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-rw-r--r--kernel/cgroup/cgroup-internal.h6
-rw-r--r--kernel/cgroup/cgroup-v1.c16
-rw-r--r--kernel/cgroup/cgroup.c148
-rw-r--r--kernel/cgroup/cpuset.c27
4 files changed, 148 insertions, 49 deletions
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index 236f290224aa..803989eae99e 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -169,7 +169,6 @@ extern struct mutex cgroup_mutex;
extern spinlock_t css_set_lock;
extern struct cgroup_subsys *cgroup_subsys[];
extern struct list_head cgroup_roots;
-extern struct file_system_type cgroup_fs_type;
/* iterate across the hierarchies */
#define for_each_root(root) \
@@ -250,9 +249,10 @@ int cgroup_migrate(struct task_struct *leader, bool threadgroup,
int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
bool threadgroup);
-struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)
+struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup,
+ bool *locked)
__acquires(&cgroup_threadgroup_rwsem);
-void cgroup_procs_write_finish(struct task_struct *task)
+void cgroup_procs_write_finish(struct task_struct *task, bool locked)
__releases(&cgroup_threadgroup_rwsem);
void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 117d70098cd4..6fcabeacb7d8 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -15,6 +15,7 @@
#include <linux/pid_namespace.h>
#include <linux/cgroupstats.h>
#include <linux/fs_parser.h>
+#include <linux/cpu.h>
#include <trace/events/cgroup.h>
@@ -62,6 +63,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
int retval = 0;
mutex_lock(&cgroup_mutex);
+ cpus_read_lock();
percpu_down_write(&cgroup_threadgroup_rwsem);
for_each_root(root) {
struct cgroup *from_cgrp;
@@ -78,6 +80,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
break;
}
percpu_up_write(&cgroup_threadgroup_rwsem);
+ cpus_read_unlock();
mutex_unlock(&cgroup_mutex);
return retval;
@@ -364,10 +367,9 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
}
css_task_iter_end(&it);
length = n;
- /* now sort & (if procs) strip out duplicates */
+ /* now sort & strip out duplicates (tgids or recycled thread PIDs) */
sort(array, length, sizeof(pid_t), cmppid, NULL);
- if (type == CGROUP_FILE_PROCS)
- length = pidlist_uniq(array, length);
+ length = pidlist_uniq(array, length);
l = cgroup_pidlist_find_create(cgrp, type);
if (!l) {
@@ -498,12 +500,13 @@ static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
struct task_struct *task;
const struct cred *cred, *tcred;
ssize_t ret;
+ bool locked;
cgrp = cgroup_kn_lock_live(of->kn, false);
if (!cgrp)
return -ENODEV;
- task = cgroup_procs_write_start(buf, threadgroup);
+ task = cgroup_procs_write_start(buf, threadgroup, &locked);
ret = PTR_ERR_OR_ZERO(task);
if (ret)
goto out_unlock;
@@ -526,7 +529,7 @@ static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
ret = cgroup_attach_task(cgrp, task, threadgroup);
out_finish:
- cgroup_procs_write_finish(task);
+ cgroup_procs_write_finish(task, locked);
out_unlock:
cgroup_kn_unlock(of->kn);
@@ -940,6 +943,9 @@ int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
for_each_subsys(ss, i) {
if (strcmp(param->key, ss->legacy_name))
continue;
+ if (!cgroup_ssid_enabled(i) || cgroup1_ssid_disabled(i))
+ return invalf(fc, "Disabled controller '%s'",
+ param->key);
ctx->subsys_mask |= (1 << i);
return 0;
}
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 177d57ce9016..62a7a5075014 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -30,6 +30,7 @@
#include "cgroup-internal.h"
+#include <linux/cpu.h>
#include <linux/cred.h>
#include <linux/errno.h>
#include <linux/init_task.h>
@@ -743,7 +744,8 @@ struct css_set init_css_set = {
