I'm seeing some odd behavior which may be a bug. I've broken it down to a least common denominator to reproduce it. But maybe I'm doing something wrong. I am opening a file read-write. I'm then mapping the file read-only and private: void* pointer = mmap(NULL, 17, PROT_READ, MAP_FILE | MAP_PRIVATE, fd, 0); I then unmap the memory and close the file. After the close, eslogger shows me this: {"close":{"modified":false,[...],"was_mapped_writable":false}} Which makes sense. I then change the mmap statement to: void* pointer = mmap(NULL, 17, PROT_READ, MAP_FILE | MAP_SHARED, fd, 0); I run the new code and and the close looks like: {"close":{"modified":false, [....], "was_mapped_writable":true}} Which also makes sense. I then run the original again (ie, with MAP_PRIVATE vs. MAP_SHARED) and the close looks like: {"close":{"modified":false,"was_mapped_writable":true,[...]} Which doesn't appear to be correct. Now if I just open and close the file (again, read-write) and don't mmap anything the close still shows: {"close":{ [...], "was_mapped_writable":true,"modified":false}} And the same is true if I open the file read-only. It will remain that way until I delete the file. If I recreate the file and try again, everything is good until I map it MAP_SHARED. I tried this with macOS 13.6.7 and macOS 15.0.1.