diff options
Diffstat (limited to 'kernel/cgroup')
| -rw-r--r-- | kernel/cgroup/cgroup.c | 51 | ||||
| -rw-r--r-- | kernel/cgroup/namespace.c | 29 |
2 files changed, 53 insertions, 27 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 312c6a8b55bb..a0d5d62f1483 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -59,6 +59,7 @@ #include <linux/sched/cputime.h> #include <linux/sched/deadline.h> #include <linux/psi.h> +#include <linux/nstree.h> #include <net/sock.h> #define CREATE_TRACE_POINTS @@ -126,8 +127,31 @@ DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem); * of concurrent destructions. Use a separate workqueue so that cgroup * destruction work items don't end up filling up max_active of system_wq * which may lead to deadlock. + * + * A cgroup destruction should enqueue work sequentially to: + * cgroup_offline_wq: use for css offline work + * cgroup_release_wq: use for css release work + * cgroup_free_wq: use for free work + * + * Rationale for using separate workqueues: + * The cgroup root free work may depend on completion of other css offline + * operations. If all tasks were enqueued to a single workqueue, this could + * create a deadlock scenario where: + * - Free work waits for other css offline work to complete. + * - But other css offline work is queued after free work in the same queue. + * + * Example deadlock scenario with single workqueue (cgroup_destroy_wq): + * 1. umount net_prio + * 2. net_prio root destruction enqueues work to cgroup_destroy_wq (CPUx) + * 3. perf_event CSS A offline enqueues work to same cgroup_destroy_wq (CPUx) + * 4. net_prio cgroup_destroy_root->cgroup_lock_and_drain_offline. + * 5. net_prio root destruction blocks waiting for perf_event CSS A offline, + * which can never complete as it's behind in the same queue and + * workqueue's max_active is 1. */ -static struct workqueue_struct *cgroup_destroy_wq; +static struct workqueue_struct *cgroup_offline_wq; +static struct workqueue_struct *cgroup_release_wq; +static struct workqueue_struct *cgroup_free_wq; /* generate an array of cgroup subsystem pointers */ #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, @@ -218,11 +242,12 @@ static bool have_favordynmods __ro_after_init = IS_ENABLED(CONFIG_CGROUP_FAVOR_D /* cgroup namespace for init task */ struct cgroup_namespace init_cgroup_ns = { - .ns.count = REFCOUNT_INIT(2), + .ns.__ns_ref = REFCOUNT_INIT(2), .user_ns = &init_user_ns, .ns.ops = &cgroupns_operations, - .ns.inum = PROC_CGROUP_INIT_INO, + .ns.inum = ns_init_inum(&init_cgroup_ns), .root_cset = &init_css_set, + .ns.ns_type = ns_common_type(&init_cgroup_ns), }; static struct file_system_type cgroup2_fs_type; @@ -4159,6 +4184,7 @@ static void cgroup_file_release(struct kernfs_open_file *of) cft->release(of); put_cgroup_ns(ctx->ns); kfree(ctx); + of->priv = NULL; } static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, @@ -5558,7 +5584,7 @@ static void css_release_work_fn(struct work_struct *work) cgroup_unlock(); INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn); - queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork); + queue_rcu_work(cgroup_free_wq, &css->destroy_rwork); } static void css_release(struct percpu_ref *ref) @@ -5567,7 +5593,7 @@ static void css_release(struct percpu_ref *ref) container_of(ref, struct cgroup_subsys_state, refcnt); INIT_WORK(&css->destroy_work, css_release_work_fn); - queue_work(cgroup_destroy_wq, &css->destroy_work); + queue_work(cgroup_release_wq, &css->destroy_work); } static void init_and_link_css(struct cgroup_subsys_state *css, @@ -5701,7 +5727,7 @@ err_list_del: list_del_rcu(&css->sibling); err_free_css: INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn); - queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork); + queue_rcu_work(cgroup_free_wq, &css->destroy_rwork); return ERR_PTR(err); } @@ -5939,7 +5965,7 @@ static void css_killed_ref_fn(struct percpu_ref *ref) if (atomic_dec_and_test(&css->online_cnt)) { INIT_WORK(&css->destroy_work, css_killed_work_fn); - queue_work(cgroup_destroy_wq, &css->destroy_work); + queue_work(cgroup_offline_wq, &css->destroy_work); } } @@ -6312,6 +6338,7 @@ int __init cgroup_init(void) WARN_ON(register_filesystem(&cpuset_fs_type)); #endif + ns_tree_add(&init_cgroup_ns); return 0; } @@ -6325,8 +6352,14 @@ static int __init cgroup_wq_init(void) * We would prefer to do this in cgroup_init() above, but that * is called before init_workqueues(): so leave this until after. */ - cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); - BUG_ON(!cgroup_destroy_wq); + cgroup_offline_wq = alloc_workqueue("cgroup_offline", 0, 1); + BUG_ON(!cgroup_offline_wq); + + cgroup_release_wq = alloc_workqueue("cgroup_release", 0, 1); + BUG_ON(!cgroup_release_wq); + + cgroup_free_wq = alloc_workqueue("cgroup_free", 0, 1); + BUG_ON(!cgroup_free_wq); return 0; } core_initcall(cgroup_wq_init); diff --git a/kernel/cgroup/namespace.c b/kernel/cgroup/namespace.c index 144a464e45c6..fdbe57578e68 100644 --- a/kernel/cgroup/namespace.c +++ b/kernel/cgroup/namespace.c @@ -5,7 +5,7 @@ #include <linux/slab.h> #include <linux/nsproxy.h> #include <linux/proc_ns.h> - +#include <linux/nstree.h> /* cgroup namespaces */ @@ -21,33 +21,32 @@ static void dec_cgroup_namespaces(struct ucounts *ucounts) static struct cgroup_namespace *alloc_cgroup_ns(void) { - struct cgroup_namespace *new_ns; + struct cgroup_namespace *new_ns __free(kfree) = NULL; int ret; new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL_ACCOUNT); if (!new_ns) return ERR_PTR(-ENOMEM); - ret = ns_alloc_inum(&new_ns->ns); - if (ret) { - kfree(new_ns); + ret = ns_common_init(new_ns); + if (ret) return ERR_PTR(ret); - } - refcount_set(&new_ns->ns.count, 1); - new_ns->ns.ops = &cgroupns_operations; - return new_ns; + ns_tree_add(new_ns); + return no_free_ptr(new_ns); } void free_cgroup_ns(struct cgroup_namespace *ns) { + ns_tree_remove(ns); put_css_set(ns->root_cset); dec_cgroup_namespaces(ns->ucounts); put_user_ns(ns->user_ns); - ns_free_inum(&ns->ns); - kfree(ns); + ns_common_free(ns); + /* Concurrent nstree traversal depends on a grace period. */ + kfree_rcu(ns, ns.ns_rcu); } EXPORT_SYMBOL(free_cgroup_ns); -struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, +struct cgroup_namespace *copy_cgroup_ns(u64 flags, struct user_namespace *user_ns, struct cgroup_namespace *old_ns) { @@ -90,11 +89,6 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, return new_ns; } -static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns) -{ - return container_of(ns, struct cgroup_namespace, ns); -} - static int cgroupns_install(struct nsset *nsset, struct ns_common *ns) { struct nsproxy *nsproxy = nsset->nsproxy; @@ -143,7 +137,6 @@ static struct user_namespace *cgroupns_owner(struct ns_common *ns) const struct proc_ns_operations cgroupns_operations = { .name = "cgroup", - .type = CLONE_NEWCGROUP, .get = cgroupns_get, .put = cgroupns_put, .install = cgroupns_install, |