On 10/28, Pedro Alves wrote: > > On 10/28/2015 04:11 PM, Oleg Nesterov wrote: > > On 10/26, Pedro Alves wrote: > >> > >> (Also, in the original test case, if the child gets/raises a signal or > >> execs > >> before exiting, the bash/init/whatever process won't be issuing > >> PTRACE_CONT, > >> and the child will thus end up stuck (though should be SIGKILLable, > > > > Oh, but if it is killable everything is fine. How does this differ from the > > case when, say, you jusr reparent to init and do kill(getpid(), SIGSTOP) ? > > The difference is that if the child called PTRACE_TRACEME, then it goes > to ptrace-stop instead and no amount of SIGCONT unstucks it -- the only way > out is force killing. I agree it's not a major issue as there's a way out > (and thus made it a parens), but I wouldn't call it nice either.
IOW, the difference is that it is TASK_TRACED, not TASK_STOPPED. I agree, this is not nice. But this is not nice simply because PTRACE_TRACEME is not nice. > >> All this because PTRACE_TRACEME is broken by design > > > > Heh. I agree. But we can't fix it now. > > Perhaps the man page could document it as deprecated, suggesting > PTRACE_ATTACH/PTRACE_SEIZE instead? I don't know. but I won't mind if you mark PTRACE_ATTACH as deprecated too ;) PTRACE_SEIZE can be used instead and it doesn't abuse SIGSTOP. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/