iter include/linux/fs.h:1901 [inline]
 aio_write+0x2aa/0x390 fs/aio.c:1581
 __io_submit_one fs/aio.c:1840 [inline]
 io_submit_one+0x654/0x1230 fs/aio.c:1883
 __do_sys_io_submit fs/aio.c:1942 [inline]
 __se_sys_io_submit+0xf5/0x270 fs/aio.c:1912
 __x64_sys_io_submit+0x3f/0x50 fs/aio.c:1912
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12227 Comm: syz-executor.2 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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