| /* |
| * kernel/cpuset.c |
| * |
| * Processor and Memory placement constraints for sets of tasks. |
| * |
| * Copyright (C) 2003 BULL SA. |
| * Copyright (C) 2004-2007 Silicon Graphics, Inc. |
| * Copyright (C) 2006 Google, Inc |
| * |
| * Portions derived from Patrick Mochel's sysfs code. |
| * sysfs is Copyright (c) 2001-3 Patrick Mochel |
| * |
| * 2003-10-10 Written by Simon Derr. |
| * 2003-10-22 Updates by Stephen Hemminger. |
| * 2004 May-July Rework by Paul Jackson. |
| * 2006 Rework by Paul Menage to use generic cgroups |
| * 2008 Rework of the scheduler domains and CPU hotplug handling |
| * by Max Krasnyansky |
| * |
| * This file is subject to the terms and conditions of the GNU General Public |
| * License. See the file COPYING in the main directory of the Linux |
| * distribution for more details. |
| */ |
| |
| #include <linux/cpu.h> |
| #include <linux/cpumask.h> |
| #include <linux/cpuset.h> |
| #include <linux/err.h> |
| #include <linux/errno.h> |
| #include <linux/file.h> |
| #include <linux/fs.h> |
| #include <linux/init.h> |
| #include <linux/interrupt.h> |
| #include <linux/kernel.h> |
| #include <linux/kmod.h> |
| #include <linux/list.h> |
| #include <linux/mempolicy.h> |
| #include <linux/mm.h> |
| #include <linux/memory.h> |
| #include <linux/export.h> |
| #include <linux/mount.h> |
| #include <linux/fs_context.h> |
| #include <linux/namei.h> |
| #include <linux/pagemap.h> |
| #include <linux/proc_fs.h> |
| #include <linux/rcupdate.h> |
| #include <linux/sched.h> |
| #include <linux/sched/mm.h> |
| #include <linux/sched/task.h> |
| #include <linux/seq_file.h> |
| #include <linux/security.h> |
| #include <linux/slab.h> |
| #include <linux/spinlock.h> |
| #include <linux/stat.h> |
| #include <linux/string.h> |
| #include <linux/time.h> |
| #include <linux/time64.h> |
| #include <linux/backing-dev.h> |
| #include <linux/sort.h> |
| #include <linux/oom.h> |
| #include <linux/sched/isolation.h> |
| #include <linux/uaccess.h> |
| #include <linux/atomic.h> |
| #include <linux/mutex.h> |
| #include <linux/cgroup.h> |
| #include <linux/wait.h> |
| |
| DEFINE_STATIC_KEY_FALSE(cpusets_pre_enable_key); |
| DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key); |
| |
| /* See "Frequency meter" comments, below. */ |
| |
| struct fmeter { |
| int cnt; /* unprocessed events count */ |
| int val; /* most recent output value */ |
| time64_t time; /* clock (secs) when val computed */ |
| spinlock_t lock; /* guards read or write of above */ |
| }; |
| |
| struct cpuset { |
| struct cgroup_subsys_state css; |
| |
| unsigned long flags; /* "unsigned long" so bitops work */ |
| |
| /* |
| * On default hierarchy: |
| * |
| * The user-configured masks can only be changed by writing to |
| * cpuset.cpus and cpuset.mems, and won't be limited by the |
| * parent masks. |
| * |
| * The effective masks is the real masks that apply to the tasks |
| * in the cpuset. They may be changed if the configured masks are |
| * changed or hotplug happens. |
| * |
| * effective_mask == configured_mask & parent's effective_mask, |
| * and if it ends up empty, it will inherit the parent's mask. |
| * |
| * |
| * On legacy hierachy: |
| * |
| * The user-configured masks are always the same with effective masks. |
| */ |
| |
| /* user-configured CPUs and Memory Nodes allow to tasks */ |
| cpumask_var_t cpus_allowed; |
| nodemask_t mems_allowed; |
| |
| /* effective CPUs and Memory Nodes allow to tasks */ |
| cpumask_var_t effective_cpus; |
| nodemask_t effective_mems; |
| |
| /* |
| * CPUs allocated to child sub-partitions (default hierarchy only) |
| * - CPUs granted by the parent = effective_cpus U subparts_cpus |
| * - effective_cpus and subparts_cpus are mutually exclusive. |
| * |
| * effective_cpus contains only onlined CPUs, but subparts_cpus |
| * may have offlined ones. |
| */ |
| cpumask_var_t subparts_cpus; |
| |
| /* |
| * This is old Memory Nodes tasks took on. |
| * |
| * - top_cpuset.old_mems_allowed is initialized to mems_allowed. |
