From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1, USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 28105C4332B for ; Fri, 20 Mar 2020 20:10:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E607E20714 for ; Fri, 20 Mar 2020 20:10:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="fvAklPMv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726829AbgCTUKp (ORCPT ); Fri, 20 Mar 2020 16:10:45 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:46523 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726773AbgCTUKp (ORCPT ); Fri, 20 Mar 2020 16:10:45 -0400 Received: by mail-pf1-f196.google.com with SMTP id c19so3838347pfo.13 for ; Fri, 20 Mar 2020 13:10:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=8wBJM863apF0IwOPmO9fuaOOqzaQw306izkJnc0/fII=; b=fvAklPMvJlNS9vNQhJdK1AuiQZmkjC9vvIRMZAQNcvfDDWR0w81khYqp5RiIul11WS WNDSy3c75Luwy9fag1iFfAx9/w70boBzrfy11P7KavWhZ+KyL4ceLQOJRHR1B3zrPJUZ qdClxBt0eYYcn70/mYeISAvctswbPnd48V7CRpzrwo3NX8m/mAo6R6EhXlXVD9++v7TH uYxvLdjJRlOBxjGld2ZPPSL3GxoFznoZ8mkQV+c9Q3N7U+vOYd5Lmjf43xm/r76g91X/ AUhtUkfSWDvveqHe5UZzR9+cCVaNJjrJ+Pco0WFaX1iLxXn9O15Mu5/ruLY0L6YUn2/+ 4ONQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=8wBJM863apF0IwOPmO9fuaOOqzaQw306izkJnc0/fII=; b=YGjWdVlnuFOgtVu0lwMw5IFk2VgVITI71M59j3650hms9DGnEd8+FkXVY9c7fW7WBR pncrp9z5kHlfdqOnqyZtcckIUALGg5kql/qM/CeKEw9/HtVvkTFS7tGkTANr817GS+Lr W/tlHQ5bcYRWTZ31xBne0hyVK6hlsblhK2c6LomR+EiE8gbztX6U43pBo8BnT3FSG9sP lxJP8FmmKmlsBeGaKP5Le4/D/G+n2ufv+CYI61G6tRx1qM9t1txB6KI14XrcsaWtMIan jprAUoS5WPxO82rrVEH53OyH52Jnd3q1dPzQzdjVYyJbEzkoHuq+XkLQh9KFHrZqw8vz qfpA== X-Gm-Message-State: ANhLgQ3eOXGMpep4ixzaLB7GX5HpQhsWZprXPQj7dZm7C5kiWoA5ZiJM jO/F123J4mnepJ9WJSt+xy7a/A== X-Google-Smtp-Source: ADFU+vt4bqdyXNnRbChIEYqGnF9tjkMzkpQ2TcoyY685E+bmpfFRtb9zrOeEKlZxBHUT4jtOCkI9MQ== X-Received: by 2002:a63:4d6:: with SMTP id 205mr10113365pge.10.1584735044151; Fri, 20 Mar 2020 13:10:44 -0700 (PDT) Received: from google.com ([2620:15c:211:202:ae26:61fb:e2f3:92e7]) by smtp.gmail.com with ESMTPSA id t142sm5878431pgb.31.2020.03.20.13.10.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Mar 2020 13:10:43 -0700 (PDT) Date: Fri, 20 Mar 2020 13:10:38 -0700 From: Marco Ballesio To: Daniel Colascione Cc: Tejun Heo , Roman Gushchin , cgroups@vger.kernel.org, linux-kernel , lizefan@huawei.com, Johannes Weiner , Jonathan Corbet , rjw@rjwysocki.net, Pavel Machek , len.brown@intel.com, "open list:DOCUMENTATION" , linux-pm@vger.kernel.org, Minchan Kim , Suren Baghdasaryan Subject: Re: [PATCH] cgroup-v1: freezer: optionally killable freezer Message-ID: <20200320201038.GB79184@google.com> References: <20200219183231.50985-1-balejs@google.com> <20200303134855.GA186184@mtj.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Wed, Mar 11, 2020 at 10:46:15AM -0700, Daniel Colascione wrote: > On Tue, Mar 3, 2020 at 5:48 AM Tejun Heo wrote: > > > > Hello, > > > > On Wed, Feb 19, 2020 at 10:32:31AM -0800, Marco Ballesio wrote: > > > @@ -94,6 +94,18 @@ The following cgroupfs files are created by cgroup freezer. > > > Shows the parent-state. 0 if none of the cgroup's ancestors is > > > frozen; otherwise, 1. > > > > > > +* freezer.killable: Read-write > > > + > > > + When read, returns the killable state of a cgroup - "1" if frozen > > > + tasks will respond to fatal signals, or "0" if they won't. > > > + > > > + When written, this property sets the killable state of the cgroup. > > > + A value equal to "1" will switch the state of all frozen tasks in > > > + the cgroup to TASK_INTERRUPTIBLE (similarly to cgroup v2) and will > > > + make them react to fatal signals. A value of "0" will switch the > > > + state of frozen tasks to TASK_UNINTERRUPTIBLE and they won't respond > > > + to signals unless thawed or unfrozen. > > > > As Roman said, I'm not too sure about adding a new cgroup1 freezer > > interface at this point. If we do this, *maybe* a mount option would > > be more minimal? > > I'd still prefer a cgroup flag. A mount option is a bigger > compatibility risk and isn't really any simpler than another cgroup > flag. A mount option will affect anything using the cgroup mount > point, potentially turning non-killable frozen processes into killable > ones unexpectedly. (Sure, you could mount multiple times, but only one > location is canonical, and that's the one that's going to get the flag > flipped.) A per-cgroup flag allows people to opt into the new behavior > only in specific contexts, so it's safer. It might also be desirable for userland to have a way to modify the behavior of an already mounted v1 freezer. Tejun, would it be acceptable to have a flag but disable it by default, hiding it behind a kernel configuration option?