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BUG: KCSAN: data-race in find_get_pages_range_tag / xas_set_mark

read-write to 0xffff888009681238 of 8 bytes by task 30360 on cpu 1:
 instrument_read_write include/linux/instrumented.h:57 [inline]
 __instrument_read_write_bitop include/asm-generic/bitops/instrumented-non-atomic.h:81 [inline]
 __test_and_set_bit include/asm-generic/bitops/instrumented-non-atomic.h:95 [inline]
 node_set_mark lib/xarray.c:93 [inline]
 xas_set_mark+0x7f/0x130 lib/xarray.c:882
 tag_pages_for_writeback+0x9d/0x290 mm/page-writeback.c:2124
 ext4_writepages+0x62f/0x1e10 fs/ext4/inode.c:2719
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:422
 filemap_write_and_wait_range+0x8b/0x2a0 mm/filemap.c:655
 __iomap_dio_rw+0x38c/0x9b0 fs/iomap/direct-io.c:489
 iomap_dio_rw+0x30/0x70 fs/iomap/direct-io.c:605
 ext4_dio_write_iter fs/ext4/file.c:548 [inline]
 ext4_file_write_iter+0xe3d/0x10b0 fs/ext4/file.c:658
 call_write_iter include/linux/fs.h:1887 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:721
 do_iter_write+0x112/0x4b0 fs/read_write.c:847
 vfs_iter_write+0x4c/0x70 fs/read_write.c:888
 iter_file_splice_write+0x42a/0x780 fs/splice.c:769
 do_splice_from fs/splice.c:865 [inline]
 direct_splice_actor+0x95/0x150 fs/splice.c:1035
 splice_direct_to_actor+0x365/0x660 fs/splice.c:990
 do_splice_direct+0xf5/0x170 fs/splice.c:1078
 do_sendfile+0x574/0xb70 fs/read_write.c:1238
 __do_sys_sendfile64 fs/read_write.c:1299 [inline]
 __se_sys_sendfile64 fs/read_write.c:1285 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1285
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888009681238 of 8 bytes by task 30370 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1660 [inline]
 xas_next_marked include/linux/xarray.h:1691 [inline]
 find_get_pages_range_tag+0x35c/0x600 mm/filemap.c:2094
 pagevec_lookup_range_tag+0x37/0x50 mm/swap.c:1161
 mpage_prepare_extent_to_map+0x18a/0x630 fs/ext4/inode.c:2558
 ext4_writepages+0x672/0x1e10 fs/ext4/inode.c:2735
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:422
 file_write_and_wait_range+0x9f/0x120 mm/filemap.c:761
 ext4_sync_file+0xfc/0x690 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2725 [inline]
 ext4_buffered_write_iter+0x363/0x3b0 fs/ext4/file.c:276
 ext4_file_write_iter+0x480/0x10b0 fs/ext4/file.c:501
 call_write_iter include/linux/fs.h:1887 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:721
 do_iter_write+0x112/0x4b0 fs/read_write.c:847
 vfs_iter_write+0x4c/0x70 fs/read_write.c:888
 iter_file_splice_write+0x42a/0x780 fs/splice.c:769
 do_splice_from fs/splice.c:865 [inline]
 direct_splice_actor+0x95/0x150 fs/splice.c:1035
 splice_direct_to_actor+0x365/0x660 fs/splice.c:990
 do_splice_direct+0xf5/0x170 fs/splice.c:1078
 do_sendfile+0x574/0xb70 fs/read_write.c:1238
 __do_sys_sendfile64 fs/read_write.c:1299 [inline]
 __se_sys_sendfile64 fs/read_write.c:1285 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1285
 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: 0 PID: 30370 Comm: syz-executor.5 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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