.task_iters = LIST_HEAD_INIT(init_css_set.task_iters),
.threaded_csets = LIST_HEAD_INIT(init_css_set.threaded_csets),
.cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
- .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
+ .mg_src_preload_node = LIST_HEAD_INIT(init_css_set.mg_src_preload_node),
+ .mg_dst_preload_node = LIST_HEAD_INIT(init_css_set.mg_dst_preload_node),
.mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
/*
@@ -1219,7 +1221,8 @@ static struct css_set *find_css_set(struct css_set *old_cset,
INIT_LIST_HEAD(&cset->threaded_csets);
INIT_HLIST_NODE(&cset->hlist);
INIT_LIST_HEAD(&cset->cgrp_links);
- INIT_LIST_HEAD(&cset->mg_preload_node);
+ INIT_LIST_HEAD(&cset->mg_src_preload_node);
+ INIT_LIST_HEAD(&cset->mg_dst_preload_node);
INIT_LIST_HEAD(&cset->mg_node);
/* Copy the set of subsystem state objects generated in
@@ -1720,7 +1723,7 @@ int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
{
struct cgroup *dcgrp = &dst_root->cgrp;
struct cgroup_subsys *ss;
- int ssid, i, ret;
+ int ssid, ret;
u16 dfl_disable_ss_mask = 0;
lockdep_assert_held(&cgroup_mutex);
@@ -1764,7 +1767,8 @@ int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
struct cgroup_root *src_root = ss->root;
struct cgroup *scgrp = &src_root->cgrp;
struct cgroup_subsys_state *css = cgroup_css(scgrp, ss);
- struct css_set *cset;
+ struct css_set *cset, *cset_pos;
+ struct css_task_iter *it;
WARN_ON(!css || cgroup_css(dcgrp, ss));
@@ -1782,9 +1786,22 @@ int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
css->cgroup = dcgrp;
spin_lock_irq(&css_set_lock);
- hash_for_each(css_set_table, i, cset, hlist)
+ WARN_ON(!list_empty(&dcgrp->e_csets[ss->id]));
+ list_for_each_entry_safe(cset, cset_pos, &scgrp->e_csets[ss->id],
+ e_cset_node[ss->id]) {
list_move_tail(&cset->e_cset_node[ss->id],
&dcgrp->e_csets[ss->id]);
+ /*
+ * all css_sets of scgrp together in same order to dcgrp,
+ * patch in-flight iterators to preserve correct iteration.
+ * since the iterator is always advanced right away and
+ * finished when it->cset_pos meets it->cset_head, so only
+ * update it->cset_head is enough here.
+ */
+ list_for_each_entry(it, &cset->task_iters, iters_node)
+ if (it->cset_head == &scgrp->e_csets[ss->id])
+ it->cset_head = &dcgrp->e_csets[ss->id];
+ }
spin_unlock_irq(&css_set_lock);
/* default hierarchy doesn't enable controllers by default */
@@ -2375,6 +2392,47 @@ int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
EXPORT_SYMBOL_GPL(task_cgroup_path);
/**
+ * cgroup_attach_lock - Lock for ->attach()
+ * @lock_threadgroup: whether to down_write cgroup_threadgroup_rwsem
+ *
+ * cgroup migration sometimes needs to stabilize threadgroups against forks and
+ * exits by write-locking cgroup_threadgroup_rwsem. However, some ->attach()
+ * implementations (e.g. cpuset), also need to disable CPU hotplug.
+ * Unfortunately, letting ->attach() operations acquire cpus_read_lock() can
+ * lead to deadlocks.
+ *
+ * Bringing up a CPU may involve creating and destroying tasks which requires
+ * read-locking threadgroup_rwsem, so threadgroup_rwsem nests inside
+ * cpus_read_lock(). If we call an ->attach() which acquires the cpus lock while
+ * write-locking threadgroup_rwsem, the locking order is reversed and we end up
+ * waiting for an on-going CPU hotplug operation which in turn is waiting for
+ * the threadgroup_rwsem to be released to create new tasks. For more details:
+ *
+ * http://lkml.kernel.org/r/20220711174629.uehfmqegcwn2lqzu@wubuntu
+ *
+ * Resolve the situation by always acquiring cpus_read_lock() before optionally
+ * write-locking cgroup_threadgroup_rwsem. This allows ->attach() to assume that
+ * CPU hotplug is disabled on entry.
