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BUG: KCSAN: data-race in __filemap_fdatawrite_range / xas_clear_mark

write to 0xffff888125281ad4 of 4 bytes by interrupt on cpu 1:
 xa_mark_clear lib/xarray.c:75 [inline]
 xas_clear_mark lib/xarray.c:918 [inline]
 xas_clear_mark+0x171/0x180 lib/xarray.c:899
 __xa_clear_mark+0xd3/0x100 lib/xarray.c:1724
 test_clear_page_writeback+0x44c/0x790 mm/page-writeback.c:2731
 end_page_writeback+0x9e/0x190 mm/filemap.c:1317
 end_buffer_async_write+0x2dc/0x3a0 fs/buffer.c:389
 end_bio_bh_io_sync+0x87/0xb0 fs/buffer.c:3018
 bio_endio+0x2fa/0x400 block/bio.c:1872
 req_bio_endio block/blk-core.c:245 [inline]
 blk_update_request+0x427/0x7b0 block/blk-core.c:1468
 blk_mq_end_request+0x52/0x300 block/blk-mq.c:546
 lo_complete_rq+0x136/0x1a0 drivers/block/loop.c:487
 blk_done_softirq+0x1eb/0x250 block/blk-softirq.c:37
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 run_ksoftirqd+0x46/0x60 kernel/softirq.c:603
 smpboot_thread_fn+0x37d/0x4a0 kernel/smpboot.c:165
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff888125281ad4 of 4 bytes by task 7998 on cpu 0:
 mapping_tagged include/linux/fs.h:521 [inline]
 __filemap_fdatawrite_range+0x125/0x230 mm/filemap.c:417
 filemap_write_and_wait_range mm/filemap.c:654 [inline]
 filemap_write_and_wait_range+0xb1/0x150 mm/filemap.c:648
 filemap_write_and_wait include/linux/fs.h:2762 [inline]
 __sync_blockdev+0x69/0xa0 fs/block_dev.c:491
 __sync_filesystem fs/sync.c:40 [inline]
 sync_filesystem fs/sync.c:67 [inline]
 sync_filesystem+0x186/0x1a0 fs/sync.c:48
 generic_shutdown_super+0x6b/0x270 fs/super.c:448
 kill_block_super+0x60/0xb0 fs/super.c:1444
 deactivate_locked_super+0x64/0xb0 fs/super.c:335
 deactivate_super fs/super.c:366 [inline]
 deactivate_super+0xca/0xe0 fs/super.c:362
 cleanup_mnt+0x291/0x340 fs/namespace.c:1102
 __cleanup_mnt+0x1f/0x30 fs/namespace.c:1109
 task_work_run+0xf6/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2b4/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x384/0x3a0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7998 Comm: syz-executor.0 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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