Binaries are memory-mapped, there is no guarantee for code to be resident. Modifying a running binary hence can cause a mixture of code to be paged into a runni

Binaries are memory-mapped, there is no guarantee for code to be resident. Modifying a running binary hence can cause a mixture of code to be paged into a running application. Which is why unix traditionally has a special "non-advisory" file locking for mapped binaries, which tries to give you an ETXTBSY error. This is nowhere near fool-proof though, e.g. Linux stopped doing this for mapped .so files, it probably doesn't work on NFS etc.