From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 1/5] cgroup, cpuset: replace move_member_tasks_to_cpuset() with cgroup_transfer_tasks() Date: Thu, 4 Apr 2013 16:36:25 -0700 Message-ID: <1365118589-10619-2-git-send-email-tj@kernel.org> References: <1365118589-10619-1-git-send-email-tj@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:sender:from:to:cc:subject:date:message-id:x-mailer :in-reply-to:references; bh=vYTg46NIUW8YdGd6WfgN7p61tvZIc+w1ZvEcxUooFqI=; b=IJuSc43LOk0pHanYBbXkw4ttU8HRuUigvtuUJcmlVCXeQ2pBzoyN4+5GcqQPqj1LD+ N61rRbsMnunudI+kPGN8LbY9IJ12RVAfCayJkOOLGu7NzbftFNHut9+hAqN2sccBn4QK qJGAKeTtOlRM0i3UDFHhGbBvq+zCPBi/V/vXWU+hSGfPbtS/TrVyJ8hvBta7sUtcilG5 j2ubsTkYzaXD6L+QXOemfA1PboPIzbeXW8sm3w/y5U0Hpe+ccJWCrrwPPh989RftJbLs yLAlhEhtpw2mXmIz6FMQPMnumUOCLVrenP/ok6zSgeG9HmRibP5tt4tN6XRCSBxclbqT Kkcw== In-Reply-To: <1365118589-10619-1-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org Cc: Tejun Heo , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org When a cpuset becomes empty (no CPU or memory), its tasks are transferred with the nearest ancestor with execution resources. This is implemented using cgroup_scan_tasks() with a callback which grabs cgroup_mutex and invokes cgroup_attach_task() on each task. Both cgroup_mutex and cgroup_attach_task() are scheduled to be unexported. Implement cgroup_transfer_tasks() in cgroup proper which is essentially the same as move_member_tasks_to_cpuset() except that it takes cgroups instead of cpusets and @to comes before @from like normal functions with those arguments, and replace move_member_tasks_to_cpuset() with it. Signed-off-by: Tejun Heo Cc: Li Zefan --- include/linux/cgroup.h | 1 + kernel/cgroup.c | 28 +++++++++++++++++++++++++++ kernel/cpuset.c | 51 ++++++-------------------------------------------- 3 files changed, 35 insertions(+), 45 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 01c48c6..f8eb01d 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -696,6 +696,7 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan); int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk, bool threadgroup); int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); +int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); /* * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 4aee5bd..147d7cc 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3269,6 +3269,34 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan) return 0; } +static void cgroup_transfer_one_task(struct task_struct *task, + struct cgroup_scanner *scan) +{ + struct cgroup *new_cgroup = scan->data; + + cgroup_lock(); + cgroup_attach_task(new_cgroup, task, false); + cgroup_unlock(); +} + +/** + * cgroup_trasnsfer_tasks - move tasks from one cgroup to another + * @to: cgroup to which the tasks will be moved + * @from: cgroup in which the tasks currently reside + */ +int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) +{ + struct cgroup_scanner scan; + + scan.cg = from; + scan.test_task = NULL; /* select all tasks in cgroup */ + scan.process_task = cgroup_transfer_one_task; + scan.heap = NULL; + scan.data = to; + + return cgroup_scan_tasks(&scan); +} + /* * Stuff for reading the 'tasks'/'procs' files. * diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 98d458a..866d78e 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1994,50 +1994,6 @@ int __init cpuset_init(void) return 0; } -/** - * cpuset_do_move_task - move a given task to another cpuset - * @tsk: pointer to task_struct the task to move - * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner - * - * Called by cgroup_scan_tasks() for each task in a cgroup. - * Return nonzero to stop the walk through the tasks. - */ -static void cpuset_do_move_task(struct task_struct *tsk, - struct cgroup_scanner *scan) -{ - struct cgroup *new_cgroup = scan->data; - - cgroup_lock(); - cgroup_attach_task(new_cgroup, tsk, false); - cgroup_unlock(); -} - -/** - * move_member_tasks_to_cpuset - move tasks from one cpuset to another - * @from: cpuset in which the tasks currently reside - * @to: cpuset to which the tasks will be moved - * - * Called with cpuset_mutex held - * callback_mutex must not be held, as cpuset_attach() will take it. - * - * The cgroup_scan_tasks() function will scan all the tasks in a cgroup, - * calling callback functions for each. - */ -static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to) -{ - struct cgroup_scanner scan; - - scan.cg = from->css.cgroup; - scan.test_task = NULL; /* select all tasks in cgroup */ - scan.process_task = cpuset_do_move_task; - scan.heap = NULL; - scan.data = to->css.cgroup; - - if (cgroup_scan_tasks(&scan)) - printk(KERN_ERR "move_member_tasks_to_cpuset: " - "cgroup_scan_tasks failed\n"); -} - /* * If CPU and/or memory hotplug handlers, below, unplug any CPUs * or memory nodes, we need to walk over the cpuset hierarchy, @@ -2058,7 +2014,12 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs) nodes_empty(parent->mems_allowed)) parent = parent_cs(parent); - move_member_tasks_to_cpuset(cs, parent); + if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) { + rcu_read_lock(); + printk(KERN_ERR "cpuset: failed to transfer tasks out of empty cpuset %s\n", + cgroup_name(cs->css.cgroup)); + rcu_read_unlock(); + } } /** -- 1.8.1.4