+ */
+static void cgroup_attach_lock(bool lock_threadgroup)
+{
+ cpus_read_lock();
+ if (lock_threadgroup)
+ percpu_down_write(&cgroup_threadgroup_rwsem);
+}
+
+/**
+ * cgroup_attach_unlock - Undo cgroup_attach_lock()
+ * @lock_threadgroup: whether to up_write cgroup_threadgroup_rwsem
+ */
+static void cgroup_attach_unlock(bool lock_threadgroup)
+{
+ if (lock_threadgroup)
+ percpu_up_write(&cgroup_threadgroup_rwsem);
+ cpus_read_unlock();
+}
+
+/**
* cgroup_migrate_add_task - add a migration target task to a migration context
* @task: target task
* @mgctx: target migration context
@@ -2629,21 +2687,27 @@ int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp)
*/
void cgroup_migrate_finish(struct cgroup_mgctx *mgctx)
{
- LIST_HEAD(preloaded);
struct css_set *cset, *tmp_cset;
lockdep_assert_held(&cgroup_mutex);
spin_lock_irq(&css_set_lock);
- list_splice_tail_init(&mgctx->preloaded_src_csets, &preloaded);
- list_splice_tail_init(&mgctx->preloaded_dst_csets, &preloaded);
+ list_for_each_entry_safe(cset, tmp_cset, &mgctx->preloaded_src_csets,
+ mg_src_preload_node) {
+ cset->mg_src_cgrp = NULL;
+ cset->mg_dst_cgrp = NULL;
+ cset->mg_dst_cset = NULL;
+ list_del_init(&cset->mg_src_preload_node);
+ put_css_set_locked(cset);
+ }
- list_for_each_entry_safe(cset, tmp_cset, &preloaded, mg_preload_node) {
+ list_for_each_entry_safe(cset, tmp_cset, &mgctx->preloaded_dst_csets,
+ mg_dst_preload_node) {
cset->mg_src_cgrp = NULL;
cset->mg_dst_cgrp = NULL;
cset->mg_dst_cset = NULL;
- list_del_init(&cset->mg_preload_node);
+ list_del_init(&cset->mg_dst_preload_node);
put_css_set_locked(cset);
}
@@ -2685,7 +2749,7 @@ void cgroup_migrate_add_src(struct css_set *src_cset,
src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
- if (!list_empty(&src_cset->mg_preload_node))
+ if (!list_empty(&src_cset->mg_src_preload_node))
return;
WARN_ON(src_cset->mg_src_cgrp);
@@ -2696,7 +2760,7 @@ void cgroup_migrate_add_src(struct css_set *src_cset,
src_cset->mg_src_cgrp = src_cgrp;
src_cset->mg_dst_cgrp = dst_cgrp;
get_css_set(src_cset);
- list_add_tail(&src_cset->mg_preload_node, &mgctx->preloaded_src_csets);
+ list_add_tail(&src_cset->mg_src_preload_node, &mgctx->preloaded_src_csets);
}
/**
@@ -2721,7 +2785,7 @@ int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx)
/* look up the dst cset for each src cset and link it to src */
list_for_each_entry_safe(src_cset, tmp_cset, &mgctx->preloaded_src_csets,
- mg_preload_node) {
+ mg_src_preload_node) {
struct css_set *dst_cset;
struct cgroup_subsys *ss;
int ssid;
@@ -2740,7 +2804,7 @@ int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx)
if (src_cset == dst_cset) {
src_cset->mg_src_cgrp = NULL;
src_cset->mg_dst_cgrp = NULL;
- list_del_init(&src_cset->mg_preload_node);
+ list_del_init(&src_cset->mg_src_preload_node);
put_css_set(src_cset);
put_css_set(dst_cset);
continue;
@@ -2748,8 +2812,8 @@ int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx)
src_cset->mg_dst_cset = dst_cset;
- if (list_empty(&dst_cset->mg_preload_node))
- list_add_tail(&dst_cset->mg_preload_node,
+ if (list_empty(&dst_cset->mg_dst_preload_node))
+ list_add_tail(&dst_cset->mg_dst_preload_node,
&mgctx->preloaded_dst_csets);
else
put_css_set(dst_cset);
@@ -2848,8 +2912,8 @@ int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
return ret;
}
-struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)
- __acquires(&cgroup_threadgroup_rwsem)
+struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup,
+ bool *threadgroup_locked)
{
struct task_struct *tsk;
pid_t pid;
@@ -2857,7 +2921,17 @@ struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)
if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
return ERR_PTR(-EINVAL);
- percpu_down_write(&cgroup_threadgroup_rwsem);
+ /*
+ * If we migrate a single thread, we don't care about threadgroup
+ * stability. If the thread is `current`, it won't exit(2) under our
+ * hands or change PID through exec(2). We exclude
+ * cgroup_update_dfl_csses and other cgroup_{proc,thread}s_write
+ * callers by cgroup_mutex.
