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Tue, 20 Nov 2018 08:25:31 -0800 (PST) Date: Tue, 20 Nov 2018 08:25:29 -0800 From: Tejun Heo To: Roman Gushchin Cc: Oleg Nesterov , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, Roman Gushchin Subject: Re: [PATCH v3 4/7] cgroup: cgroup v2 freezer Message-ID: <20181120162529.GU2509588@devbig004.ftw2.facebook.com> References: <20181117003830.15344-1-guro@fb.com> <20181117003830.15344-5-guro@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181117003830.15344-5-guro@fb.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 16, 2018 at 04:38:27PM -0800, Roman Gushchin wrote: > +void cgroup_freezer_migrate_task(struct task_struct *task, > + struct cgroup *src, struct cgroup *dst) > +{ > + lockdep_assert_held(&css_set_lock); > + > + /* > + * Kernel threads are not supposed to be frozen at all. > + */ > + if (task->flags & PF_KTHREAD) > + return; > + > + /* > + * Adjust counters of freezing and frozen tasks. > + */ > + if (test_bit(CGRP_FREEZE, &src->flags)) { > + src->freezer.nr_tasks_to_freeze--; > + WARN_ON_ONCE(src->freezer.nr_tasks_to_freeze < 0); > + } > + > + /* > + * If the task is frozen, let's bump nr_tasks_to_freeze even > + * if the target cgroup isn't frozen: the counter will be decreased > + * in cgroup_leave_frozen(). > + */ > + if (test_bit(CGRP_FREEZE, &dst->flags) || task->frozen) > + dst->freezer.nr_tasks_to_freeze++; > + > + if (task->frozen) { > + src->freezer.nr_frozen_tasks--; > + dst->freezer.nr_frozen_tasks++; > + WARN_ON_ONCE(src->freezer.nr_frozen_tasks < 0); > + WARN_ON_ONCE(dst->freezer.nr_frozen_tasks > > + dst->freezer.nr_tasks_to_freeze); > + } If a non-frozen task is being moved into a frozen cgroup, shouldn't that also trigger frozen state update? Thanks. -- tejun