diff options
Diffstat (limited to 'kernel/cgroup/cpuset.c')
| -rw-r--r-- | kernel/cgroup/cpuset.c | 1179 |
1 files changed, 793 insertions, 386 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 58f5073acff7..b474289c15b8 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> @@ -69,6 +70,13 @@ DEFINE_STATIC_KEY_FALSE(cpusets_pre_enable_key); DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key); +/* + * There could be abnormal cpuset configurations for cpu or memory + * node binding, add this key to provide a quick low-cost judgment + * of the situation. + */ +DEFINE_STATIC_KEY_FALSE(cpusets_insane_config_key); + /* See "Frequency meter" comments, below. */ struct fmeter { @@ -78,6 +86,30 @@ struct fmeter { spinlock_t lock; /* guards read or write of above */ }; +/* + * Invalid partition error code + */ +enum prs_errcode { + PERR_NONE = 0, + PERR_INVCPUS, + PERR_INVPARENT, + PERR_NOTPART, + PERR_NOTEXCL, + PERR_NOCPUS, + PERR_HOTPLUG, + PERR_CPUSEMPTY, +}; + +static const char * const perr_strings[] = { + [PERR_INVCPUS] = "Invalid cpu list in cpuset.cpus", + [PERR_INVPARENT] = "Parent is an invalid partition root", + [PERR_NOTPART] = "Parent is not a partition root", + [PERR_NOTEXCL] = "Cpu list in cpuset.cpus not exclusive", + [PERR_NOCPUS] = "Parent unable to distribute cpu downstream", + [PERR_HOTPLUG] = "No cpu available due to hotplug", + [PERR_CPUSEMPTY] = "cpuset.cpus is empty", +}; + struct cpuset { struct cgroup_subsys_state css; @@ -98,7 +130,7 @@ struct cpuset { * and if it ends up empty, it will inherit the parent's mask. * * - * On legacy hierachy: + * On legacy hierarchy: * * The user-configured masks are always the same with effective masks. */ @@ -160,25 +192,33 @@ struct cpuset { */ int use_parent_ecpus; int child_ecpus_count; + + /* Invalid partition error code, not lock protected */ + enum prs_errcode prs_err; + + /* Handle for cpuset.cpus.partition */ + struct cgroup_file partition_file; }; /* * Partition root states: * - * 0 - not a partition root - * + * 0 - member (not a partition root) * 1 - partition root - * + * 2 - partition root without load balancing (isolated) * -1 - invalid partition root - * None of the cpus in cpus_allowed can be put into the parent's - * subparts_cpus. In this case, the cpuset is not a real partition - * root anymore. However, the CPU_EXCLUSIVE bit will still be set - * and the cpuset can be restored back to a partition root if the - * parent cpuset can give more CPUs back to this child cpuset. + * -2 - invalid isolated partition root */ -#define PRS_DISABLED 0 -#define PRS_ENABLED 1 -#define PRS_ERROR -1 +#define PRS_MEMBER 0 +#define PRS_ROOT 1 +#define PRS_ISOLATED 2 +#define PRS_INVALID_ROOT -1 +#define PRS_INVALID_ISOLATED -2 + +static inline bool is_prs_invalid(int prs_state) +{ + return prs_state < 0; +} /* * Temporary cpumasks for working with partitions that are passed among @@ -258,15 +298,43 @@ static inline int is_spread_slab(const struct cpuset *cs) return test_bit(CS_SPREAD_SLAB, &cs->flags); } -static inline int is_partition_root(const struct cpuset *cs) +static inline int is_partition_valid(const struct cpuset *cs) { return cs->partition_root_state > 0; } +static inline int is_partition_invalid(const struct cpuset *cs) +{ + return cs->partition_root_state < 0; +} + +/* + * Callers should hold callback_lock to modify partition_root_state. + */ +static inline void make_partition_invalid(struct cpuset *cs) +{ + if (is_partition_valid(cs)) + cs->partition_root_state = -cs->partition_root_state; +} + +/* + * Send notification event of whenever partition_root_state changes. + */ +static inline void notify_partition_change(struct cpuset *cs, int old_prs) +{ + if (old_prs == cs->partition_root_state) + return; + cgroup_file_notify(&cs->partition_file); + + /* Reset prs_err if not invalid */ + if (is_partition_valid(cs)) + WRITE_ONCE(cs->prs_err, PERR_NONE); +} + static struct cpuset top_cpuset = { .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)), - .partition_root_state = PRS_ENABLED, + .partition_root_state = PRS_ROOT, }; /** @@ -298,17 +366,19 @@ static struct cpuset top_cpuset = { if (is_cpuset_online(((des_cs) = css_cs((pos_css))))) /* - * There are two global locks guarding cpuset structures - cpuset_mutex and + * There are two global locks guarding cpuset structures - cpuset_rwsem and * callback_lock. We also require taking task_lock() when dereferencing a * task's cpuset pointer. See "The task_lock() exception", at the end of this - * comment. + * comment. The cpuset code uses only cpuset_rwsem write lock. Other + * kernel subsystems can use cpuset_read_lock()/cpuset_read_unlock() to + * prevent change to cpuset structures. * * A task must hold both locks to modify cpusets. If a task holds - * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it + * cpuset_rwsem, it blocks others wanting that rwsem, ensuring that it * is the only task able to also acquire callback_lock and be able to * modify cpusets. It can perform various checks on the cpuset structure * first, knowing nothing will change. It can also allocate memory while - * just holding cpuset_mutex. While it is performing these checks, various + * just holding cpuset_rwsem. While it is performing these checks, various * callback routines can briefly acquire callback_lock to query cpusets. * Once it is ready to make the changes, it takes callback_lock, blocking * everyone else. @@ -357,9 +427,24 @@ static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn); static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq); +static inline void check_insane_mems_config(nodemask_t *nodes) +{ + if (!cpusets_insane_config() && + movable_only_nodes(nodes)) { + static_branch_enable(&cpusets_insane_config_key); + pr_info("Unsupported (movable nodes only) cpuset configuration detected (nmask=%*pbl)!\n" + "Cpuset allocations might fail even with a lot of memory available.\n", + nodemask_pr_args(nodes)); + } +} + /* - * Cgroup v2 behavior is used when on default hierarchy or the - * cgroup_v2_mode flag is set. + * Cgroup v2 behavior is used on the "cpus" and "mems" control files when + * on default hierarchy or when the cpuset_v2_mode flag is set by mounting + * the v1 cpuset cgroup filesystem with the "cpuset_v2_mode" mount option. + * With v2 behavior, "cpus" and "mems" are always what the users have + * requested and won't be changed by hotplug events. Only the effective + * cpus or mems will be affected. */ static inline bool is_in_v2_mode(void) { @@ -367,33 +452,81 @@ static inline bool is_in_v2_mode(void) (cpuset_cgrp_subsys.root->flags & CGRP_ROOT_CPUSET_V2_MODE); } +/** + * partition_is_populated - check if partition has tasks + * @cs: partition root to be checked + * @excluded_child: a child cpuset to be excluded in task checking + * Return: true if there are tasks, false otherwise + * + * It is assumed that @cs is a valid partition root. @excluded_child should + * be non-NULL when this cpuset is going to become a partition itself. + */ +static inline bool partition_is_populated(struct cpuset *cs, + struct cpuset *excluded_child) +{ + struct cgroup_subsys_state *css; + struct cpuset *child; + + if (cs->css.cgroup->nr_populated_csets) + return true; + if (!excluded_child && !cs->nr_subparts_cpus) + return cgroup_is_populated(cs->css.cgroup); + + rcu_read_lock(); + cpuset_for_each_child(child, css, cs) { + if (child == excluded_child) + continue; + if (is_partition_valid(child)) + continue; + if (cgroup_is_populated(child->css.cgroup)) { + rcu_read_unlock(); + return true; + } + } + rcu_read_unlock(); + return false; +} + /* - * Return in pmask the portion of a cpusets's cpus_allowed that - * are online. If none are online, walk up the cpuset hierarchy - * until we find one that does have some online cpus. + * Return in pmask the portion of a task's cpusets's cpus_allowed that + * are online and are capable of running the task. If none are found, + * walk up the cpuset hierarchy until we find one that does have some + * appropriate cpus. * * One way or