+ * Therefore, we can skip the global lock.
+ */
+ lockdep_assert_held(&cgroup_mutex);
+ *threadgroup_locked = pid || threadgroup;
+ cgroup_attach_lock(*threadgroup_locked);
rcu_read_lock();
if (pid) {
@@ -2888,14 +2962,14 @@ struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)
goto out_unlock_rcu;
out_unlock_threadgroup:
- percpu_up_write(&cgroup_threadgroup_rwsem);
+ cgroup_attach_unlock(*threadgroup_locked);
+ *threadgroup_locked = false;
out_unlock_rcu:
rcu_read_unlock();
return tsk;
}
-void cgroup_procs_write_finish(struct task_struct *task)
- __releases(&cgroup_threadgroup_rwsem)
+void cgroup_procs_write_finish(struct task_struct *task, bool threadgroup_locked)
{
struct cgroup_subsys *ss;
int ssid;
@@ -2903,7 +2977,8 @@ void cgroup_procs_write_finish(struct task_struct *task)
/* release reference from cgroup_procs_write_start() */
put_task_struct(task);
- percpu_up_write(&cgroup_threadgroup_rwsem);
+ cgroup_attach_unlock(threadgroup_locked);
+
for_each_subsys(ss, ssid)
if (ss->post_attach)
ss->post_attach();
@@ -2958,12 +3033,11 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp)
struct cgroup_subsys_state *d_css;
struct cgroup *dsct;
struct css_set *src_cset;
+ bool has_tasks;
int ret;
lockdep_assert_held(&cgroup_mutex);
- percpu_down_write(&cgroup_threadgroup_rwsem);
-
/* look up all csses currently attached to @cgrp's subtree */
spin_lock_irq(&css_set_lock);
cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
@@ -2974,13 +3048,23 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp)
}
spin_unlock_irq(&css_set_lock);
+ /*
+ * We need to write-lock threadgroup_rwsem while migrating tasks.
+ * However, if there are no source csets for @cgrp, changing its
+ * controllers isn't gonna produce any task migrations and the
+ * write-locking can be skipped safely.
+ */
+ has_tasks = !list_empty(&mgctx.preloaded_src_csets);
+ cgroup_attach_lock(has_tasks);
+
/* NULL dst indicates self on default hierarchy */
ret = cgroup_migrate_prepare_dst(&mgctx);
if (ret)
goto out_finish;
spin_lock_irq(&css_set_lock);
- list_for_each_entry(src_cset, &mgctx.preloaded_src_csets, mg_preload_node) {
+ list_for_each_entry(src_cset, &mgctx.preloaded_src_csets,
+ mg_src_preload_node) {
struct task_struct *task, *ntask;
/* all tasks in src_csets need to be migrated */
@@ -2992,7 +3076,7 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp)
ret = cgroup_migrate_execute(&mgctx);
out_finish:
cgroup_migrate_finish(&mgctx);
- percpu_up_write(&cgroup_threadgroup_rwsem);
+ cgroup_attach_unlock(has_tasks);
return ret;
}
@@ -4821,12 +4905,13 @@ static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
struct task_struct *task;
const struct cred *saved_cred;
ssize_t ret;
+ bool threadgroup_locked;
dst_cgrp = cgroup_kn_lock_live(of->kn, false);
if (!dst_cgrp)
return -ENODEV;
- task = cgroup_procs_write_start(buf, true);
+ task = cgroup_procs_write_start(buf, true, &threadgroup_locked);
ret = PTR_ERR_OR_ZERO(task);
if (ret)
goto out_unlock;
@@ -4852,7 +4937,7 @@ static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
ret = cgroup_attach_task(dst_cgrp, task, true);