| * - A new cpuset's old_mems_allowed is initialized when some |
| * task is moved into it. |
| * - old_mems_allowed is used in cpuset_migrate_mm() when we change |
| * cpuset.mems_allowed and have tasks' nodemask updated, and |
| * then old_mems_allowed is updated to mems_allowed. |
| */ |
| nodemask_t old_mems_allowed; |
| |
| struct fmeter fmeter; /* memory_pressure filter */ |
| |
| /* |
| * Tasks are being attached to this cpuset. Used to prevent |
| * zeroing cpus/mems_allowed between ->can_attach() and ->attach(). |
| */ |
| int attach_in_progress; |
| |
| /* partition number for rebuild_sched_domains() */ |
| int pn; |
| |
| /* for custom sched domain */ |
| int relax_domain_level; |
| |
| /* number of CPUs in subparts_cpus */ |
| int nr_subparts_cpus; |
| |
| /* partition root state */ |
| int partition_root_state; |
| |
| /* |
| * Default hierarchy only: |
| * use_parent_ecpus - set if using parent's effective_cpus |
| * child_ecpus_count - # of children with use_parent_ecpus set |
| */ |
| int use_parent_ecpus; |
| int child_ecpus_count; |
| }; |
| |
| /* |
| * Partition root states: |
| * |
| * 0 - not a partition root |
| * |
| * 1 - partition root |
| * |
| * -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. |
| */ |
| #define PRS_DISABLED 0 |
| #define PRS_ENABLED 1 |
| #define PRS_ERROR -1 |
| |
| /* |
| * Temporary cpumasks for working with partitions that are passed among |
| * functions to avoid memory allocation in inner functions. |
| */ |
| struct tmpmasks { |
| cpumask_var_t addmask, delmask; /* For partition root */ |
| cpumask_var_t new_cpus; /* For update_cpumasks_hier() */ |
| }; |
| |
| static inline struct cpuset *css_cs(struct cgroup_subsys_state *css) |
| { |
| return css ? container_of(css, struct cpuset, css) : NULL; |
| } |
| |
| /* Retrieve the cpuset for a task */ |
| static inline struct cpuset *task_cs(struct task_struct *task) |
| { |
| return css_cs(task_css(task, cpuset_cgrp_id)); |
| } |
| |
| static inline struct cpuset *parent_cs(struct cpuset *cs) |
| { |
| return css_cs(cs->css.parent); |
| } |
| |
| /* bits in struct cpuset flags field */ |
| typedef enum { |
| CS_ONLINE, |
| CS_CPU_EXCLUSIVE, |
| CS_MEM_EXCLUSIVE, |
| CS_MEM_HARDWALL, |
| CS_MEMORY_MIGRATE, |
| CS_SCHED_LOAD_BALANCE, |
| CS_SPREAD_PAGE, |
| CS_SPREAD_SLAB, |
| } cpuset_flagbits_t; |
| |
| /* convenient tests for these bits */ |
| static inline bool is_cpuset_online(struct cpuset *cs) |
| { |
| return test_bit(CS_ONLINE, &cs->flags) && !css_is_dying(&cs->css); |
| } |
| |
| static inline int is_cpu_exclusive(const struct cpuset *cs) |
| { |
| return test_bit(CS_CPU_EXCLUSIVE, &cs->flags); |
| } |
| |
| static inline int is_mem_exclusive(const struct cpuset *cs) |
| { |
| return test_bit(CS_MEM_EXCLUSIVE, &cs->flags); |
| } |
| |
| static inline int is_mem_hardwall(const struct cpuset *cs) |
| { |
| return test_bit(CS_MEM_HARDWALL, &cs->flags); |
| } |
| |
| static inline int is_sched_load_balance(const struct cpuset *cs) |
| { |
| return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags); |
| } |
| |
| static inline int is_memory_migrate(const struct cpuset *cs) |
| { |
| return test_bit(CS_MEMORY_MIGRATE, &cs->flags); |
| } |
| |
| static inline int is_spread_page(const struct cpuset *cs) |
| { |
| return test_bit(CS_SPREAD_PAGE, &cs->flags); |
| } |
| |
| 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) |
| { |
| return cs->partition_root_state > 0; |
| } |
| |
| static struct cpuset top_cpuset = { |
| .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) | |
| (1 << CS_MEM_EXCLUSIVE)), |
| .partition_root_state = PRS_ENABLED, |
| }; |
| |
| /** |
| * cpuset_for_each_child - traverse online children of a cpuset |
| * @child_cs: loop cursor pointing to the current child |
| * @pos_css: used for iteration |
| * @parent_cs: target cpuset to walk children of |
| * |
| * Walk @child_cs through the online children of @parent_cs. Must be used |
| * with RCU read locked. |
| */ |