another, we guarantee to return some non-empty subset * of cpu_online_mask. * - * Call with callback_lock or cpuset_mutex held. + * Call with callback_lock or cpuset_rwsem held. */ -static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask) +static void guarantee_online_cpus(struct task_struct *tsk, + struct cpumask *pmask) { - while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) { + const struct cpumask *possible_mask = task_cpu_possible_mask(tsk); + struct cpuset *cs; + + if (WARN_ON(!cpumask_and(pmask, possible_mask, cpu_online_mask))) + cpumask_copy(pmask, cpu_online_mask); + + rcu_read_lock(); + cs = task_cs(tsk); + + while (!cpumask_intersects(cs->effective_cpus, pmask)) { cs = parent_cs(cs); if (unlikely(!cs)) { /* * The top cpuset doesn't have any online cpu as a * consequence of a race between cpuset_hotplug_work * and cpu hotplug notifier. But we know the top - * cpuset's effective_cpus is on its way to to be + * cpuset's effective_cpus is on its way to be * identical to cpu_online_mask. */ - cpumask_copy(pmask, cpu_online_mask); - return; + goto out_unlock; } } - cpumask_and(pmask, cs->effective_cpus, cpu_online_mask); + cpumask_and(pmask, pmask, cs->effective_cpus); + +out_unlock: + rcu_read_unlock(); } /* @@ -405,7 +538,7 @@ static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask) * One way or another, we guarantee to return some non-empty subset * of node_states[N_MEMORY]. * - * Call with callback_lock or cpuset_mutex held. + * Call with callback_lock or cpuset_rwsem held. */ static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask) { @@ -417,7 +550,7 @@ static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask) /* * update task's spread flag if cpuset's page/slab spread flag is set * - * Call with callback_lock or cpuset_mutex held. + * Call with callback_lock or cpuset_rwsem held. */ static void cpuset_update_task_spread_flag(struct cpuset *cs, struct task_struct *tsk) @@ -438,7 +571,7 @@ static void cpuset_update_task_spread_flag(struct cpuset *cs, * * One cpuset is a subset of another if all its allowed CPUs and * Memory Nodes are a subset of the other, and its exclusive flags - * are only set if the other's are set. Call holding cpuset_mutex. + * are only set if the other's are set. Call holding cpuset_rwsem. */ static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q) @@ -541,13 +674,42 @@ static inline void free_cpuset(struct cpuset *cs) } /* + * validate_change_legacy() - Validate conditions specific to legacy (v1) + * behavior. + */ +static int validate_change_legacy(struct cpuset *cur, struct cpuset *trial) +{ + struct cgroup_subsys_state *css; + struct cpuset *c, *par; + int ret; + + WARN_ON_ONCE(!rcu_read_lock_held()); + + /* Each of our child cpusets must be a subset of us */ + ret = -EBUSY; + cpuset_for_each_child(c, css, cur) + if (!is_cpuset_subset(c, trial)) + goto out; + + /* On legacy hierarchy, we must be a subset of our parent cpuset. */ + ret = -EACCES; + par = parent_cs(cur); + if (par && !is_cpuset_subset(trial, par)) + goto out; + + ret = 0; +out: + return ret; +} + +/* * validate_change() - Used to validate that any proposed cpuset change * follows the structural rules for cpusets. * * If we replaced the flag and mask values of the current cpuset * (cur) with those values in the trial cpuset (trial), would * our various subset and exclusive rules still be valid? Presumes - * cpuset_mutex held. + * cpuset_rwsem held. * * 'cur' is the address of an actual, in-use cpuset. Operations * such as list traversal that depend on the actual address of the @@ -564,44 +726,21 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial) { struct cgroup_subsys_state *css; struct cpuset *c, *par; - int ret; + int ret = 0; rcu_read_lock(); - /* Each of our child cpusets must be a subset of us */ - ret = -EBUSY; - cpuset_for_each_child(c, css, cur) - if (!is_cpuset_subset(c, trial)) - goto out; + if (!is_in_v2_mode()) + ret = validate_change_legacy(cur, trial); + if (ret) + goto out; /* Remaining checks don't apply to root cpuset */ - ret = 0; if (cur == &top_cpuset) goto out; par = parent_cs(cur); - /* On legacy hiearchy, we must be a subset of our parent cpuset. */ - ret = -EACCES; - if (!is_in_v2_mode() && !is_cpuset_subset(trial, par)) - goto out; - - /* - * If either I or some sibling (!= me) is exclusive, we can't - * overlap - */ - ret = -EINVAL; - cpuset_for_each_child(c, css, par) { - if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) && - c != cur && - cpumask_intersects(trial->cpus_allowed, c->cpus_allowed)) - goto out; - if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) && - c != cur && - nodes_intersects(trial->mems_allowed, c->mems_allowed)) - goto out; - } - /* * Cpusets with tasks - existing or newly being attached - can't * be changed to have empty cpus_allowed or mems_allowed. @@ -626,6 +765,22 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial) trial->cpus_allowed)) goto out; + /* + * If either I or some sibling (!= me) is exclusive, we can't + * overlap + */ + ret = -EINVAL; + cpuset_for_each_child(c, css, par) { + if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) && + c != cur && + cpumask_intersects(trial->cpus_allowed, c->cpus_allowed)) + goto out; + if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) && + c != cur && + nodes_intersects(trial->mems_allowed, c->mems_allowed)) + goto out; + } + ret = 0; out: rcu_read_unlock(); @@ -670,7 +825,7 @@ static void update_domain_attr_tree(struct sched_domain_attr *dattr, rcu_read_unlock(); } -/* Must be called with cpuset_mutex held. */ +/* Must be called with cpuset_rwsem held. */ static inline int nr_cpusets(void) { /* jump label reference count + the top-level cpuset */ @@ -696,7 +851,7 @@ static inline int nr_cpusets(void) * domains when operating in the severe memory shortage situations * that could cause allocation failures below. * - * Must be called with cpuset_mutex held. + * Must be called with cpuset_rwsem held. * * The three key local variables below are: * cp - cpuset pointer, used (together with pos_css) to perform a @@ -761,7 +916,7 @@ static int generate_sched_domains(cpumask_var_t **domains, update_domain_attr_tree(dattr, &top_cpuset); } cpumask_and(doms[0], top_cpuset.effective_cpus, - housekeeping_cpumask(HK_FLAG_DOMAIN)); + housekeeping_cpumask(HK_TYPE_DOMAIN)); goto done; } @@ -791,7 +946,7 @@ static int generate_sched_domains(cpumask_var_t **domains, if (!cpumask_empty(cp->cpus_allowed) && !(is_sched_load_balance(cp) && cpumask_intersects(cp->cpus_allowed, - housekeeping_cpumask(HK_FLAG_DOMAIN)))) + housekeeping_cpumask(HK_TYPE_DOMAIN)))) continue; if (root_load_balance && @@ -803,7 +958,7 @@ static int generate_sched_domains(cpumask_var_t **domains, csa[csn++] = cp; /* skip @cp's subtree if not a partition root */ - if (!is_partition_root(cp)) + if (!is_partition_valid(cp)) pos_css = css_rightmost_descendant(pos_css); } rcu_read_unlock(); @@ -880,7 +1035,7 @@ restart: if (apn == b->pn) { cpumask_or(dp, dp, b->effective_cpus); - cpumask_and(dp, dp, housekeeping_cpumask(HK_FLAG_DOMAIN)); + cpumask_and(dp, dp, housekeeping_cpumask(HK_TYPE_DOMAIN)); if (dattr) update_domain_attr_tree(dattr + nslot, b); @@ -975,29 +1130,52 @@ partition_and_rebuild_sched_domains(int ndoms_new, cpumask_var_t doms_new[], * 'cpus' is removed, then call this routine to rebuild the * scheduler's dynamic sched domains. * - * Call with cpuset_mutex held. Takes get_online_cpus(). + * Call with cpuset_rwsem held. Takes cpus_read_lock(). */ static void rebuild_sched_domains_locked(void) { + struct cgroup_subsys_state *pos_css; struct sched_domain_attr *attr; cpumask_var_t *doms; + struct cpuset *cs; int ndoms; lockdep_assert_cpus_held(); percpu_rwsem_assert_held(&cpuset_rwsem); /* - * We have raced with CPU hotplug. Don't do anything to avoid + * If we have raced with CPU hotplug, return early to avoid * passing doms with offlined cpu to partition_sched_domains(). - * Anyways, hotplug work item will rebuild sched domains. + * Anyways, cpuset_hotplug_workfn() will rebuild sched domains. + * + * With no CPUs in any subpartitions, top_cpuset's effective CPUs + * should be the same as the active CPUs, so checking only top_cpuset + * is enough to detect racing CPU offlines. */ if (!top_cpuset.nr_subparts_cpus && !