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BUG: KCSAN: data-race in find_get_pages_range_tag / xas_clear_mark

write to 0xffff888130414b38 of 8 bytes by task 9992 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+0xa1/0x180 lib/xarray.c:911
 __test_set_page_writeback+0x3db/0x4f0 mm/page-writeback.c:2802
 ext4_bio_write_page+0xfe/0xe60 fs/ext4/page-io.c:450
 mpage_submit_page fs/ext4/inode.c:2101 [inline]
 mpage_map_and_submit_buffers fs/ext4/inode.c:2349 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2488 [inline]
 ext4_writepages+0xec2/0x1e70 fs/ext4/inode.c:2801
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:424
 filemap_write_and_wait_range+0x8b/0x2a0 mm/filemap.c:657
 ext4_collapse_range+0x2b3/0x760 fs/ext4/extents.c:5293
 ext4_fallocate+0x1f0/0x540 fs/ext4/extents.c:4664
 vfs_fallocate+0x479/0x6d0 fs/open.c:309
 ksys_fallocate fs/open.c:332 [inline]
 __do_sys_fallocate fs/open.c:340 [inline]
 __se_sys_fallocate fs/open.c:338 [inline]
 __x64_sys_fallocate+0x75/0xc0 fs/open.c:338
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888130414b38 of 8 bytes by task 9984 on cpu 1:
 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:2109
 pagevec_lookup_range_tag+0x37/0x50 mm/swap.c:1122
 mpage_prepare_extent_to_map+0x195/0x640 fs/ext4/inode.c:2578
 ext4_writepages+0x97b/0x1e70 fs/ext4/inode.c:2799
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:424
 file_write_and_wait_range+0x9f/0x120 mm/filemap.c:763
 ext4_sync_file+0x105/0x6e0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2760 [inline]
 ext4_buffered_write_iter+0x38f/0x3e0 fs/ext4/file.c:277
 ext4_file_write_iter+0x48a/0x10b0 fs/ext4/file.c:502
 call_write_iter include/linux/fs.h:1901 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6f9/0x7e0 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9984 Comm: syz-executor.2 Not tainted 5.11.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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