So the kernel is enforcing file sharing rules (mandatory locking, in effect) by scanning on open all open file handles for conflicting mandatory locks, but does

So the kernel is enforcing file sharing rules (mandatory locking, in effect) by scanning on open all open file handles for conflicting mandatory locks, but doesn't check for memory mappings of these files with conflicting permissions. Oops. Seems like a straightforward fix though. It's worth noting that Linux just got rid of its last vestige of mandatory locking. Now you can write a loaded executable without getting EBUSY. Interesting how exactly the same feature on one OS can be a load bearing part of the security infrastructure and on another OS legacy crud to be deleted.