| #define cpuset_for_each_child(child_cs, pos_css, parent_cs) \ |
| css_for_each_child((pos_css), &(parent_cs)->css) \ |
| if (is_cpuset_online(((child_cs) = css_cs((pos_css))))) |
| |
| /** |
| * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants |
| * @des_cs: loop cursor pointing to the current descendant |
| * @pos_css: used for iteration |
| * @root_cs: target cpuset to walk ancestor of |
| * |
| * Walk @des_cs through the online descendants of @root_cs. Must be used |
| * with RCU read locked. The caller may modify @pos_css by calling |
| * css_rightmost_descendant() to skip subtree. @root_cs is included in the |
| * iteration and the first node to be visited. |
| */ |
| #define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs) \ |
| css_for_each_descendant_pre((pos_css), &(root_cs)->css) \ |
| if (is_cpuset_online(((des_cs) = css_cs((pos_css))))) |
| |
| /* |
| * There are two global locks guarding cpuset structures - cpuset_mutex 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. |
| * |
| * 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 |
| * 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 |
| * 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. |
| * |
| * Calls to the kernel memory allocator can not be made while holding |
| * callback_lock, as that would risk double tripping on callback_lock |
| * from one of the callbacks into the cpuset code from within |
| * __alloc_pages(). |
| * |
| * If a task is only holding callback_lock, then it has read-only |
| * access to cpusets. |
| * |
| * Now, the task_struct fields mems_allowed and mempolicy may be changed |
| * by other task, we use alloc_lock in the task_struct fields to protect |
| * them. |
| * |
| * The cpuset_common_file_read() handlers only hold callback_lock across |
| * small pieces of code, such as when reading out possibly multi-word |
| * cpumasks and nodemasks. |
| * |
| * Accessing a task's cpuset should be done in accordance with the |
| * guidelines for accessing subsystem state in kernel/cgroup.c |
| */ |
| |
| static DEFINE_MUTEX(cpuset_mutex); |
| static DEFINE_SPINLOCK(callback_lock); |
| |
| static struct workqueue_struct *cpuset_migrate_mm_wq; |
| |
| /* |
| * CPU / memory hotplug is handled asynchronously. |
| */ |
| static void cpuset_hotplug_workfn(struct work_struct *work); |
| static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn); |
| |
| static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq); |
| |
| /* |
| * Cgroup v2 behavior is used when on default hierarchy or the |
| * cgroup_v2_mode flag is set. |
| */ |
| static inline bool is_in_v2_mode(void) |
| { |
| return cgroup_subsys_on_dfl(cpuset_cgrp_subsys) || |
| (cpuset_cgrp_subsys.root->flags & CGRP_ROOT_CPUSET_V2_MODE); |
| } |
| |
| /* |
| * 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. |
| * |
| * One way or another, we guarantee to return some non-empty subset |
| * of cpu_online_mask. |
| * |
| * Call with callback_lock or cpuset_mutex held. |
| */ |
| static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask) |
| { |
| while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) { |
| 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 |
| * identical to cpu_online_mask. |
| */ |
| cpumask_copy(pmask, cpu_online_mask); |
| return; |
| } |
| } |
| cpumask_and(pmask, cs->effective_cpus, cpu_online_mask); |
| } |
| |
| /* |
| * Return in *pmask the portion of a cpusets's mems_allowed that |
| * are online, with memory. If none are online with memory, walk |
| * up the cpuset hierarchy until we find one that does have some |
| * online mems. The top cpuset always has some mems online. |
| * |
| * 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. |
| */ |
| static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask) |
| { |
| while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY])) |
| cs = parent_cs(cs); |
| nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]); |
| } |
| |
| /* |
| * update task's spread flag if cpuset's page/slab spread flag is set |
