doing this COW stuff with file mapped pages generally must be kind of weird. like normally with a COW page you just mark the page entry as read only and then wh

doing this COW stuff with file mapped pages generally must be kind of weird. like normally with a COW page you just mark the page entry as read only and then when the process tries to modify the page you create a copy of the page for that process. the only process that is modified is the process that tried to write to the page. but with file mapped pages this is going to be a bit weird because the processes with a file page mapped MAP_SHARED should see others modifications of a MAP_SHARED page and presumably now when process modifies a file mapped page that is marked read only the kernel now has to update all the other processes to point at this new writable page. i think it is easy to modify the current process's page table, not sure how easy it is to modify other process's view of the page table. though, maybe the kernel wouldn't let you RPC a MAP_SHARED mmap. maybe it would only let you do it with a MAP_PRIVATE mmap.