From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleg Nesterov Subject: Re: [PATCH v8 0/7] freezer for cgroup v2 Date: Fri, 22 Feb 2019 17:34:42 +0100 Message-ID: <20190222163441.GA5596@redhat.com> References: <20190219220252.4906-1-guro@fb.com> <20190220143748.GA9477@redhat.com> <20190220220020.GA16335@castle.DHCP.thefacebook.com> <20190221162923.GA26064@redhat.com> <20190221173422.GY50184@devbig004.ftw2.facebook.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20190221173422.GY50184@devbig004.ftw2.facebook.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tejun Heo Cc: Roman Gushchin , Roman Gushchin , Kernel Team , "cgroups@vger.kernel.org" , "linux-kernel@vger.kernel.org" Hi, On 02/21, Tejun Heo wrote: > > So, I really wanna avoid allowing userspace to cause D state sleeps. ... > ptrace support is a lot less important than kill for sure but if at > all possible I think it'd be better to have it Tejun, I agree it would be better. I did not argue with that. The question is how this can be implemented. And how much uglifications^W complications in the core kernel code this needs. > To summarize, the ideal result is the frozen state to be "stuck in > jobctl stop loop" Not sure I understand, but I don't think this can work... Let me repeat, imo the freezer should be "reliable", it shouldn't stuck in CGRP_FREEZE state forever if, say, it races with vfork(). And personally I think this is more important than (very limited) ptrace support. So I think it too should somehow interact with freezable_schedule/etc. Oleg.