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BUG: KCSAN: data-race in __mark_inode_dirty / writeback_single_inode

write to 0xffff88812c390540 of 8 bytes by task 5573 on cpu 1:
 writeback_single_inode+0x103/0x3d0 fs/fs-writeback.c:1726
 sync_inode_metadata+0x57/0x80 fs/fs-writeback.c:2749
 __generic_file_fsync+0xf5/0x140 fs/libfs.c:1099
 fat_file_fsync+0x48/0x100 fs/fat/file.c:190
 vfs_fsync_range+0x107/0x120 fs/sync.c:182
 generic_write_sync include/linux/fs.h:2956 [inline]
 generic_file_write_iter+0x103/0x130 mm/filemap.c:3919
 call_write_iter include/linux/fs.h:2162 [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 0xffff88812c390540 of 8 bytes by task 5557 on cpu 0:
 __mark_inode_dirty+0xd7/0x6c0 fs/fs-writeback.c:2420
 fat_update_time+0x125/0x140 fs/fat/misc.c:351
 inode_update_time fs/inode.c:1796 [inline]
 touch_atime+0x16e/0x2e0 fs/inode.c:1869
 file_accessed include/linux/fs.h:2505 [inline]
 generic_file_splice_read+0x2a9/0x330 fs/splice.c:314
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 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: 0x0000000000000001 -> 0x0000000000000080

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5557 Comm: syz-executor.1 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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