| * |
| * Call with callback_lock or cpuset_mutex held. |
| */ |
| static void cpuset_update_task_spread_flag(struct cpuset *cs, |
| struct task_struct *tsk) |
| { |
| if (is_spread_page(cs)) |
| task_set_spread_page(tsk); |
| else |
| task_clear_spread_page(tsk); |
| |
| if (is_spread_slab(cs)) |
| task_set_spread_slab(tsk); |
| else |
| task_clear_spread_slab(tsk); |
| } |
| |
| /* |
| * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q? |
| * |
| * 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. |
| */ |
| |
| static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q) |
| { |
| return cpumask_subset(p->cpus_allowed, q->cpus_allowed) && |
| nodes_subset(p->mems_allowed, q->mems_allowed) && |
| is_cpu_exclusive(p) <= is_cpu_exclusive(q) && |
| is_mem_exclusive(p) <= is_mem_exclusive(q); |
| } |
| |
| /** |
| * alloc_cpumasks - allocate three cpumasks for cpuset |
| * @cs: the cpuset that have cpumasks to be allocated. |
| * @tmp: the tmpmasks structure pointer |
| * Return: 0 if successful, -ENOMEM otherwise. |
| * |
| * Only one of the two input arguments should be non-NULL. |
| */ |
| static inline int alloc_cpumasks(struct cpuset *cs, struct tmpmasks *tmp) |
| { |
| cpumask_var_t *pmask1, *pmask2, *pmask3; |
| |
| if (cs) { |
| pmask1 = &cs->cpus_allowed; |
| pmask2 = &cs->effective_cpus; |
| pmask3 = &cs->subparts_cpus; |
| } else { |
| pmask1 = &tmp->new_cpus; |
| pmask2 = &tmp->addmask; |
| pmask3 = &tmp->delmask; |
| } |
| |
| if (!zalloc_cpumask_var(pmask1, GFP_KERNEL)) |
| return -ENOMEM; |
| |
| if (!zalloc_cpumask_var(pmask2, GFP_KERNEL)) |
| goto free_one; |
| |
| if (!zalloc_cpumask_var(pmask3, GFP_KERNEL)) |
| goto free_two; |
| |
| return 0; |
| |
| free_two: |
| free_cpumask_var(*pmask2); |
| free_one: |
| free_cpumask_var(*pmask1); |
| return -ENOMEM; |
| } |
| |
| /** |
| * free_cpumasks - free cpumasks in a tmpmasks structure |
| * @cs: the cpuset that have cpumasks to be free. |
| * @tmp: the tmpmasks structure pointer |
| */ |
| static inline void free_cpumasks(struct cpuset *cs, struct tmpmasks *tmp) |
| { |
| if (cs) { |
| free_cpumask_var(cs->cpus_allowed); |
| free_cpumask_var(cs->effective_cpus); |
| free_cpumask_var(cs->subparts_cpus); |
| } |
| if (tmp) { |
| free_cpumask_var(tmp->new_cpus); |
| free_cpumask_var(tmp->addmask); |
| free_cpumask_var(tmp->delmask); |
| } |
| } |
| |
| /** |
| * alloc_trial_cpuset - allocate a trial cpuset |
| * @cs: the cpuset that the trial cpuset duplicates |
| */ |
| static struct cpuset *alloc_trial_cpuset(struct cpuset *cs) |
| { |
| struct cpuset *trial; |
| |
| trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL); |
| if (!trial) |
| return NULL; |
| |
| if (alloc_cpumasks(trial, NULL)) { |
| kfree(trial); |
| return NULL; |
| } |
| |
| cpumask_copy(trial->cpus_allowed, cs->cpus_allowed); |
| cpumask_copy(trial->effective_cpus, cs->effective_cpus); |
| return trial; |
| } |
| |
| /** |
| * free_cpuset - free the cpuset |
| * @cs: the cpuset to be freed |
| */ |
| static inline void free_cpuset(struct cpuset *cs) |
| { |
| free_cpumasks(cs, NULL); |
| kfree(cs); |
| } |
| |
| /* |
| * 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. |
| * |
| * 'cur' is the address of an actual, in-use cpuset. Operations |
| * such as list traversal that depend on the actual address of the |
| * cpuset in the list must use cur below, not trial. |
| * |
| * 'trial' is the address of bulk structure copy of cur, with |
| * perhaps one or more of the fields cpus_allowed, mems_allowed, |
| * or flags changed to new, trial values. |
| * |
| * Return 0 if valid, -errno if not. |
| */ |
| |
| static int validate_change(struct cpuset *cur, struct cpuset *trial) |
| { |
| struct cgroup_subsys_state *css; |
| struct cpuset *c, *par; |
| int ret; |
| |
| 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; |
| |
| /* 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. |
| */ |
| ret = -ENOSPC; |
| if ((cgroup_is_populated(cur->css.cgroup) || cur->attach_in_progress)) { |
