[RHEL7,v14,08/12] ve/cgroup: moved release_agent from system_wq to per-ve workqueues

Submitted by Valeriy Vdovin on April 21, 2020, 12:53 p.m.

Details

Message ID 1587473629-182085-9-git-send-email-valeriy.vdovin@virtuozzo.com
State New
Series "Make release_agent per-cgroup property. Run release_agent in proper ve."
Headers show

Commit Message

Valeriy Vdovin April 21, 2020, 12:53 p.m.
Each VE should execute release agent notifications within it's own
workqueue. This way we achieve a more fine-grained control over
release_agent work flushing at VE destruction.

Signed-off-by: Valeriy Vdovin <valeriy.vdovin@virtuozzo.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
 include/linux/cgroup.h |  1 +
 include/linux/ve.h     | 10 +++++++++
 kernel/cgroup.c        | 55 +++++++++++++++++++++++---------------------------
 kernel/ve/ve.c         | 44 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 80 insertions(+), 30 deletions(-)

Patch hide | download patch | download mbox

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 7ed718d..d0ce3cc 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -636,6 +636,7 @@  int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen);
 int cgroup_path_ve(const struct cgroup *cgrp, char *buf, int buflen);
 
 int cgroup_task_count(const struct cgroup *cgrp);
+void cgroup_release_agent(struct work_struct *work);
 
 #ifdef CONFIG_VE
 void cgroup_mark_ve_roots(struct ve_struct *ve);
diff --git a/include/linux/ve.h b/include/linux/ve.h
index 02e00e9..787a96f 100644
--- a/include/linux/ve.h
+++ b/include/linux/ve.h
@@ -126,7 +126,15 @@  struct ve_struct {
 #endif
 	struct kmapset_key	sysfs_perms_key;
 
+	/*
+	 * cgroups, that want to notify about becoming
+	 * empty, are linked to this release_list.
+	 */
+	struct list_head	release_list;
+	struct raw_spinlock	release_list_lock;
+
 	struct workqueue_struct	*wq;
+	struct work_struct	release_agent_work;
 
 	/*
 	 * All tasks, that belong to this ve, live
@@ -197,6 +205,8 @@  call_usermodehelper_ve(struct ve_struct *ve, char *path, char **argv,
 }
 void do_update_load_avg_ve(void);
 
+void ve_add_to_release_list(struct cgroup *cgrp);
+void ve_rm_from_release_list(struct cgroup *cgrp);
 extern struct ve_struct *get_ve(struct ve_struct *ve);
 extern void put_ve(struct ve_struct *ve);
 
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index b19d749..6437344 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -269,10 +269,6 @@  static bool cgroup_lock_live_group(struct cgroup *cgrp)
 
 /* the list of cgroups eligible for automatic release. Protected by
  * release_list_lock */
-static LIST_HEAD(release_list);
-static DEFINE_RAW_SPINLOCK(release_list_lock);
-static void cgroup_release_agent(struct work_struct *work);
-static DECLARE_WORK(release_agent_work, cgroup_release_agent);
 static void check_for_release(struct cgroup *cgrp);
 
 /* Link structure for associating css_set objects with cgroups */
@@ -4316,6 +4312,15 @@  void cgroup_unmark_ve_roots(struct ve_struct *ve)
 	mutex_unlock(&cgroup_mutex);
 	/* ve_owner == NULL will be visible */
 	synchronize_rcu();
+
+	/*
+	 * Anyone already waiting in this wq to execute
+	 * cgroup_release_agent doesn't know that ve_owner is NULL,
+	 * but we can wait for all of them at flush_workqueue.
+	 * After it is complete no other cgroup can seep through
+	 * to this ve's workqueue, so it's safe to shutdown ve.
+	 */
+	flush_workqueue(ve->wq);
 }
 
 struct cgroup *cgroup_get_ve_root(struct cgroup *cgrp)
@@ -4610,11 +4615,7 @@  static int cgroup_destroy_locked(struct cgroup *cgrp)
 
 	set_bit(CGRP_REMOVED, &cgrp->flags);
 
-	raw_spin_lock(&release_list_lock);
-	if (!list_empty(&cgrp->release_list))
-		list_del_init(&cgrp->release_list);
-	raw_spin_unlock(&release_list_lock);
-
+	ve_rm_from_release_list(cgrp);
 	/*
 	 * Remove @cgrp directory.  The removal puts the base ref but we
 	 * aren't quite done with @cgrp yet, so hold onto it.
@@ -5398,17 +5399,7 @@  static void check_for_release(struct cgroup *cgrp)
 		 * already queued for a userspace notification, queue
 		 * it now
 		 */
-		int need_schedule_work = 0;
-
-		raw_spin_lock(&release_list_lock);
-		if (!cgroup_is_removed(cgrp) &&
-		    list_empty(&cgrp->release_list)) {
-			list_add(&cgrp->release_list, &release_list);
-			need_schedule_work = 1;
-		}
-		raw_spin_unlock(&release_list_lock);
-		if (need_schedule_work)
-			schedule_work(&release_agent_work);
+		ve_add_to_release_list(cgrp);
 	}
 }
 