out_finish:
- cgroup_procs_write_finish(task);
+ cgroup_procs_write_finish(task, threadgroup_locked);
out_unlock:
cgroup_kn_unlock(of->kn);
@@ -4872,6 +4957,7 @@ static ssize_t cgroup_threads_write(struct kernfs_open_file *of,
struct task_struct *task;
const struct cred *saved_cred;
ssize_t ret;
+ bool locked;
buf = strstrip(buf);
@@ -4879,7 +4965,7 @@ static ssize_t cgroup_threads_write(struct kernfs_open_file *of,
if (!dst_cgrp)
return -ENODEV;
- task = cgroup_procs_write_start(buf, false);
+ task = cgroup_procs_write_start(buf, false, &locked);
ret = PTR_ERR_OR_ZERO(task);
if (ret)
goto out_unlock;
@@ -4910,7 +4996,7 @@ static ssize_t cgroup_threads_write(struct kernfs_open_file *of,
ret = cgroup_attach_task(dst_cgrp, task, false);
out_finish:
- cgroup_procs_write_finish(task);
+ cgroup_procs_write_finish(task, locked);
out_unlock:
cgroup_kn_unlock(of->kn);
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index b02eca235ba3..5d50ac2f2652 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -33,6 +33,7 @@
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
+#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/mempolicy.h>
#include <linux/mm.h>
@@ -1057,10 +1058,18 @@ static void update_tasks_cpumask(struct cpuset *cs)
{
struct css_task_iter it;
struct task_struct *task;
+ bool top_cs = cs == &top_cpuset;
css_task_iter_start(&cs->css, 0, &it);
- while ((task = css_task_iter_next(&it)))
+ while ((task = css_task_iter_next(&it))) {
+ /*
+ * Percpu kthreads in top_cpuset are ignored
+ */
+ if (top_cs && (task->flags & PF_KTHREAD) &&
+ kthread_is_per_cpu(task))
+ continue;
set_cpus_allowed_ptr(task, cs->effective_cpus);
+ }
css_task_iter_end(&it);
}
@@ -2014,12 +2023,7 @@ static int update_prstate(struct cpuset *cs, int val)
update_flag(CS_CPU_EXCLUSIVE, cs, 0);
}
- /*
- * Update cpumask of parent's tasks except when it is the top
- * cpuset as some system daemons cannot be mapped to other CPUs.
- */
- if (parent != &top_cpuset)
- update_tasks_cpumask(parent);
+ update_tasks_cpumask(parent);
if (parent->child_ecpus_count)
update_sibling_cpumasks(parent, cs, &tmp);
@@ -2176,11 +2180,15 @@ out_unlock:
static void cpuset_cancel_attach(struct cgroup_taskset *tset)
{
struct cgroup_subsys_state *css;
+ struct cpuset *cs;
cgroup_taskset_first(tset, &css);
+ cs = css_cs(css);
percpu_down_write(&cpuset_rwsem);
- css_cs(css)->attach_in_progress--;
+ cs->attach_in_progress--;
+ if (!cs->attach_in_progress)
+ wake_up(&cpuset_attach_wq);
percpu_up_write(&cpuset_rwsem);
}
@@ -2204,7 +2212,7 @@ static void cpuset_attach(struct cgroup_taskset *tset)
cgroup_taskset_first(tset, &css);
cs = css_cs(css);
- cpus_read_lock();
+ lockdep_assert_cpus_held(); /* see cgroup_attach_lock() */
percpu_down_write(&cpuset_rwsem);
/* prepare for attach */
@@ -2260,7 +2268,6 @@ static void cpuset_attach(struct cgroup_taskset *tset)
wake_up(&cpuset_attach_wq);
percpu_up_write(&cpuset_rwsem);
- cpus_read_unlock();
}
/* The various types of files and directories in a cpuset file system */
generated by cgit 1.2.3-korg (git 2.39.0) at 2024-05-16 02:44:51 +0000