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) return; - if (top_cpuset.nr_subparts_cpus && - !cpumask_subset(top_cpuset.effective_cpus, cpu_active_mask)) - return; + /* + * With subpartition CPUs, however, the effective CPUs of a partition + * root should be only a subset of the active CPUs. Since a CPU in any + * partition root could be offlined, all must be checked. + */ + if (top_cpuset.nr_subparts_cpus) { + rcu_read_lock(); + cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) { + if (!is_partition_valid(cs)) { + pos_css = css_rightmost_descendant(pos_css); + continue; + } + if (!cpumask_subset(cs->effective_cpus, + cpu_active_mask)) { + rcu_read_unlock(); + return; + } + } + rcu_read_unlock(); + } /* Generate domain masks and attrs */ ndoms = generate_sched_domains(&doms, &attr); @@ -1013,11 +1191,11 @@ static void rebuild_sched_domains_locked(void) void rebuild_sched_domains(void) { - get_online_cpus(); + cpus_read_lock(); percpu_down_write(&cpuset_rwsem); rebuild_sched_domains_locked(); percpu_up_write(&cpuset_rwsem); - put_online_cpus(); + cpus_read_unlock(); } /** @@ -1025,17 +1203,25 @@ void rebuild_sched_domains(void) * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed * * Iterate through each task of @cs updating its cpus_allowed to the - * effective cpuset's. As this function is called with cpuset_mutex held, + * effective cpuset's. As this function is called with cpuset_rwsem held, * cpuset membership stays stable. */ 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); } @@ -1070,15 +1256,18 @@ enum subparts_cmd { partcmd_enable, /* Enable partition root */ partcmd_disable, /* Disable partition root */ partcmd_update, /* Update parent's subparts_cpus */ + partcmd_invalidate, /* Make partition invalid */ }; +static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, + int turning_on); /** * update_parent_subparts_cpumask - update subparts_cpus mask of parent cpuset * @cpuset: The cpuset that requests change in partition root state * @cmd: Partition root state change command * @newmask: Optional new cpumask for partcmd_update * @tmp: Temporary addmask and delmask - * Return: 0, 1 or an error code + * Return: 0 or a partition root state error code * * For partcmd_enable, the cpuset is being transformed from a non-partition * root to a partition root. The cpus_allowed mask of the given cpuset will @@ -1086,42 +1275,39 @@ enum subparts_cmd { * effective_cpus. The function will return 0 if all the CPUs listed in * cpus_allowed can be granted or an error code will be returned. * - * For partcmd_disable, the cpuset is being transofrmed from a partition - * root back to a non-partition root. any CPUs in cpus_allowed that are in + * For partcmd_disable, the cpuset is being transformed from a partition + * root back to a non-partition root. Any CPUs in cpus_allowed that are in * parent's subparts_cpus will be taken away from that cpumask and put back - * into parent's effective_cpus. 0 should always be returned. + * into parent's effective_cpus. 0 will always be returned. + * + * For partcmd_update, if the optional newmask is specified, the cpu list is + * to be changed from cpus_allowed to newmask. Otherwise, cpus_allowed is + * assumed to remain the same. The cpuset should either be a valid or invalid + * partition root. The partition root state may change from valid to invalid + * or vice versa. An error code will only be returned if transitioning from + * invalid to valid violates the exclusivity rule. * - * For partcmd_update, if the optional newmask is specified, the cpu - * list is to be changed from cpus_allowed to newmask. Otherwise, - * cpus_allowed is assumed to remain the same. The cpuset should either - * be a partition root or an invalid partition root. The partition root - * state may change if newmask is NULL and none of the requested CPUs can - * be granted by the parent. The function will return 1 if changes to - * parent's subparts_cpus and effective_cpus happen or 0 otherwise. - * Error code should only be returned when newmask is non-NULL. + * For partcmd_invalidate, the current partition will be made invalid. * * The partcmd_enable and partcmd_disable commands are used by - * update_prstate(). The partcmd_update command is used by - * update_cpumasks_hier() with newmask NULL and update_cpumask() with - * newmask set. - * - * The checking is more strict when enabling partition root than the - * other two commands. - * - * Because of the implicit cpu exclusive nature of a partition root, - * cpumask changes that violates the cpu exclusivity rule will not be - * permitted when checked by validate_change(). The validate_change() - * function will also prevent any changes to the cpu list if it is not - * a superset of children's cpu lists. + * update_prstate(). An error code may be returned and the caller will check + * for error. + * + * The partcmd_update command is used by update_cpumasks_hier() with newmask + * NULL and update_cpumask() with newmask set. The partcmd_invalidate is used + * by update_cpumask() with NULL newmask. In both cases, the callers won't + * check for error and so partition_root_state and prs_error will be updated + * directly. */ -static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, +static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, struct cpumask *newmask, struct tmpmasks *tmp) { - struct cpuset *parent = parent_cs(cpuset); + struct cpuset *parent = parent_cs(cs); int adding; /* Moving cpus from effective_cpus to subparts_cpus */ int deleting; /* Moving cpus from subparts_cpus to effective_cpus */ - bool part_error = false; /* Partition error? */ + int old_prs, new_prs; + int part_error = PERR_NONE; /* Partition error? */ percpu_rwsem_assert_held(&cpuset_rwsem); @@ -1130,124 +1316,164 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, * The new cpumask, if present, or the current cpus_allowed must * not be empty. */ - if (!is_partition_root(parent) || - (newmask && cpumask_empty(newmask)) || - (!newmask && cpumask_empty(cpuset->cpus_allowed))) - return -EINVAL; - - /* - * Enabling/disabling partition root is not allowed if there are - * online children. - */ - if ((cmd != partcmd_update) && css_has_online_children(&cpuset->css)) - return -EBUSY; - - /* - * Enabling partition root is not allowed if not all the CPUs - * can be granted from parent's effective_cpus or at least one - * CPU will be left after that. - */ - if ((cmd == partcmd_enable) && - (!cpumask_subset(cpuset->cpus_allowed, parent->effective_cpus) || - cpumask_equal(cpuset->cpus_allowed, parent->effective_cpus))) - return -EINVAL; + if (!is_partition_valid(parent)) { + return is_partition_invalid(parent) + ? PERR_INVPARENT : PERR_NOTPART; + } + if ((newmask && cpumask_empty(newmask)) || + (!newmask && cpumask_empty(cs->cpus_allowed))) + return PERR_CPUSEMPTY; /* - * A cpumask update cannot make parent's effective_cpus become empty. + * new_prs will only be changed for the partcmd_update and + * partcmd_invalidate commands. */ adding = deleting = false; + old_prs = new_prs = cs->partition_root_state; if (cmd == partcmd_enable) { - cpumask_copy(tmp->addmask, cpuset->cpus_allowed); + /* + * Enabling partition root is not allowed if cpus_allowed + * doesn't overlap parent's cpus_allowed. + */ + if (!cpumask_intersects(cs->cpus_allowed, parent->cpus_allowed)) + return PERR_INVCPUS; + + /* + * A parent can be left with no CPU as long as there is no + * task directly associated with the parent partition. + */ + if (!cpumask_intersects(cs->cpus_allowed, parent->effective_cpus) && + partition_is_populated(parent, cs)) + return PERR_NOCPUS; + + cpumask_copy(tmp->addmask, cs->cpus_allowed); adding = true; } else if (cmd == partcmd_disable) { - deleting = cpumask_and(tmp->delmask, cpuset->cpus_allowed, + /* + * Need