@@ -5435,20 +5426,24 @@  static void check_for_release(struct cgroup *cgrp)
  * this routine has no use for the exit status of the release agent
  * task, so no sense holding our caller up for that.
  */
-static void cgroup_release_agent(struct work_struct *work)
+void cgroup_release_agent(struct work_struct *work)
 {
-	BUG_ON(work != &release_agent_work);
+	struct ve_struct *ve;
+	ve = container_of(work, struct ve_struct, release_agent_work);
 	mutex_lock(&cgroup_mutex);
-	raw_spin_lock(&release_list_lock);
-	while (!list_empty(&release_list)) {
+	raw_spin_lock(&ve->release_list_lock);
+	while (!list_empty(&ve->release_list)) {
 		char *argv[3], *envp[3];
 		int i, err;
 		char *pathbuf = NULL, *agentbuf = NULL;
-		struct cgroup *cgrp = list_entry(release_list.next,
-						    struct cgroup,
-						    release_list);
+		struct cgroup *cgrp;
+
+		cgrp = list_entry(ve->release_list.next,
+				  struct cgroup,
+				  release_list);
+
 		list_del_init(&cgrp->release_list);
-		raw_spin_unlock(&release_list_lock);
+		raw_spin_unlock(&ve->release_list_lock);
 		pathbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 		if (!pathbuf)
 			goto continue_free;
@@ -5483,9 +5478,9 @@  static void cgroup_release_agent(struct work_struct *work)
  continue_free:
 		kfree(pathbuf);
 		kfree(agentbuf);
-		raw_spin_lock(&release_list_lock);
+		raw_spin_lock(&ve->release_list_lock);
 	}
-	raw_spin_unlock(&release_list_lock);
+	raw_spin_unlock(&ve->release_list_lock);
 	mutex_unlock(&cgroup_mutex);
 }
 
diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
index db3b600..eb266ae 100644
--- a/kernel/ve/ve.c
+++ b/kernel/ve/ve.c
@@ -87,6 +87,11 @@  struct ve_struct ve0 = {
 	.netif_max_nr		= INT_MAX,
 	.arp_neigh_nr		= ATOMIC_INIT(0),
 	.nd_neigh_nr		= ATOMIC_INIT(0),
+	.release_list_lock	= __RAW_SPIN_LOCK_UNLOCKED(
+					ve0.release_list_lock),
+	.release_list		= LIST_HEAD_INIT(ve0.release_list),
+	.release_agent_work	= __WORK_INITIALIZER(ve0.release_agent_work,
+					cgroup_release_agent),
 };
 EXPORT_SYMBOL(ve0);
 
@@ -498,6 +503,41 @@  static void ve_workqueue_stop(struct ve_struct *ve)
 	destroy_workqueue(ve->wq);
 }
 
+void ve_add_to_release_list(struct cgroup *cgrp)
+{
+	struct ve_struct *ve;
+	int need_schedule_work = 0;
+
+	rcu_read_lock();
+	ve = cgroup_get_ve_owner(cgrp);
+
+	raw_spin_lock(&ve->release_list_lock);
+	if (!cgroup_is_removed(cgrp) &&
+	    list_empty(&cgrp->release_list)) {
+		list_add(&cgrp->release_list, &ve->release_list);
+		need_schedule_work = 1;
+	}
+	raw_spin_unlock(&ve->release_list_lock);
+
+	if (need_schedule_work)
+		queue_work(ve->wq, &ve->release_agent_work);
+
+	rcu_read_unlock();
+}
+
+void ve_rm_from_release_list(struct cgroup *cgrp)
+{
+	struct ve_struct *ve;
+	rcu_read_lock();
+	ve = cgroup_get_ve_owner(cgrp);
+
+	raw_spin_lock(&ve->release_list_lock);
+	if (!list_empty(&cgrp->release_list))
+		list_del_init(&cgrp->release_list);
+	raw_spin_unlock(&ve->release_list_lock);
+	rcu_read_unlock();
+}
+
 /* under ve->op_sem write-lock */
 static int ve_start_container(struct ve_struct *ve)
 {
@@ -693,6 +733,9 @@  static struct cgroup_subsys_state *ve_create(struct cgroup *cg)
 	if (!ve->ve_name)
 		goto err_name;
 
+	INIT_WORK(&ve->release_agent_work, cgroup_release_agent);
+	raw_spin_lock_init(&ve->release_list_lock);
+
 	ve->_randomize_va_space = ve0._randomize_va_space;
 
 	ve->features = VE_FEATURES_DEF;
@@ -727,6 +770,7 @@  do_init:
 	INIT_LIST_HEAD(&ve->devices);
 	INIT_LIST_HEAD(&ve->ve_list);
 	INIT_LIST_HEAD(&ve->devmnt_list);
+	INIT_LIST_HEAD(&ve->release_list);
 	mutex_init(&ve->devmnt_mutex);
 
 #ifdef CONFIG_AIO