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BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

write to 0xffff8881221e2d70 of 8 bytes by interrupt on cpu 1:
 __test_and_clear_bit include/asm-generic/bitops-instrumented.h:213 [inline]
 node_clear_mark lib/xarray.c:99 [inline]
 xas_clear_mark+0x11a/0x1d0 lib/xarray.c:907
 __xa_clear_mark+0xd3/0x100 lib/xarray.c:1713
 test_clear_page_writeback+0x435/0x780 mm/page-writeback.c:2727
 end_page_writeback+0x9e/0x190 mm/filemap.c:1330
 ext4_finish_bio+0x40d/0x520 fs/ext4/page-io.c:110
 ext4_end_bio+0xd2/0x310 fs/ext4/page-io.c:334
 bio_endio+0x3ab/0x500 block/bio.c:1830
 req_bio_endio block/blk-core.c:239 [inline]
 blk_update_request+0x21d/0x6a0 block/blk-core.c:1424
 scsi_end_request+0x6b/0x3e0 drivers/scsi/scsi_lib.c:579
 scsi_io_completion+0x11d/0xc80 drivers/scsi/scsi_lib.c:963
 scsi_finish_command+0x280/0x380 drivers/scsi/scsi.c:228
 scsi_softirq_done+0x259/0x280 drivers/scsi/scsi_lib.c:1465
 blk_done_softirq+0x1eb/0x250 block/blk-softirq.c:37
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xbb/0xe0 kernel/softirq.c:413

read to 0xffff8881221e2d70 of 8 bytes by task 7661 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1590 [inline]
 xas_find_marked+0x17a/0x7b0 lib/xarray.c:1187
 find_get_pages_range_tag+0x114/0x6d0 mm/filemap.c:1939
 pagevec_lookup_range_tag+0x45/0x70 mm/swap.c:1014
 __filemap_fdatawait_range+0xdc/0x1d0 mm/filemap.c:512
 file_write_and_wait_range+0xc9/0xf0 mm/filemap.c:777
 __generic_file_fsync+0x59/0x190 fs/libfs.c:996
 ext4_sync_file+0x48e/0xb00 fs/ext4/fsync.c:120
 vfs_fsync_range+0x82/0x150 fs/sync.c:197
 generic_write_sync include/linux/fs.h:2799 [inline]
 ext4_file_write_iter+0x50a/0xa40 fs/ext4/file.c:281
 call_write_iter include/linux/fs.h:1870 [inline]
 do_iter_readv_writev+0x487/0x5b0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x13b/0x3c0 fs/read_write.c:951
 vfs_iter_write+0x5c/0x80 fs/read_write.c:983
 iter_file_splice_write+0x4c0/0x7f0 fs/splice.c:746

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7661 Comm: syz-executor.1 Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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