Posted Jul 25, 2008 20:28 UTC (Fri) by nix (subscriber, #2304)
In reply to: TASK_KILLABLE by mcortese
Parent article: TASK_KILLABLE
If it's in KILLABLE state, it *does* know how to deal with signals within
the kernel, and its in-kernel state can be cleanly unwound. The reason
that this doesn't propagate up to userspace as an EINTR is simply that
there is in effect a Unix guarantee that filesystem operations cannot be
interrupted, and the vast majority of userspace code relies on this
guarantee and will malfunction if it starts getting EINTRs from tasks.
(This is what the old 'intr' option did, and boy were the results messy.)
That's why it only responds to SIGKILL: because SIGKILL, by definition,
doesn't get propagated to userspace, because the process's userspace
component is killed by the SIGKILL.