to remove cpus from parent's subparts_cpus for valid + * partition root. + */ + deleting = !is_prs_invalid(old_prs) && + cpumask_and(tmp->delmask, cs->cpus_allowed, parent->subparts_cpus); + } else if (cmd == partcmd_invalidate) { + if (is_prs_invalid(old_prs)) + return 0; + + /* + * Make the current partition invalid. It is assumed that + * invalidation is caused by violating cpu exclusivity rule. + */ + deleting = cpumask_and(tmp->delmask, cs->cpus_allowed, + parent->subparts_cpus); + if (old_prs > 0) { + new_prs = -old_prs; + part_error = PERR_NOTEXCL; + } } else if (newmask) { /* * partcmd_update with newmask: * + * Compute add/delete mask to/from subparts_cpus + * * delmask = cpus_allowed & ~newmask & parent->subparts_cpus - * addmask = newmask & parent->effective_cpus + * addmask = newmask & parent->cpus_allowed * & ~parent->subparts_cpus */ - cpumask_andnot(tmp->delmask, cpuset->cpus_allowed, newmask); + cpumask_andnot(tmp->delmask, cs->cpus_allowed, newmask); deleting = cpumask_and(tmp->delmask, tmp->delmask, parent->subparts_cpus); - cpumask_and(tmp->addmask, newmask, parent->effective_cpus); + cpumask_and(tmp->addmask, newmask, parent->cpus_allowed); adding = cpumask_andnot(tmp->addmask, tmp->addmask, parent->subparts_cpus); /* - * Return error if the new effective_cpus could become empty. + * Make partition invalid if parent's effective_cpus could + * become empty and there are tasks in the parent. */ if (adding && - cpumask_equal(parent->effective_cpus, tmp->addmask)) { - if (!deleting) - return -EINVAL; - /* - * As some of the CPUs in subparts_cpus might have - * been offlined, we need to compute the real delmask - * to confirm that. - */ - if (!cpumask_and(tmp->addmask, tmp->delmask, - cpu_active_mask)) - return -EINVAL; - cpumask_copy(tmp->addmask, parent->effective_cpus); + cpumask_subset(parent->effective_cpus, tmp->addmask) && + !cpumask_intersects(tmp->delmask, cpu_active_mask) && + partition_is_populated(parent, cs)) { + part_error = PERR_NOCPUS; + adding = false; + deleting = cpumask_and(tmp->delmask, cs->cpus_allowed, + parent->subparts_cpus); } } else { /* * partcmd_update w/o newmask: * - * addmask = cpus_allowed & parent->effectiveb_cpus + * delmask = cpus_allowed & parent->subparts_cpus + * addmask = cpus_allowed & parent->cpus_allowed + * & ~parent->subparts_cpus * - * Note that parent's subparts_cpus may have been - * pre-shrunk in case there is a change in the cpu list. - * So no deletion is needed. + * This gets invoked either due to a hotplug event or from + * update_cpumasks_hier(). This can cause the state of a + * partition root to transition from valid to invalid or vice + * versa. So we still need to compute the addmask and delmask. + + * A partition error happens when: + * 1) Cpuset is valid partition, but parent does not distribute + * out any CPUs. + * 2) Parent has tasks and all its effective CPUs will have + * to be distributed out. */ - adding = cpumask_and(tmp->addmask, cpuset->cpus_allowed, - parent->effective_cpus); - part_error = cpumask_equal(tmp->addmask, - parent->effective_cpus); + cpumask_and(tmp->addmask, cs->cpus_allowed, + parent->cpus_allowed); + adding = cpumask_andnot(tmp->addmask, tmp->addmask, + parent->subparts_cpus); + + if ((is_partition_valid(cs) && !parent->nr_subparts_cpus) || + (adding && + cpumask_subset(parent->effective_cpus, tmp->addmask) && + partition_is_populated(parent, cs))) { + part_error = PERR_NOCPUS; + adding = false; + } + + if (part_error && is_partition_valid(cs) && + parent->nr_subparts_cpus) + deleting = cpumask_and(tmp->delmask, cs->cpus_allowed, + parent->subparts_cpus); } + if (part_error) + WRITE_ONCE(cs->prs_err, part_error); if (cmd == partcmd_update) { - int prev_prs = cpuset->partition_root_state; - /* - * Check for possible transition between PRS_ENABLED - * and PRS_ERROR. + * Check for possible transition between valid and invalid + * partition root. */ - switch (cpuset->partition_root_state) { - case PRS_ENABLED: + switch (cs->partition_root_state) { + case PRS_ROOT: + case PRS_ISOLATED: if (part_error) - cpuset->partition_root_state = PRS_ERROR; + new_prs = -old_prs; break; - case PRS_ERROR: + case PRS_INVALID_ROOT: + case PRS_INVALID_ISOLATED: if (!part_error) - cpuset->partition_root_state = PRS_ENABLED; + new_prs = -old_prs; break; } - /* - * Set part_error if previously in invalid state. - */ - part_error = (prev_prs == PRS_ERROR); } - if (!part_error && (cpuset->partition_root_state == PRS_ERROR)) - return 0; /* Nothing need to be done */ + if (!adding && !deleting && (new_prs == old_prs)) + return 0; - if (cpuset->partition_root_state == PRS_ERROR) { - /* - * Remove all its cpus from parent's subparts_cpus. - */ - adding = false; - deleting = cpumask_and(tmp->delmask, cpuset->cpus_allowed, - parent->subparts_cpus); + /* + * Transitioning between invalid to valid or vice versa may require + * changing CS_CPU_EXCLUSIVE and CS_SCHED_LOAD_BALANCE. + */ + if (old_prs != new_prs) { + if (is_prs_invalid(old_prs) && !is_cpu_exclusive(cs) && + (update_flag(CS_CPU_EXCLUSIVE, cs, 1) < 0)) + return PERR_NOTEXCL; + if (is_prs_invalid(new_prs) && is_cpu_exclusive(cs)) + update_flag(CS_CPU_EXCLUSIVE, cs, 0); } - if (!adding && !deleting) - return 0; - /* * Change the parent's subparts_cpus. * Newly added CPUs will be removed from effective_cpus and @@ -1272,40 +1498,68 @@ static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, } parent->nr_subparts_cpus = cpumask_weight(parent->subparts_cpus); + + if (old_prs != new_prs) + cs->partition_root_state = new_prs; + spin_unlock_irq(&callback_lock); - return cmd == partcmd_update; + if (adding || deleting) + update_tasks_cpumask(parent); + + /* + * Set or clear CS_SCHED_LOAD_BALANCE when partcmd_update, if necessary. + * rebuild_sched_domains_locked() may be called. + */ + if (old_prs != new_prs) { + if (old_prs == PRS_ISOLATED) + update_flag(CS_SCHED_LOAD_BALANCE, cs, 1); + else if (new_prs == PRS_ISOLATED) + update_flag(CS_SCHED_LOAD_BALANCE, cs, 0); + } + notify_partition_change(cs, old_prs); + return 0; } /* * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree * @cs: the cpuset to consider * @tmp: temp variables for calculating effective_cpus & partition setup + * @force: don't skip any descendant cpusets if set * - * When congifured cpumask is changed, the effective cpumasks of this cpuset + * When configured cpumask is changed, the effective cpumasks of this cpuset * and all its descendants need to be updated. * - * On legacy hierachy, effective_cpus will be the same with cpu_allowed. + * On legacy hierarchy, effective_cpus will be the same with cpu_allowed. * - * Called with cpuset_mutex held + * Called with cpuset_rwsem held */ -static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) +static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, + bool force) { struct cpuset *cp; struct cgroup_subsys_state *pos_css; bool need_rebuild_sched_domains = false; + int old_prs, new_prs; rcu_read_lock(); cpuset_for_each_descendant_pre(cp, pos_css, cs) { struct cpuset *parent = parent_cs(cp); + bool update_parent = false; compute_effective_cpumask(tmp->new_cpus, cp, parent); /* * If it becomes empty, inherit the effective mask of the - * parent, which is guaranteed to have some CPUs. + * parent, which is guaranteed to have some CPUs unless + * it is a partition root that has explicitly distributed + * out all its CPUs. */ if (is_in_v2_mode() && cpumask_empty(tmp->new_cpus)) { + if (is_partition_valid(cp) && + cpumask_equal(cp->cpus_allowed, cp->subparts_cpus)) + goto update_parent_subparts; + cpumask_copy(tmp->new_cpus, parent->effective_cpus); if (!cp->use_parent_ecpus) { cp->use_parent_ecpus = true; @@ -1319,56 +1573,40 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) /* * Skip the whole subtree if the cpumask remains the same - * and has no partition root state. + * and has no partition root state and force flag not set. */ - if (!cp->partition_root_state && + if (!cp->partition_root_state && !force && cpumask_equal(tmp->new_cpus, cp->effective_cpus)) { pos_css = css_rightmost_descendant(pos_css); continue; } +update_parent_subparts: /* * update_parent_subparts_cpumask() should have been called * for cs already in update_cpumask(). We should also call * update_tasks_cpumask() again for tasks in the parent * cpuset if the parent's subparts_cpus changes. */ - if ((cp != cs) && cp->partition_root_state) { + old_prs = new_prs = cp->partition_root_state; + if ((cp != cs) && old_prs) { switch (parent->partition_root_state) { - case PRS_DISABLED: - /* - * If parent is not a partition root or an - * invalid partition root, clear the state - * state and the CS_CPU_EXCLUSIVE flag. - */ - WARN_ON_ONCE(cp->partition_root_state - != PRS_ERROR); - cp->partition_root_state = 0; - - /* - * clear_bit() is an atomic operation and - * readers aren't interested in the state - * of CS_CPU_EXCLUSIVE anyway. So we can - * just update the flag without holding - * the callback_lock. - */ - clear_bit(CS_CPU_EXCLUSIVE, &cp->flags); - break; - - case PRS_ENABLED: - if (update_parent_subparts_cpumask(cp, partcmd_update, NULL, tmp)) - update_tasks_cpumask(parent); + case PRS_ROOT: + case PRS_ISOLATED: + update_parent = true; break; - case PRS_ERROR: + default: /* - * When parent is invalid, it has to be too. + * When parent is not a partition root or is + * invalid, child partition roots become + * invalid too. */ - cp->partition_root_state = PRS_ERROR; - if (cp->nr_subparts_cpus) { - cp->nr_subparts_cpus = 0; - cpumask_clear(cp->subparts_cpus); - } + if (is_partition_valid(cp)) + new_prs = -cp->partition_root_state; + WRITE_ONCE(cp->prs_err, + is_partition_invalid(parent) + ? PERR_INVPARENT : PERR_NOTPART); break; } } @@ -1377,39 +1615,45 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) continue; rcu_read_unlock(); + if (update_parent) { + update_parent_subparts_cpumask(cp, partcmd_update, NULL, + tmp); + /* + * The cpuset partition_root_state may become + * invalid. Capture it. + */ + new_prs = cp->partition_root_state; + } + spin_lock_irq(&callback_lock); - cpumask_copy(cp->effective_cpus, tmp->new_cpus); - if (cp->nr_subparts_cpus && - (cp->partition_root_state != PRS_ENABLED)) { + if (cp->nr_subparts_cpus && !is_partition_valid(cp)) { + /* + * Put all active subparts_cpus back to effective_cpus. + */ + cpumask_or(tmp->new_cpus, tmp->new_cpus, + cp->subparts_cpus); + cpumask_and(tmp->new_cpus, tmp->new_cpus, + cpu_active_mask); cp->nr_subparts_cpus = 0; cpumask_clear(cp->subparts_cpus); - } else if (cp->nr_subparts_cpus) { + } + + cpumask_copy(cp->effective_cpus, tmp->new_cpus); + if (cp->nr_subparts_cpus) { /* * Make sure that effective_cpus & subparts_cpus * are mutually exclusive. - * - * In the unlikely event that effective_cpus - * becomes empty. we clear cp->nr_subparts_cpus and - * let its child partition roots to compete for - * CPUs again. */ cpumask_andnot(cp->effective_cpus, cp->effective_cpus, cp->subparts_cpus); - if (cpumask_empty(cp->effective_cpus)) { - cpumask_copy(cp->effective_cpus, tmp->new_cpus); - cpumask_clear(cp->subparts_cpus); - cp->nr_subparts_cpus = 0; - } else if (!cpumask_subset(cp->subparts_cpus, - tmp->new_cpus)) { - cpumask_andnot(cp->subparts_cpus, - cp->subparts_cpus, tmp->new_cpus); - cp->nr_subparts_cpus - = cpumask_weight(cp->subparts_cpus); - } } + + cp->partition_root_state = new_prs; spin_unlock_irq(&callback_lock); + notify_partition_change(cp, old_prs); + WARN_ON(!is_in_v2_mode() && !cpumask_equal(cp->cpus_allowed, cp->effective_cpus)); @@ -1424,7 +1668,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) if (!cpumask_empty(cp->cpus_allowed) && is_sched_load_balance(cp) && (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) || - is_partition_root(cp))) + is_partition_valid(cp))) need_rebuild_sched_domains = true; rcu_read_lock(); @@ -1448,10 +1692,15 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs, struct cpuset *sibling; struct cgroup_subsys_state *pos_css; + percpu_rwsem_assert_held(&cpuset_rwsem); + /* * Check all its siblings and call update_cpumasks_hier() * if their use_parent_ecpus flag is set in order for them * to use the right effective_cpus value. + * + * The update_cpumasks_hier() function may sleep. So we have to + * release the RCU read lock before calling it. */ rcu_read_lock(); cpuset_for_each_child(sibling, pos_css, parent) { @@ -1459,8 +1708,13 @@ static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs, continue; if (!sibling->use_parent_ecpus) continue; + if (!css_tryget_online(&sibling->css)) + continue; - update_cpumasks_hier(sibling, tmp); + rcu_read_unlock(); + update_cpumasks_hier(sibling, tmp, false); + rcu_read_lock(); + css_put(&sibling->css); } rcu_read_unlock(); } @@ -1476,6 +1730,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, { int retval; struct tmpmasks tmp; + bool invalidate = false; /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */ if (cs == &top_cpuset) @@ -1503,10 +1758,6 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed)) return 0; - retval = validate_change(cs, trialcs); - if (retval < 0) - return retval; - #ifdef CONFIG_CPUMASK_OFFSTACK /* * Use the cpumasks in trialcs for tmpmasks when they are pointers @@ -1517,29 +1768,70 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, tmp.new_cpus = trialcs->cpus_allowed; #endif + retval = validate_change(cs, trialcs); + + if ((retval == -EINVAL) && cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) { + struct cpuset *cp, *parent; + struct cgroup_subsys_state *css; + + /* + * The -EINVAL error code indicates that partition sibling + * CPU exclusivity rule has been violated. We still allow + * the cpumask change to proceed while invalidating the + * partition. However, any conflicting sibling partitions + * have to be marked as invalid too. + */ + invalidate = true; + rcu_read_lock(); + parent = parent_cs(cs); + cpuset_for_each_child(cp, css, parent) + if (is_partition_valid(cp) && + cpumask_intersects(trialcs->cpus_allowed, cp->cpus_allowed)) { + rcu_read_unlock(); + update_parent_subparts_cpumask(cp, partcmd_invalidate, NULL, &tmp); + rcu_read_lock(); + } + rcu_read_unlock(); + retval = 0; + } + if (retval < 0) + return retval; + if (cs->partition_root_state) { - /* Cpumask of a partition root cannot be empty */ - if (cpumask_empty(trialcs->cpus_allowed)) - return -EINVAL; - if (update_parent_subparts_cpumask(cs, partcmd_update, - trialcs->cpus_allowed, &tmp) < 0) - return -EINVAL; + if (invalidate) + update_parent_subparts_cpumask(cs, partcmd_invalidate, + NULL, &tmp); + else + update_parent_subparts_cpumask(cs, partcmd_update, + trialcs->cpus_allowed, &tmp); } + compute_effective_cpumask(trialcs->effective_cpus, trialcs, + parent_cs(cs)); spin_lock_irq(&callback_lock); cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed); /* - * Make sure that subparts_cpus is a subset of cpus_allowed. + * Make sure that subparts_cpus, if not empty, is a subset of + * cpus_allowed. Clear subparts_cpus if partition not valid or + * empty effective cpus with tasks. */ if (cs->nr_subparts_cpus) { - cpumask_andnot(cs->subparts_cpus, cs->subparts_cpus, - cs->cpus_allowed); - cs->nr_subparts_cpus = cpumask_weight(cs->subparts_cpus); + if (!is_partition_valid(cs) || + (cpumask_subset(trialcs->effective_cpus, cs->subparts_cpus) && + partition_is_populated(cs, NULL))) { + cs->nr_subparts_cpus = 0; + cpumask_clear(cs->subparts_cpus); + } else { + cpumask_and(cs->subparts_cpus, cs->subparts_cpus, + cs->cpus_allowed); + cs->nr_subparts_cpus = cpumask_weight(cs->subparts_cpus); + } } spin_unlock_irq(&callback_lock); - update_cpumasks_hier(cs, &tmp); + /* effective_cpus will be updated here */ + update_cpumasks_hier(cs, &tmp, false); if (cs->partition_root_state) { struct cpuset *parent = parent_cs(cs); @@ -1585,6 +1877,11 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, { struct cpuset_migrate_mm_work *mwork; + if (nodes_equal(*from, *to)) { + mmput(mm); + return; + } + mwork = kzalloc(sizeof(*mwork), GFP_KERNEL); if (mwork) { mwork->mm = mm; @@ -1637,12 +1934,12 @@ static void *cpuset_being_rebound; * @cs: the cpuset in which each task's mems_allowed mask needs to be changed * * Iterate through each task of @cs updating its mems_allowed to the - * effective cpuset's. As this function is called with cpuset_mutex held, + * effective cpuset's. As this function is called with cpuset_rwsem held, * cpuset membership stays stable. */ static void update_tasks_nodemask(struct cpuset *cs) { - static nodemask_t newmems; /* protected by cpuset_mutex */ + static nodemask_t newmems; /* protected by cpuset_rwsem */ struct css_task_iter it; struct task_struct *task; @@ -1651,11 +1948,11 @@ static void update_tasks_nodemask(struct cpuset *cs) guarantee_online_mems(cs, &newmems); /* - * The mpol_rebind_mm() call takes mmap_sem, which we couldn't + * The mpol_rebind_mm() call takes mmap_lock, which we couldn't * take while holding tasklist_lock. Forks can happen - the * mpol_dup() cpuset_being_rebound check will catch such forks, * and rebind their vma mempolicies too. Because we still hold - * the global cpuset_mutex, we know that no other rebind effort + * the global cpuset_rwsem, we know that no other rebind effort * will be contending for the global variable cpuset_being_rebound. * It's ok if we rebind the same mm twice; mpol_rebind_mm() * is idempotent. Also migrate pages in each mm to new nodes. @@ -1699,9 +1996,9 @@ static void update_tasks_nodemask(struct cpuset *cs) * When configured nodemask is changed, the effective nodemasks of this cpuset * and all its descendants need to be updated. * - * On legacy hiearchy, effective_mems will be the same with mems_allowed. + * On legacy hierarchy, effective_mems will be the same with mems_allowed. * - * Called with cpuset_mutex held + * Called with cpuset_rwsem held */ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems) { @@ -1754,9 +2051,9 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems) * mempolicies and if the cpuset is marked 'memory_migrate', * migrate the tasks pages to the new memory. * - * Call with cpuset_mutex held. May take callback_lock during call. + * Call with cpuset_rwsem held. May take callback_lock during call. * Will take tasklist_lock, scan tasklist for tasks in cpuset cs, - * lock each such tasks mm->mmap_sem, scan its vma's and rebind + * lock each such tasks mm->mmap_lock, scan its vma's and rebind * their mempolicies to the cpusets new mems_allowed. */ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, @@ -1801,6 +2098,8 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, if (retval < 0) goto done; + check_insane_mems_config(&trialcs->mems_allowed); + spin_lock_irq(&callback_lock); cs->mems_allowed = trialcs->mems_allowed; spin_unlock_irq(&callback_lock); @@ -1844,7 +2143,7 @@ static int update_relax_domain_level(struct cpuset *cs, s64 val) * @cs: the cpuset in which each task's spread flags needs to be changed * * Iterate through each task of @cs updating its spread flags. As this - * function is called with cpuset_mutex held, cpuset membership stays + * function is called with cpuset_rwsem held, cpuset membership stays * stable. */ static void update_tasks_flags(struct cpuset *cs) @@ -1864,7 +2163,7 @@ static void update_tasks_flags(struct cpuset *cs) * cs: the cpuset to update * turning_on: whether the flag is being set or cleared * - * Call with cpuset_mutex held. + * Call with cpuset_rwsem held. */ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, @@ -1908,92 +2207,130 @@ out: return err; } -/* - * update_prstate - update partititon_root_state - * cs: the cpuset to update - * val: 0 - disabled, 1 - enabled +/** + * update_prstate - update partition_root_state + * @cs: the cpuset to update + * @new_prs: new partition root state + * Return: 0 if successful, != 0 if error * - * Call with cpuset_mutex held. + * Call with cpuset_rwsem held. */ -static int update_prstate(struct cpuset *cs, int val) +static int update_prstate(struct cpuset *cs, int new_prs) { - int err; + int err = PERR_NONE, old_prs = cs->partition_root_state; + bool sched_domain_rebuilt = false; struct cpuset *parent = parent_cs(cs); - struct tmpmasks tmp; + struct tmpmasks tmpmask; - if ((val != 0) && (val != 1)) - return -EINVAL; - if (val == cs->partition_root_state) + if (old_prs == new_prs) return 0; /* - * Cannot force a partial or invalid partition root to a full - * partition root. + * For a previously invalid partition root, leave it at being + * invalid if new_prs is not "member". */ - if (val && cs->partition_root_state) - return -EINVAL; + if (new_prs && is_prs_invalid(old_prs)) { + cs->partition_root_state = -new_prs; + return 0; + } - if (alloc_cpumasks(NULL, &tmp)) + if (alloc_cpumasks(NULL, &tmpmask)) return -ENOMEM; - err = -EINVAL; - if (!cs->partition_root_state) { + if (!old_prs) { /* * Turning on partition root requires setting the * CS_CPU_EXCLUSIVE bit implicitly as well and cpus_allowed - * cannot be NULL. + * cannot be empty. */ - if (cpumask_empty(cs->cpus_allowed)) + if (cpumask_empty(cs->cpus_allowed)) { + err = PERR_CPUSEMPTY; goto out; + } err = update_flag(CS_CPU_EXCLUSIVE, cs, 1); - if (err) + if (err) { + err = PERR_NOTEXCL; goto out; + } err = update_parent_subparts_cpumask(cs, partcmd_enable, - NULL, &tmp); + NULL, &tmpmask); if (err) { update_flag(CS_CPU_EXCLUSIVE, cs, 0); goto out; } - cs->partition_root_state = PRS_ENABLED; + + if (new_prs == PRS_ISOLATED) { + /* + * Disable the load balance flag should not return an + * error unless the system is running out of memory. + */ + update_flag(CS_SCHED_LOAD_BALANCE, cs, 0); + sched_domain_rebuilt = true; + } + } else if (old_prs && new_prs) { + /* + * A change in load balance state only, no change in cpumasks. + */ + update_flag(CS_SCHED_LOAD_BALANCE, cs, (new_prs != PRS_ISOLATED)); + sched_domain_rebuilt = true; + goto out; /* Sched domain is rebuilt in update_flag() */ } else { /* - * Turning off partition root will clear the - * CS_CPU_EXCLUSIVE bit. + * Switching back to member is always allowed even if it + * disables child partitions. */ - if (cs->partition_root_state == PRS_ERROR) { - cs->partition_root_state = 0; - update_flag(CS_CPU_EXCLUSIVE, cs, 0); - err = 0; - goto out; - } + update_parent_subparts_cpumask(cs, partcmd_disable, NULL, + &tmpmask); - err = update_parent_subparts_cpumask(cs, partcmd_disable, - NULL, &tmp); - if (err) - goto out; - - cs->partition_root_state = 0; + /* + * If there are child partitions, they will all become invalid. + */ + if (unlikely(cs->nr_subparts_cpus)) { + spin_lock_irq(&callback_lock); + cs->nr_subparts_cpus = 0; + cpumask_clear(cs->subparts_cpus); + compute_effective_cpumask(cs->effective_cpus, cs, parent); + spin_unlock_irq(&callback_lock); + } /* Turning off CS_CPU_EXCLUSIVE will not return error */ update_flag(CS_CPU_EXCLUSIVE, cs, 0); + + if (!is_sched_load_balance(cs)) { + /* Make sure load balance is on */ + update_flag(CS_SCHED_LOAD_BALANCE, cs, 1); + sched_domain_rebuilt = true; + } } - /* - * 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); + update_sibling_cpumasks(parent, cs, &tmpmask); - rebuild_sched_domains_locked(); + if (!sched_domain_rebuilt) + rebuild_sched_domains_locked(); out: - free_cpumasks(NULL, &tmp); - return err; + /* + * Make partition invalid if an error happen + */ + if (err) + new_prs = -new_prs; + spin_lock_irq(&callback_lock); + cs->partition_root_state = new_prs; + spin_unlock_irq(&callback_lock); + /* + * Update child cpusets, if present. + * Force update if switching back to member. + */ + if (!list_empty(&cs->css.children)) + update_cpumasks_hier(cs, &tmpmask, !new_prs); + + notify_partition_change(cs, old_prs); + free_cpumasks(NULL, &tmpmask); + return 0; } /* @@ -2099,7 +2436,7 @@ static int fmeter_getrate(struct fmeter *fmp) static struct cpuset *cpuset_attach_old_cs; -/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */ +/* Called by cgroups to determine if a cpuset is usable; cpuset_rwsem held */ static int cpuset_can_attach(struct cgroup_taskset *tset) { struct cgroup_subsys_state *css; @@ -2119,8 +2456,14 