diff options
Diffstat (limited to 'kernel/cgroup')
| -rw-r--r-- | kernel/cgroup/cgroup-internal.h | 1 | ||||
| -rw-r--r-- | kernel/cgroup/cgroup-v1.c | 8 | ||||
| -rw-r--r-- | kernel/cgroup/cgroup.c | 70 | ||||
| -rw-r--r-- | kernel/cgroup/cpuset.c | 29 | ||||
| -rw-r--r-- | kernel/cgroup/namespace.c | 6 |
5 files changed, 85 insertions, 29 deletions
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h index 8f7729b0a638..4168e7d97e87 100644 --- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -148,7 +148,6 @@ 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) \ diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index 61644976225a..55a61deb3d04 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -13,6 +13,7 @@ #include <linux/delayacct.h> #include <linux/pid_namespace.h> #include <linux/cgroupstats.h> +#include <linux/cpu.h> #include <trace/events/cgroup.h> @@ -55,6 +56,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) int retval = 0; mutex_lock(&cgroup_mutex); + get_online_cpus(); percpu_down_write(&cgroup_threadgroup_rwsem); for_each_root(root) { struct cgroup *from_cgrp; @@ -71,6 +73,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) break; } percpu_up_write(&cgroup_threadgroup_rwsem); + put_online_cpus(); mutex_unlock(&cgroup_mutex); return retval; @@ -392,10 +395,9 @@ 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) { diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index a892a99eb4bf..6322b56529e9 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -55,6 +55,7 @@ #include <linux/nsproxy.h> #include <linux/file.h> #include <linux/sched/cputime.h> +#include <linux/cpu.h> #include <net/sock.h> #define CREATE_TRACE_POINTS @@ -1651,7 +1652,7 @@ 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); @@ -1695,7 +1696,8 @@ 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)); @@ -1713,9 +1715,22 @@ 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 */ @@ -2210,6 +2225,45 @@ 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(void) +{ + get_online_cpus(); + 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(void) +{ + percpu_up_write(&cgroup_threadgroup_rwsem); + put_online_cpus(); +} + +/** * cgroup_migrate_add_task - add a migration target task to a migration context * @task: target task * @mgctx: target migration context @@ -2694,7 +2748,7 @@ 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); + cgroup_attach_lock(); rcu_read_lock(); if (pid) { @@ -2725,7 +2779,7 @@ 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(); out_unlock_rcu: rcu_read_unlock(); return tsk; @@ -2740,7 +2794,7 @@ 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(); for_each_subsys(ss, ssid) if (ss->post_attach) ss->post_attach(); @@ -2799,7 +2853,7 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp) lockdep_assert_held(&cgroup_mutex); - percpu_down_write(&cgroup_threadgroup_rwsem); + cgroup_attach_lock(); /* look up all csses currently attached to @cgrp's subtree */ spin_lock_irq(&css_set_lock); @@ -2830,7 +2884,7 @@ 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(); return ret; } diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index dcd5755b1fe2..3067d3e5a51d 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -830,8 +830,8 @@ static void rebuild_sched_domains_locked(void) cpumask_var_t *doms; int ndoms; + lockdep_assert_cpus_held(); lockdep_assert_held(&cpuset_mutex); - get_online_cpus(); /* * We have raced with CPU hotplug. Don't do anything to avoid @@ -839,15 +839,13 @@ static void rebuild_sched_domains_locked(void) * Anyways, hotplug work item will rebuild sched domains. */ if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) - goto out; + return; /* Generate domain masks and attrs */ ndoms = generate_sched_domains(&doms, &attr); /* Have scheduler rebuild the domains */ partition_sched_domains(ndoms, doms, attr); -out: - put_online_cpus(); } #else /* !CONFIG_SMP */ static void rebuild_sched_domains_locked(void) @@ -857,9 +855,11 @@ static void rebuild_sched_domains_locked(void) void rebuild_sched_domains(void) { + get_online_cpus(); mutex_lock(&cpuset_mutex); rebuild_sched_domains_locked(); mutex_unlock(&cpuset_mutex); + put_online_cpus(); } /** @@ -1504,7 +1504,9 @@ static void cpuset_cancel_attach(struct cgroup_taskset *tset) cs = css_cs(css); mutex_lock(&cpuset_mutex); - css_cs(css)->attach_in_progress--; + cs->attach_in_progress--; + if (!cs->attach_in_progress) + wake_up(&cpuset_attach_wq); mutex_unlock(&cpuset_mutex); } @@ -1528,13 +1530,9 @@ static void cpuset_attach(struct cgroup_taskset *tset) cgroup_taskset_first(tset, &css); cs = css_cs(css); + lockdep_assert_cpus_held(); /* see cgroup_attach_lock() */ mutex_lock(&cpuset_mutex); - /* - * It should hold cpus lock because a cpu offline event can - * cause set_cpus_allowed_ptr() failed. - */ - get_online_cpus(); /* prepare for attach */ if (cs == &top_cpuset) cpumask_copy(cpus_attach, cpu_possible_mask); @@ -1553,7 +1551,6 @@ static void cpuset_attach(struct cgroup_taskset *tset) cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to); cpuset_update_task_spread_flag(cs, task); } - put_online_cpus(); /* * Change mm for all threadgroup leaders. This is expensive and may @@ -1617,6 +1614,7 @@ static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft, cpuset_filetype_t type = cft->private; int retval = 0; + get_online_cpus(); mutex_lock(&cpuset_mutex); if (!is_cpuset_online(cs)) { retval = -ENODEV; @@ -1654,6 +1652,7 @@ static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft, } out_unlock: mutex_unlock(&cpuset_mutex); + put_online_cpus(); return retval; } @@ -1664,6 +1663,7 @@ static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft, cpuset_filetype_t type = cft->private; int retval = -ENODEV; + get_online_cpus(); mutex_lock(&cpuset_mutex); if (!is_cpuset_online(cs)) goto out_unlock; @@ -1678,6 +1678,7 @@ static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft, } out_unlock: mutex_unlock(&cpuset_mutex); + put_online_cpus(); return retval; } @@ -1716,6 +1717,7 @@ static ssize_t cpuset_write_resmask(struct kernfs_open_file *of, kernfs_break_active_protection(of->kn); flush_work(&cpuset_hotplug_work); + get_online_cpus(); mutex_lock(&cpuset_mutex); if (!is_cpuset_online(cs)) goto out_unlock; @@ -1741,6 +1743,7 @@ static ssize_t cpuset_write_resmask(struct kernfs_open_file *of, free_trial_cpuset(trialcs); out_unlock: mutex_unlock(&cpuset_mutex); + put_online_cpus(); kernfs_unbreak_active_protection(of->kn); css_put(&cs->css); flush_workqueue(cpuset_migrate_mm_wq); @@ -1985,6 +1988,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css) if (!parent) return 0; + get_online_cpus(); mutex_lock(&cpuset_mutex); set_bit(CS_ONLINE, &cs->flags); @@ -2035,6 +2039,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css) spin_unlock_irq(&callback_lock); out_unlock: mutex_unlock(&cpuset_mutex); + put_online_cpus(); return 0; } @@ -2048,6 +2053,7 @@ static void cpuset_css_offline(struct cgroup_subsys_state *css) { struct cpuset *cs = css_cs(css); + get_online_cpus(); mutex_lock(&cpuset_mutex); if (is_sched_load_balance(cs)) @@ -2057,6 +2063,7 @@ static void cpuset_css_offline(struct cgroup_subsys_state *css) clear_bit(CS_ONLINE, &cs->flags); mutex_unlock(&cpuset_mutex); + put_online_cpus(); } static void cpuset_css_free(struct cgroup_subsys_state *css) diff --git a/kernel/cgroup/namespace.c b/kernel/cgroup/namespace.c index b05f1dd58a62..313e66b8c662 100644 --- a/kernel/cgroup/namespace.c +++ b/kernel/cgroup/namespace.c @@ -148,9 +148,3 @@ const struct proc_ns_operations cgroupns_operations = { .install = cgroupns_install, .owner = cgroupns_owner, }; - -static __init int cgroup_namespaces_init(void) -{ - return 0; -} -subsys_initcall(cgroup_namespaces_init); |