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BUG: KCSAN: data-race in vfs_fsync_range / writeback_single_inode

write to 0xffff888109a0e380 of 8 bytes by task 4633 on cpu 0:
 writeback_single_inode+0x10e/0x4a0 fs/fs-writeback.c:1721
 sync_inode_metadata+0x56/0x80 fs/fs-writeback.c:2780
 ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
 ext4_sync_file+0x319/0x6e0 fs/ext4/fsync.c:161
 vfs_fsync_range+0x10b/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2469 [inline]
 ext4_buffered_write_iter+0x397/0x3e0 fs/ext4/file.c:296
 ext4_file_write_iter+0xd7/0x10e0
 do_iter_write+0x4ae/0x770 fs/read_write.c:860
 vfs_iter_write+0x50/0x70 fs/read_write.c:901
 iter_file_splice_write+0x456/0x7d0 fs/splice.c:779
 do_splice_from fs/splice.c:857 [inline]
 direct_splice_actor+0x84/0xa0 fs/splice.c:1023
 splice_direct_to_actor+0x2ee/0x5f0 fs/splice.c:978
 do_splice_direct+0x104/0x180 fs/splice.c:1066
 do_sendfile+0x3b8/0x950 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888109a0e380 of 8 bytes by task 4629 on cpu 1:
 vfs_fsync_range+0x9c/0x120 fs/sync.c:186
 generic_write_sync include/linux/fs.h:2469 [inline]
 ext4_buffered_write_iter+0x397/0x3e0 fs/ext4/file.c:296
 ext4_file_write_iter+0xd7/0x10e0
 do_iter_write+0x4ae/0x770 fs/read_write.c:860
 vfs_iter_write+0x50/0x70 fs/read_write.c:901
 iter_file_splice_write+0x456/0x7d0 fs/splice.c:779
 do_splice_from fs/splice.c:857 [inline]
 direct_splice_actor+0x84/0xa0 fs/splice.c:1023
 splice_direct_to_actor+0x2ee/0x5f0 fs/splice.c:978
 do_splice_direct+0x104/0x180 fs/splice.c:1066
 do_sendfile+0x3b8/0x950 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000804 -> 0x0000000000000084

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4629 Comm: syz-executor.4 Not tainted 6.3.0-syzkaller-12049-g58390c8ce1bd #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
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