It's a new log message (umm, why are you running 1.3.96 if you're not reading linux-kernel@vger.rutgers.edu? it's been hashed to death there...) to catch a certain usage of flock in libc, which should have been fixed around 1.3.10... Apparently the 5.3.x libc has the fix now, but you'll only get that message five times anyway (some systems would get it fairly often, without it really being fixable.)