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BUG: KCSAN: data-race in __add_to_page_cache_locked / file_write_and_wait_range

read-write to 0xffff88810be91b90 of 8 bytes by task 29789 on cpu 1:
 __add_to_page_cache_locked+0x39d/0x7b0 mm/filemap.c:888
 add_to_page_cache_lru+0xa0/0x1b0 mm/filemap.c:939
 page_cache_ra_unbounded+0x272/0x4c0 mm/readahead.c:222
 ondemand_readahead+0x560/0x780 mm/readahead.c:267
 page_cache_async_ra+0x1aa/0x1d0 mm/readahead.c:607
 page_cache_async_readahead include/linux/pagemap.h:862 [inline]
 do_async_mmap_readahead mm/filemap.c:2662 [inline]
 filemap_fault+0x310/0x12e0 mm/filemap.c:2717
 __do_fault mm/memory.c:3612 [inline]
 do_read_fault+0x403/0x760 mm/memory.c:4006
 do_fault mm/memory.c:4134 [inline]
 handle_pte_fault mm/memory.c:4374 [inline]
 __handle_mm_fault mm/memory.c:4509 [inline]
 handle_mm_fault+0xfeb/0x1770 mm/memory.c:4607
 faultin_page mm/gup.c:885 [inline]
 __get_user_pages+0x8ec/0xe50 mm/gup.c:1097
 populate_vma_page_range mm/gup.c:1430 [inline]
 __mm_populate+0x24d/0x340 mm/gup.c:1478
 mm_populate include/linux/mm.h:2590 [inline]
 vm_mmap_pgoff+0x133/0x170 mm/util.c:512
 ksys_mmap_pgoff+0x2a8/0x380 mm/mmap.c:1634
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810be91b90 of 8 bytes by task 29786 on cpu 0:
 mapping_needs_writeback mm/filemap.c:630 [inline]
 file_write_and_wait_range+0x79/0x120 mm/filemap.c:760
 blkdev_fsync+0x42/0xa0 fs/block_dev.c:683
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2723 [inline]
 blkdev_write_iter+0x264/0x2a0 fs/block_dev.c:1907
 call_write_iter include/linux/fs.h:1887 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4b0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x42a/0x780 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:933
 splice_direct_to_actor+0x345/0x650 fs/splice.c:888
 do_splice_direct+0xf5/0x170 fs/splice.c:976
 do_sendfile+0x574/0xb70 fs/read_write.c:1257
 __do_sys_sendfile64 fs/read_write.c:1318 [inline]
 __se_sys_sendfile64 fs/read_write.c:1304 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1304
 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: 29786 Comm: syz-executor.4 Not tainted 5.10.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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