Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763552AbZAUEjj (ORCPT ); Tue, 20 Jan 2009 23:39:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756962AbZAUEj3 (ORCPT ); Tue, 20 Jan 2009 23:39:29 -0500 Received: from qw-out-2122.google.com ([74.125.92.26]:58662 "EHLO qw-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756782AbZAUEj2 (ORCPT ); Tue, 20 Jan 2009 23:39:28 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=fdPbukUFskJzwQ1kbJmH/ehpp8dQuLM1Uy91yWiESjgQohVxuDqrlcMOKVU2O2I1gF 51xsk8JcIQ+BwlJIwHoUb8v7I++yjhRL8vl6wAjyX7CXrSj/65RIKf8r0+PDtUlPPvwG lS43nJjIhDXth3yFjwGUwmb5tHLA71dO6PBVI= MIME-Version: 1.0 In-Reply-To: <20090117202638.GA11825@us.ibm.com> References: <20090117202638.GA11825@us.ibm.com> Date: Tue, 20 Jan 2009 23:39:27 -0500 Message-ID: <3e8340490901202039r1ac7e0te5372690dfe81089@mail.gmail.com> Subject: Re: [PATCH 0/7][v7] Container-init signal semantics From: Bryan Donlan To: Sukadev Bhattiprolu Cc: oleg@redhat.com, ebiederm@xmission.com, roland@redhat.com, bastian@waldi.eu.org, daniel@hozac.com, xemul@openvz.org, containers@lists.osdl.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1891 Lines: 40 On Sat, Jan 17, 2009 at 3:26 PM, Sukadev Bhattiprolu wrote: > > Container-init must behave like global-init to processes within the > container and hence it must be immune to unhandled fatal signals from > within the container (i.e SIG_DFL signals that terminate the process). > > But the same container-init must behave like a normal process to > processes in ancestor namespaces and so if it receives the same fatal > signal from a process in ancestor namespace, the signal must be > processed. > > Implementing these semantics requires that send_signal() determine pid > namespace of the sender but since signals can originate from workqueues/ > interrupt-handlers, determining pid namespace of sender may not always > be possible or safe. > > This patchset implements the design/simplified semantics suggested by > Oleg Nesterov. The simplified semantics for container-init are: > > - container-init must never be terminated by a signal from a > descendant process. > > - container-init must never be immune to SIGKILL from an ancestor > namespace (so a process in parent namespace must always be able > to terminate a descendant container). > > - container-init may be immune to unhandled fatal signals (like > SIGUSR1) even if they are from ancestor namespace (SIGKILL is > the only reliable signal from ancestor namespace). SIGSTOP is normally uncatchable; I note that patch 4 states that SIGSTOP is allowed through to container-init, but given this summary is SIGSTOP still reliable when sent to a container-init from an ancestor namespace? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/