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BUG: KCSAN: data-race in __filemap_add_folio / file_write_and_wait_range

write to 0xffff8881330f8300 of 8 bytes by task 9172 on cpu 0:
 __filemap_add_folio+0x256/0x4d0 mm/filemap.c:908
 filemap_add_folio+0x6b/0x150 mm/filemap.c:961
 __filemap_get_folio+0x4c4/0x690 mm/filemap.c:1923
 pagecache_get_page+0x26/0xe0 mm/folio-compat.c:125
 grab_cache_page_write_begin+0x3f/0x50 mm/folio-compat.c:139
 ext4_da_write_begin+0x292/0x4b0 fs/ext4/inode.c:2941
 generic_perform_write+0x1c8/0x400 mm/filemap.c:3687
 ext4_buffered_write_iter+0x19d/0x290 fs/ext4/file.c:268
 ext4_file_write_iter+0x227/0xda0
 call_write_iter include/linux/fs.h:2086 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:725
 do_iter_write+0x192/0x5c0 fs/read_write.c:851
 vfs_iter_write+0x4c/0x70 fs/read_write.c:892
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1245
 __do_sys_sendfile64 fs/read_write.c:1310 [inline]
 __se_sys_sendfile64 fs/read_write.c:1296 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881330f8300 of 8 bytes by task 9179 on cpu 1:
 mapping_needs_writeback mm/filemap.c:634 [inline]
 file_write_and_wait_range+0x4b/0x1d0 mm/filemap.c:785
 ext4_sync_file+0xad/0x570 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:182
 generic_write_sync include/linux/fs.h:2896 [inline]
 ext4_buffered_write_iter+0x243/0x290 fs/ext4/file.c:275
 ext4_file_write_iter+0x227/0xda0
 call_write_iter include/linux/fs.h:2086 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:725
 do_iter_write+0x192/0x5c0 fs/read_write.c:851
 vfs_iter_write+0x4c/0x70 fs/read_write.c:892
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1245
 __do_sys_sendfile64 fs/read_write.c:1310 [inline]
 __se_sys_sendfile64 fs/read_write.c:1296 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000000169 -> 0x000000000000016a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9179 Comm: syz-executor.3 Not tainted 5.16.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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