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))) goto out_unlock; + /* + * Task cannot be moved to a cpuset with empty effective cpus. + */ + if (cpumask_empty(cs->effective_cpus)) + goto out_unlock; + cgroup_taskset_for_each(task, css, tset) { - ret = task_can_attach(task, cs->cpus_allowed); + ret = task_can_attach(task, cs->effective_cpus); if (ret) goto out_unlock; ret = security_task_setscheduler(task); @@ -2151,7 +2494,7 @@ static void cpuset_cancel_attach(struct cgroup_taskset *tset) } /* - * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach() + * Protected by cpuset_rwsem. cpus_attach is used only by cpuset_attach() * but we can't allocate it dynamically there. Define it global and * allocate from cpuset_init(). */ @@ -2159,7 +2502,7 @@ static cpumask_var_t cpus_attach; static void cpuset_attach(struct cgroup_taskset *tset) { - /* static buf protected by cpuset_mutex */ + /* static buf protected by cpuset_rwsem */ static nodemask_t cpuset_attach_nodemask_to; struct task_struct *task; struct task_struct *leader; @@ -2170,17 +2513,16 @@ 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() */ percpu_down_write(&cpuset_rwsem); - /* prepare for attach */ - if (cs == &top_cpuset) - cpumask_copy(cpus_attach, cpu_possible_mask); - else - guarantee_online_cpus(cs, cpus_attach); - guarantee_online_mems(cs, &cpuset_attach_nodemask_to); cgroup_taskset_for_each(task, css, tset) { + if (cs != &top_cpuset) + guarantee_online_cpus(task, cpus_attach); + else + cpumask_copy(cpus_attach, task_cpu_possible_mask(task)); /* * can_attach beforehand should guarantee that this doesn't * fail. TODO: have a better way to handle failure here @@ -2255,7 +2597,7 @@ 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(); + cpus_read_lock(); percpu_down_write(&cpuset_rwsem); if (!is_cpuset_online(cs)) { retval = -ENODEV; @@ -2293,7 +2635,7 @@ static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft, } out_unlock: percpu_up_write(&cpuset_rwsem); - put_online_cpus(); + cpus_read_unlock(); return retval; } @@ -2304,7 +2646,7 @@ 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(); + cpus_read_lock(); percpu_down_write(&cpuset_rwsem); if (!is_cpuset_online(cs)) goto out_unlock; @@ -2319,7 +2661,7 @@ static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft, } out_unlock: percpu_up_write(&cpuset_rwsem); - put_online_cpus(); + cpus_read_unlock(); return retval; } @@ -2351,14 +2693,14 @@ static ssize_t cpuset_write_resmask(struct kernfs_open_file *of, * operation like this one can lead to a deadlock through kernfs * active_ref protection. Let's break the protection. Losing the * protection is okay as we check whether @cs is online after - * grabbing cpuset_mutex anyway. This only happens on the legacy + * grabbing cpuset_rwsem anyway. This only happens on the legacy * hierarchies. */ css_get(&cs->css); kernfs_break_active_protection(of->kn); flush_work(&cpuset_hotplug_work); - get_online_cpus(); + cpus_read_lock(); percpu_down_write(&cpuset_rwsem); if (!is_cpuset_online(cs)) goto out_unlock; @@ -2384,7 +2726,7 @@ static ssize_t cpuset_write_resmask(struct kernfs_open_file *of, free_cpuset(trialcs); out_unlock: percpu_up_write(&cpuset_rwsem); - put_online_cpus(); + cpus_read_unlock(); kernfs_unbreak_active_protection(of->kn); css_put(&cs->css); flush_workqueue(cpuset_migrate_mm_wq); @@ -2473,23 +2815,36 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft) BUG(); } - /* Unrechable but makes gcc happy */ + /* Unreachable but makes gcc happy */ return 0; } static int sched_partition_show(struct seq_file *seq, void *v) { struct cpuset *cs = css_cs(seq_css(seq)); + const char *err, *type = NULL; switch (cs->partition_root_state) { - case PRS_ENABLED: + case PRS_ROOT: seq_puts(seq, "root\n"); break; - case PRS_DISABLED: + case PRS_ISOLATED: + seq_puts(seq, "isolated\n"); + break; + case PRS_MEMBER: seq_puts(seq, "member\n"); break; - case PRS_ERROR: - seq_puts(seq, "root invalid\n"); + case PRS_INVALID_ROOT: + type = "root"; + fallthrough; + case PRS_INVALID_ISOLATED: + if (!type) + type = "isolated"; + err = perr_strings[READ_ONCE(cs->prs_err)]; + if (err) + seq_printf(seq, "%s invalid (%s)\n", type, err); + else + seq_printf(seq, "%s invalid\n", type); break; } return 0; @@ -2508,14 +2863,16 @@ static ssize_t sched_partition_write(struct kernfs_open_file *of, char *buf, * Convert "root" to ENABLED, and convert "member" to DISABLED. */ if (!strcmp(buf, "root")) - val = PRS_ENABLED; + val = PRS_ROOT; else if (!strcmp(buf, "member")) - val = PRS_DISABLED; + val = PRS_MEMBER; + else if (!strcmp(buf, "isolated")) + val = PRS_ISOLATED; else return -EINVAL; css_get(&cs->css); - get_online_cpus(); + cpus_read_lock(); percpu_down_write(&cpuset_rwsem); if (!is_cpuset_online(cs)) goto out_unlock; @@ -2523,7 +2880,7 @@ static ssize_t sched_partition_write(struct kernfs_open_file *of, char *buf, retval = update_prstate(cs, val); out_unlock: percpu_up_write(&cpuset_rwsem); - put_online_cpus(); + cpus_read_unlock(); css_put(&cs->css); return retval ?: nbytes; } @@ -2675,6 +3032,7 @@ static struct cftype dfl_files[] = { .write = sched_partition_write, .private = FILE_PARTITION_ROOT, .flags = CFTYPE_NOT_ON_ROOT, + .file_offset = offsetof(struct cpuset, partition_file), }, { @@ -2710,12 +3068,16 @@ cpuset_css_alloc(struct cgroup_subsys_state *parent_css) return ERR_PTR(-ENOMEM); } - set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags); + __set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags); nodes_clear(cs->mems_allowed); nodes_clear(cs->effective_mems); fmeter_init(&cs->fmeter); cs->relax_domain_level = -1; + /* Set CS_MEMORY_MIGRATE for default hierarchy */ + if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) + __set_bit(CS_MEMORY_MIGRATE, &cs->flags); + return &cs->css; } @@ -2729,7 +3091,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css) if (!parent) return 0; - get_online_cpus(); + cpus_read_lock(); percpu_down_write(&cpuset_rwsem); set_bit(CS_ONLINE, &cs->flags); @@ -2755,7 +3117,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css) /* * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is * set. This flag handling is implemented in cgroup core for - * histrical reasons - the flag may be specified during mount. + * historical reasons - the flag may be specified during mount. * * Currently, if any sibling cpusets have exclusive cpus or mem, we * refuse to clone the configuration - thereby refusing the task to @@ -2782,7 +3144,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css) spin_unlock_irq(&callback_lock); out_unlock: percpu_up_write(&cpuset_rwsem); - put_online_cpus(); + cpus_read_unlock(); return 0; } @@ -2801,10 +3163,10 @@ static void cpuset_css_offline(struct cgroup_subsys_state *css) { struct cpuset *cs = css_cs(css); - get_online_cpus(); + cpus_read_lock(); percpu_down_write(&cpuset_rwsem); - if (is_partition_root(cs)) + if (is_partition_valid(cs)) update_prstate(cs, 0); if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && @@ -2822,7 +3184,7 @@ static void cpuset_css_offline(struct cgroup_subsys_state *css) clear_bit(CS_ONLINE, &cs->flags); percpu_up_write(&cpuset_rwsem); - put_online_cpus(); + cpus_read_unlock(); } static void cpuset_css_free(struct cgroup_subsys_state *css) @@ -2952,7 +3314,7 @@ hotplug_update_tasks_legacy(struct cpuset *cs, /* * Don't call update_tasks_cpumask() if the cpuset becomes empty, - * as the tasks will be migratecd to an ancestor. + * as the tasks will be migrated to an ancestor. */ if (cpus_updated && !cpumask_empty(cs->cpus_allowed)) update_tasks_cpumask(cs); @@ -2980,7 +3342,8 @@ hotplug_update_tasks(struct cpuset *cs, struct cpumask *new_cpus, nodemask_t *new_mems, bool cpus_updated, bool mems_updated) { - if (cpumask_empty(new_cpus)) + /* A partition root is allowed to have empty effective cpus */ + if (cpumask_empty(new_cpus) && !is_partition_valid(cs)) cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus); if (nodes_empty(*new_mems)) *new_mems = parent_cs(cs)->effective_mems; @@ -3033,7 +3396,7 @@ retry: goto