When you use System V shared memory in Linux, you are supposed to use proper locking and synchronization (using sysv semaphores for example) so the code doesn't break when different threads/processes try to read/write the same segment.
Considering that System V shared memory uses a tmpfs under the hood, if you use files in a tmpfs (instead of memory segments) do you have to provide a synchronization mechanims anyways?
Can't you rely on the file system to provide file read/write synchronization?