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BUG: KCSAN: data-race in vfs_fsync_range / writeback_single_inode

write to 0xffff88810b217730 of 8 bytes by task 15471 on cpu 1:
 writeback_single_inode+0x10e/0x4a0 fs/fs-writeback.c:1716
 sync_inode_metadata+0x56/0x80 fs/fs-writeback.c:2775
 __generic_file_fsync+0xf9/0x140 fs/libfs.c:1143
 fat_file_fsync+0x4c/0x100 fs/fat/file.c:191
 vfs_fsync_range+0x10b/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2885 [inline]
 generic_file_write_iter+0x191/0x1c0 mm/filemap.c:3936
 do_iter_write+0x418/0x700 fs/read_write.c:861
 vfs_iter_write+0x50/0x70 fs/read_write.c:902
 iter_file_splice_write+0x42b/0x7b0 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x84/0xa0 fs/splice.c:931
 splice_direct_to_actor+0x2ee/0x5f0 fs/splice.c:886
 do_splice_direct+0x104/0x180 fs/splice.c:974
 do_sendfile+0x3b8/0x950 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1309
 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 0xffff88810b217730 of 8 bytes by task 15479 on cpu 0:
 vfs_fsync_range+0x9c/0x120 fs/sync.c:186
 generic_write_sync include/linux/fs.h:2885 [inline]
 generic_file_write_iter+0x191/0x1c0 mm/filemap.c:3936
 do_iter_write+0x418/0x700 fs/read_write.c:861
 vfs_iter_write+0x50/0x70 fs/read_write.c:902
 iter_file_splice_write+0x42b/0x7b0 fs/splice.c:686
 do_splice_from fs/splice.c:764 [inline]
 direct_splice_actor+0x84/0xa0 fs/splice.c:931
 splice_direct_to_actor+0x2ee/0x5f0 fs/splice.c:886
 do_splice_direct+0x104/0x180 fs/splice.c:974
 do_sendfile+0x3b8/0x950 fs/read_write.c:1255
 __do_sys_sendfile64 fs/read_write.c:1323 [inline]
 __se_sys_sendfile64 fs/read_write.c:1309 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1309
 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: 0x0000000000000007 -> 0x0000000000000084

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15479 Comm: syz-executor.2 Not tainted 6.2.0-rc8-syzkaller-00098-gec35307e18ba-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023
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