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BUG: KCSAN: data-race in __mark_inode_dirty / writeback_single_inode

write to 0xffff8881160cf770 of 8 bytes by task 661 on cpu 0:
 writeback_single_inode+0x10e/0x4a0 fs/fs-writeback.c:1721
 sync_inode_metadata+0x56/0x80 fs/fs-writeback.c:2780
 __generic_file_fsync+0xf9/0x140 fs/libfs.c:1138
 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:2469 [inline]
 generic_file_write_iter+0x191/0x1c0 mm/filemap.c:4093
 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:795
 do_splice_from fs/splice.c:873 [inline]
 direct_splice_actor+0x84/0xa0 fs/splice.c:1039
 splice_direct_to_actor+0x2ee/0x5f0 fs/splice.c:994
 do_splice_direct+0x104/0x180 fs/splice.c:1082
 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 0xffff8881160cf770 of 8 bytes by task 674 on cpu 1:
 __mark_inode_dirty+0x199/0x7d0 fs/fs-writeback.c:2446
 fat_update_time+0x28e/0x2c0 fs/fat/misc.c:359
 inode_update_time fs/inode.c:1871 [inline]
 touch_atime+0x18c/0x310 fs/inode.c:1944
 file_accessed include/linux/fs.h:2198 [inline]
 generic_file_splice_read+0x13b/0x290 fs/splice.c:422
 do_splice_to fs/splice.c:902 [inline]
 splice_direct_to_actor+0x25a/0x5f0 fs/splice.c:973
 do_splice_direct+0x104/0x180 fs/splice.c:1082
 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: 0x0000000000000007 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 674 Comm: syz-executor.1 Tainted: G        W          6.4.0-rc7-syzkaller-00072-gdad9774deaf1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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