retry; } - parent = parent_cs(cs); + parent = parent_cs(cs); compute_effective_cpumask(&new_cpus, cs, parent); nodes_and(new_mems, cs->mems_allowed, parent->effective_mems); @@ -3049,47 +3412,73 @@ retry: /* * In the unlikely event that a partition root has empty - * effective_cpus or its parent becomes erroneous, we have to - * transition it to the erroneous state. + * effective_cpus with tasks, we will have to invalidate child + * partitions, if present, by setting nr_subparts_cpus to 0 to + * reclaim their cpus. */ - if (is_partition_root(cs) && (cpumask_empty(&new_cpus) || - (parent->partition_root_state == PRS_ERROR))) { + if (cs->nr_subparts_cpus && is_partition_valid(cs) && + cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)) { + spin_lock_irq(&callback_lock); + cs->nr_subparts_cpus = 0; + cpumask_clear(cs->subparts_cpus); + spin_unlock_irq(&callback_lock); + compute_effective_cpumask(&new_cpus, cs, parent); + } + + /* + * Force the partition to become invalid if either one of + * the following conditions hold: + * 1) empty effective cpus but not valid empty partition. + * 2) parent is invalid or doesn't grant any cpus to child + * partitions. + */ + if (is_partition_valid(cs) && (!parent->nr_subparts_cpus || + (cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)))) { + int old_prs, parent_prs; + + update_parent_subparts_cpumask(cs, partcmd_disable, NULL, tmp); if (cs->nr_subparts_cpus) { + spin_lock_irq(&callback_lock); cs->nr_subparts_cpus = 0; cpumask_clear(cs->subparts_cpus); + spin_unlock_irq(&callback_lock); compute_effective_cpumask(&new_cpus, cs, parent); } - /* - * If the effective_cpus is empty because the child - * partitions take away all the CPUs, we can keep - * the current partition and let the child partitions - * fight for available CPUs. - */ - if ((parent->partition_root_state == PRS_ERROR) || - cpumask_empty(&new_cpus)) { - update_parent_subparts_cpumask(cs, partcmd_disable, - NULL, tmp); - cs->partition_root_state = PRS_ERROR; + old_prs = cs->partition_root_state; + parent_prs = parent->partition_root_state; + if (is_partition_valid(cs)) { + spin_lock_irq(&callback_lock); + make_partition_invalid(cs); + spin_unlock_irq(&callback_lock); + if (is_prs_invalid(parent_prs)) + WRITE_ONCE(cs->prs_err, PERR_INVPARENT); + else if (!parent_prs) + WRITE_ONCE(cs->prs_err, PERR_NOTPART); + else + WRITE_ONCE(cs->prs_err, PERR_HOTPLUG); + notify_partition_change(cs, old_prs); } cpuset_force_rebuild(); } /* - * On the other hand, an erroneous partition root may be transitioned - * back to a regular one or a partition root with no CPU allocated - * from the parent may change to erroneous. + * On the other hand, an invalid partition root may be transitioned + * back to a regular one. */ - if (is_partition_root(parent) && - ((cs->partition_root_state == PRS_ERROR) || - !cpumask_intersects(&new_cpus, parent->subparts_cpus)) && - update_parent_subparts_cpumask(cs, partcmd_update, NULL, tmp)) - cpuset_force_rebuild(); + else if (is_partition_valid(parent) && is_partition_invalid(cs)) { + update_parent_subparts_cpumask(cs, partcmd_update, NULL, tmp); + if (is_partition_valid(cs)) + cpuset_force_rebuild(); + } update_tasks: cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus); mems_updated = !nodes_equal(new_mems, cs->effective_mems); + if (mems_updated) + check_insane_mems_config(&new_mems); + if (is_in_v2_mode()) hotplug_update_tasks(cs, &new_cpus, &new_mems, cpus_updated, mems_updated); @@ -3141,6 +3530,13 @@ static void cpuset_hotplug_workfn(struct work_struct *work) cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus); mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems); + /* + * In the rare case that hotplug removes all the cpus in subparts_cpus, + * we assumed that cpus are updated. + */ + if (!cpus_updated && top_cpuset.nr_subparts_cpus) + cpus_updated = true; + /* synchronize cpus_allowed to cpu_active_mask */ if (cpus_updated) { spin_lock_irq(&callback_lock); @@ -3246,8 +3642,11 @@ static struct notifier_block cpuset_track_online_nodes_nb = { */ void __init cpuset_init_smp(void) { - cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask); - top_cpuset.mems_allowed = node_states[N_MEMORY]; + /* + * cpus_allowd/mems_allowed set to v2 values in the initial + * cpuset_bind() call will be reset to v1 values in another + * cpuset_bind() call when v1 cpuset is mounted. + */ top_cpuset.old_mems_allowed = top_cpuset.mems_allowed; cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask); @@ -3275,9 +3674,7 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) unsigned long flags; spin_lock_irqsave(&callback_lock, flags); - rcu_read_lock(); - guarantee_online_cpus(task_cs(tsk), pmask); - rcu_read_unlock(); + guarantee_online_cpus(tsk, pmask); spin_unlock_irqrestore(&callback_lock, flags); } @@ -3291,13 +3688,22 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) * which will not contain a sane cpumask during cases such as cpu hotplugging. * This is the absolute last resort for the scheduler and it is only used if * _every_ other avenue has been traveled. + * + * Returns true if the affinity of @tsk was changed, false otherwise. **/ -void cpuset_cpus_allowed_fallback(struct task_struct *tsk) +bool cpuset_cpus_allowed_fallback(struct task_struct *tsk) { + const struct cpumask *possible_mask = task_cpu_possible_mask(tsk); + const struct cpumask *cs_mask; + bool changed = false; + rcu_read_lock(); - do_set_cpus_allowed(tsk, is_in_v2_mode() ? - task_cs(tsk)->cpus_allowed : cpu_possible_mask); + cs_mask = task_cs(tsk)->cpus_allowed; + if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask)) { + do_set_cpus_allowed(tsk, cs_mask); + changed = true; + } rcu_read_unlock(); /* @@ -3317,6 +3723,7 @@ void cpuset_cpus_allowed_fallback(struct task_struct *tsk) * select_fallback_rq() will fix things ups and set cpu_possible_mask * if required. */ + return changed; } void __init cpuset_init_current_mems_allowed(void) @@ -3349,7 +3756,7 @@ nodemask_t cpuset_mems_allowed(struct task_struct *tsk) } /** - * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed + * cpuset_nodemask_valid_mems_allowed - check nodemask vs. current mems_allowed * @nodemask: the nodemask to be checked * * Are any of the nodes in the nodemask allowed in current->mems_allowed? @@ -3372,8 +3779,8 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs) return cs; } -/** - * cpuset_node_allowed - Can we allocate on a memory node? +/* + * __cpuset_node_allowed - Can we allocate on a memory node? * @node: is this an allowed node? * @gfp_mask: memory allocation flags * @@ -3415,7 +3822,7 @@ static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs) bool __cpuset_node_allowed(int node, gfp_t gfp_mask) { struct cpuset *cs; /* current cpuset ancestors */ - int allowed; /* is allocation in zone z allowed? */ + bool allowed; /* is allocation in zone z allowed? */ unsigned long flags; if (in_interrupt()) @@ -3544,8 +3951,8 @@ void cpuset_print_current_mems_allowed(void) int cpuset_memory_pressure_enabled __read_mostly; -/** - * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims. +/* + * __cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims. * * Keep a running average of the rate of synchronous (direct) * page reclaim efforts initiated by tasks in each cpuset. @@ -3560,7 +3967,7 @@ int cpuset_memory_pressure_enabled __read_mostly; * "memory_pressure". Value displayed is an integer * representing the recent rate of entry into the synchronous * (direct) page reclaim by any task attached to the cpuset. - **/ + */ void __cpuset_memory_pressure_bump(void) { @@ -3576,7 +3983,7 @@ void __cpuset_memory_pressure_bump(void) * - Used for /proc/<pid>/cpuset. * - No need to task_lock(tsk) on this tsk->cpuset reference, as it * doesn't really matter if tsk->cpuset changes after we read it, - * and we take cpuset_mutex, keeping cpuset_attach() from changing it + * and we take cpuset_rwsem, keeping cpuset_attach() from changing it * anyway. */ int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns, |