Comment 10 for bug 636278

(In reply to comment #6)
> Ubuntu has added prctl(PR_SET_PTRACER, debugger_pid, 0, 0, 0); as the way to
> declare PTRACE relationships for crash handlers (or wardens). For an example,
> see how kdelibs was patched:
>
> http://launchpadlibrarian.net/51487035/kde4libs_4%3A4.4.90-0ubuntu2_4%3A4.4.90-0ubuntu3.diff.gz
>
> It should be possible for a process to specify which process families are
> allowed to PTRACE it.

Did PR_SET_PTRACER actually make it into the mainline kernel then? 0x59616d61 / "Yama" certainly looks magic.