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Subject[PATCH 6/6] Lets ss->can_attach and ss->attach do whole threadgroups at a time
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Lets ss->can_attach and ss->attach do whole threadgroups at a time

This patch alters the ss->can_attach and ss->attach functions to be able to
deal with a whole threadgroup at a time, for use in cgroup_attach_proc. (This
is a post-patch to cgroup-procs-writable.patch.)

Signed-off-by: Ben Blum <bblum@google.com>

---
include/linux/cgroup.h | 7 +++--
kernel/cgroup.c | 8 +++---
kernel/cgroup_freezer.c | 15 +++++++++--
kernel/cpuset.c | 65 ++++++++++++++++++++++++++++++++++++----------
kernel/ns_cgroup.c | 16 ++++++++++-
kernel/sched.c | 37 ++++++++++++++++++++++++--
mm/memcontrol.c | 3 +-
security/device_cgroup.c | 3 +-
8 files changed, 124 insertions(+), 30 deletions(-)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index cae7d3e..5a4383c 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -409,10 +409,11 @@ struct cgroup_subsys {
struct cgroup *cgrp);
int (*pre_destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
- int (*can_attach)(struct cgroup_subsys *ss,
- struct cgroup *cgrp, struct task_struct *tsk);
+ int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
+ struct task_struct *tsk, bool threadgroup);
void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct cgroup *old_cgrp, struct task_struct *tsk);
+ struct cgroup *old_cgrp, struct task_struct *tsk,
+ bool threadgroup);
void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
void (*exit)(struct cgroup_subsys *ss, struct task_struct *task);
int (*populate)(struct cgroup_subsys *ss,
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3f8d323..abdfa5a 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1415,7 +1415,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)

for_each_subsys(root, ss) {
if (ss->can_attach) {
- retval = ss->can_attach(ss, cgrp, tsk);
+ retval = ss->can_attach(ss, cgrp, tsk, false);
if (retval)
return retval;
}
@@ -1427,7 +1427,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)

for_each_subsys(root, ss) {
if (ss->attach)
- ss->attach(ss, cgrp, oldcgrp, tsk);
+ ss->attach(ss, cgrp, oldcgrp, tsk, false);
}

synchronize_rcu();
@@ -1537,7 +1537,7 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
*/
for_each_subsys(root, ss) {
if (ss->can_attach) {
- retval = ss->can_attach(ss, cgrp, leader);
+ retval = ss->can_attach(ss, cgrp, leader, true);
if (retval)
return retval;
}
@@ -1649,7 +1649,7 @@ again:
*/
for_each_subsys(root, ss) {
if (ss->attach)
- ss->attach(ss, cgrp, oldcgrp, leader);
+ ss->attach(ss, cgrp, oldcgrp, leader, true);
}

/*
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index fb249e2..4e352ab 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -159,10 +159,9 @@ static bool is_task_frozen_enough(struct task_struct *task)
*/
static int freezer_can_attach(struct cgroup_subsys *ss,
struct cgroup *new_cgroup,
- struct task_struct *task)
+ struct task_struct *task, bool threadgroup)
{
struct freezer *freezer;
-
/*
* Anything frozen can't move or be moved to/from.
*
@@ -177,6 +176,18 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
if (freezer->state == CGROUP_FROZEN)
return -EBUSY;

+ if (threadgroup) {
+ struct task_struct *c;
+ rcu_read_lock();
+ list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
+ if (is_task_frozen_enough(c)) {
+ rcu_read_unlock();
+ return -EBUSY;
+ }
+ }
+ rcu_read_unlock();
+ }
+
return 0;
}

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 7e75a41..86397f4 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1324,9 +1324,10 @@ static int fmeter_getrate(struct fmeter *fmp)
static cpumask_var_t cpus_attach;

/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */
-static int cpuset_can_attach(struct cgroup_subsys *ss,
- struct cgroup *cont, struct task_struct *tsk)
+static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont,
+ struct task_struct *tsk, bool threadgroup)
{
+ int ret;
struct cpuset *cs = cgroup_cs(cont);

if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
@@ -1343,18 +1344,50 @@ static int cpuset_can_attach(struct cgroup_subsys *ss,
if (tsk->flags & PF_THREAD_BOUND)
return -EINVAL;

- return security_task_setscheduler(tsk, 0, NULL);
+ ret = security_task_setscheduler(tsk, 0, NULL);
+ if (ret)
+ return ret;
+ if (threadgroup) {
+ struct task_struct *c;
+ rcu_read_lock();
+ list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
+ ret = security_task_setscheduler(c, 0, NULL);
+ if (ret) {
+ rcu_read_unlock();
+ return ret;
+ }
+ }
+ rcu_read_unlock();
+ }
+ return 0;
+}
+
+static void cpuset_attach_task(struct task_struct *tsk, nodemask_t *to,
+ struct cpuset *cs)
+{
+ int err;
+ /*
+ * can_attach beforehand should guarantee that this doesn't fail.
+ * TODO: have a better way to handle failure here
+ */
+ err = set_cpus_allowed_ptr(tsk, cpus_attach);
+ WARN_ON_ONCE(err);
+
+ task_lock(tsk);
+ cpuset_change_task_nodemask(tsk, to);
+ task_unlock(tsk);
+ cpuset_update_task_spread_flag(cs, tsk);
+
}

