syzbot

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BUG: KCSAN: data-race in __filemap_fdatawrite_range / xas_clear_mark

write to 0xffff888128d5eb94 of 4 bytes by task 31343 on cpu 1:
 xa_mark_clear lib/xarray.c:75 [inline]
 xas_clear_mark lib/xarray.c:918 [inline]
 xas_clear_mark+0x160/0x170 lib/xarray.c:899
 __xa_clear_mark+0xdd/0x110 lib/xarray.c:1724
 test_clear_page_writeback+0x46e/0x7e0 mm/page-writeback.c:2731
 end_page_writeback+0x98/0x180 mm/filemap.c:1317
 ext4_finish_bio+0x430/0x540 fs/ext4/page-io.c:148
 ext4_release_io_end+0xc5/0x270 fs/ext4/page-io.c:163
 ext4_end_io_end fs/ext4/page-io.c:197 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:262 [inline]
 ext4_end_io_rsv_work+0x159/0x400 fs/ext4/page-io.c:276
 process_one_work+0x424/0x930 kernel/workqueue.c:2264
 worker_thread+0x9a/0x7e0 kernel/workqueue.c:2410
 kthread+0x1cb/0x1f0 kernel/kthread.c:255
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff888128d5eb94 of 4 bytes by task 4236 on cpu 0:
 mapping_tagged include/linux/fs.h:521 [inline]
 __filemap_fdatawrite_range+0x123/0x220 mm/filemap.c:417
 filemap_write_and_wait_range mm/filemap.c:654 [inline]
 filemap_write_and_wait_range+0xad/0x140 mm/filemap.c:648
 iomap_dio_rw+0x3a2/0x9a0 fs/iomap/direct-io.c:471
 ext4_dio_read_iter fs/ext4/file.c:77 [inline]
 ext4_file_read_iter fs/ext4/file.c:129 [inline]
 ext4_file_read_iter+0x2b4/0x360 fs/ext4/file.c:114
 call_read_iter include/linux/fs.h:1895 [inline]
 generic_file_splice_read+0x2df/0x470 fs/splice.c:313
 do_splice_to+0xc7/0x100 fs/splice.c:892
 splice_direct_to_actor+0x1b9/0x540 fs/splice.c:971
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x396/0x810 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x121/0x140 fs/read_write.c:1567
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4236 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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