-static void cpuset_attach(struct cgroup_subsys *ss,
- struct cgroup *cont, struct cgroup *oldcont,
- struct task_struct *tsk)
+static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont,
+ struct cgroup *oldcont, struct task_struct *tsk,
+ bool threadgroup)
{
nodemask_t from, to;
struct mm_struct *mm;
struct cpuset *cs = cgroup_cs(cont);
struct cpuset *oldcs = cgroup_cs(oldcont);
- int err;

if (cs == &top_cpuset) {
cpumask_copy(cpus_attach, cpu_possible_mask);
@@ -1363,15 +1396,19 @@ static void cpuset_attach(struct cgroup_subsys *ss,
guarantee_online_cpus(cs, cpus_attach);
guarantee_online_mems(cs, &to);
}
- err = set_cpus_allowed_ptr(tsk, cpus_attach);
- if (err)
- return;

- task_lock(tsk);
- cpuset_change_task_nodemask(tsk, &to);
- task_unlock(tsk);
- cpuset_update_task_spread_flag(cs, tsk);
+ /* do per-task migration stuff possibly for each in the threadgroup */
+ cpuset_attach_task(tsk, &to, cs);
+ if (threadgroup) {
+ struct task_struct *c;
+ rcu_read_lock();
+ list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
+ cpuset_attach_task(c, &to, cs);
+ }
+ rcu_read_unlock();
+ }

+ /* change mm; only needs to be done once even if threadgroup */
from = oldcs->mems_allowed;
to = cs->mems_allowed;
mm = get_task_mm(tsk);
diff --git a/kernel/ns_cgroup.c b/kernel/ns_cgroup.c
index 5aa854f..2a5dfec 100644
--- a/kernel/ns_cgroup.c
+++ b/kernel/ns_cgroup.c
@@ -42,8 +42,8 @@ int ns_cgroup_clone(struct task_struct *task, struct pid *pid)
* (hence either you are in the same cgroup as task, or in an
* ancestor cgroup thereof)
*/
-static int ns_can_attach(struct cgroup_subsys *ss,
- struct cgroup *new_cgroup, struct task_struct *task)
+static int ns_can_attach(struct cgroup_subsys *ss, struct cgroup *new_cgroup,
+ struct task_struct *task, bool threadgroup)
{
if (current != task) {
if (!capable(CAP_SYS_ADMIN))
@@ -56,6 +56,18 @@ static int ns_can_attach(struct cgroup_subsys *ss,
if (!cgroup_is_descendant(new_cgroup, task))
return -EPERM;

+ if (threadgroup) {
+ struct task_struct *c;
+ rcu_read_lock();
+ list_for_each_entry_rcu(c, &task->thread_group, thread_group) {
+ if (!cgroup_is_descendant(new_cgroup, c)) {
+ rcu_read_unlock();
+ return -EPERM;
+ }
+ }
+ rcu_read_unlock();
+ }
+
return 0;
}

diff --git a/kernel/sched.c b/kernel/sched.c
index 3393c18..b5e371b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -10194,8 +10194,7 @@ cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
}

static int
-cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct task_struct *tsk)
+cpu_cgroup_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
{
#ifdef CONFIG_RT_GROUP_SCHED
if (!sched_rt_can_attach(cgroup_tg(cgrp), tsk))
@@ -10209,11 +10208,43 @@ cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
return 0;
}

+static int
+cpu_cgroup_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
+ struct task_struct *tsk, bool threadgroup)
+{
+ int retval = cpu_cgroup_can_attach_task(cgrp, tsk);
+ if (retval)
+ return retval;
+ if (threadgroup) {
+ struct task_struct *c;
+ rcu_read_lock();
+ list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
+ retval = cpu_cgroup_can_attach_task(cgrp, c);
+ if (retval) {
+ rcu_read_unlock();
+ return retval;
+ }
+ }
+ rcu_read_unlock();
+ }
+ return 0;
+
+}
+
static void
cpu_cgroup_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
- struct cgroup *old_cont, struct task_struct *tsk)
+ struct cgroup *old_cont, struct task_struct *tsk
+ bool threadgroup)
{
sched_move_task(tsk);
+ if (threadgroup) {
+ struct task_struct *c;
+ rcu_read_lock();
+ list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) {
+ sched_move_task(c);
+ }
+ rcu_read_unlock();
+ }
}

#ifdef CONFIG_FAIR_GROUP_SCHED
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6ceb6f2..d9e9cf4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2584,7 +2584,8 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss,
static void mem_cgroup_move_task(struct cgroup_subsys *ss,
struct cgroup *cont,
struct cgroup *old_cont,
- struct task_struct *p)
+ struct task_struct *p,
+ bool threadgroup)
{
mutex_lock(&memcg_tasklist);
/*
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index b8186ba..6cf8fd2 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -61,7 +61,8 @@ static inline struct dev_cgroup *task_devcgroup(struct task_struct *task)
struct cgroup_subsys devices_subsys;

static int devcgroup_can_attach(struct cgroup_subsys *ss,
- struct cgroup *new_cgroup, struct task_struct *task)
+ struct cgroup *new_cgroup, struct task_struct *task,
+ bool threadgroup)
{
if (current != task && !capable(CAP_SYS_ADMIN))
return -EPERM;


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