| if (!cpumask_empty(cur->cpus_allowed) && |
| cpumask_empty(trial->cpus_allowed)) |
| goto out; |
| if (!nodes_empty(cur->mems_allowed) && |
| nodes_empty(trial->mems_allowed)) |
| goto out; |
| } |
| |
| /* |
| * We can't shrink if we won't have enough room for SCHED_DEADLINE |
| * tasks. |
| */ |
| ret = -EBUSY; |
| if (is_cpu_exclusive(cur) && |
| !cpuset_cpumask_can_shrink(cur->cpus_allowed, |
| trial->cpus_allowed)) |
| goto out; |
| |
| ret = 0; |
| out: |
| rcu_read_unlock(); |
| return ret; |
| } |
| |
| #ifdef CONFIG_SMP |
| /* |
| * Helper routine for generate_sched_domains(). |
| * Do cpusets a, b have overlapping effective cpus_allowed masks? |
| */ |
| static int cpusets_overlap(struct cpuset *a, struct cpuset *b) |
| { |
| return cpumask_intersects(a->effective_cpus, b->effective_cpus); |
| } |
| |
| static void |
| update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c) |
| { |
| if (dattr->relax_domain_level < c->relax_domain_level) |
| dattr->relax_domain_level = c->relax_domain_level; |
| return; |
| } |
| |
| static void update_domain_attr_tree(struct sched_domain_attr *dattr, |
| struct cpuset *root_cs) |
| { |
| struct cpuset *cp; |
| struct cgroup_subsys_state *pos_css; |
| |
| rcu_read_lock(); |
| cpuset_for_each_descendant_pre(cp, pos_css, root_cs) { |
| /* skip the whole subtree if @cp doesn't have any CPU */ |
| if (cpumask_empty(cp->cpus_allowed)) { |
| pos_css = css_rightmost_descendant(pos_css); |
| continue; |
| } |
| |
| if (is_sched_load_balance(cp)) |
| update_domain_attr(dattr, cp); |
| } |
| rcu_read_unlock(); |
| } |
| |
| /* Must be called with cpuset_mutex held. */ |
| static inline int nr_cpusets(void) |
| { |
| /* jump label reference count + the top-level cpuset */ |
| return static_key_count(&cpusets_enabled_key.key) + 1; |
| } |
| |
| /* |
| * generate_sched_domains() |
| * |
| * This function builds a partial partition of the systems CPUs |
| * A 'partial partition' is a set of non-overlapping subsets whose |
| * union is a subset of that set. |
| * The output of this function needs to be passed to kernel/sched/core.c |
| * partition_sched_domains() routine, which will rebuild the scheduler's |
| * load balancing domains (sched domains) as specified by that partial |
| * partition. |
| * |
| * See "What is sched_load_balance" in Documentation/admin-guide/cgroup-v1/cpusets.rst |
| * for a background explanation of this. |
| * |
| * Does not return errors, on the theory that the callers of this |
| * routine would rather not worry about failures to rebuild sched |
| * domains when operating in the severe memory shortage situations |
| * that could cause allocation failures below. |
| * |
| * Must be called with cpuset_mutex held. |
| * |
| * The three key local variables below are: |
| * cp - cpuset pointer, used (together with pos_css) to perform a |
| * top-down scan of all cpusets. For our purposes, rebuilding |
| * the schedulers sched domains, we can ignore !is_sched_load_ |
| * balance cpusets. |
| * csa - (for CpuSet Array) Array of pointers to all the cpusets |
| * that need to be load balanced, for convenient iterative |
| * access by the subsequent code that finds the best partition, |
| * i.e the set of domains (subsets) of CPUs such that the |
| * cpus_allowed of every cpuset marked is_sched_load_balance |
| * is a subset of one of these domains, while there are as |
| * many such domains as possible, each as small as possible. |
| * doms - Conversion of 'csa' to an array of cpumasks, for passing to |
| * the kernel/sched/core.c routine partition_sched_domains() in a |
| * convenient format, that can be easily compared to the prior |
| * value to determine what partition elements (sched domains) |
| * were changed (added or removed.) |
| * |
| * Finding the best partition (set of domains): |
| * The triple nested loops below over i, j, k scan over the |
| * load balanced cpusets (using the array of cpuset pointers in |
| * csa[]) looking for pairs of cpusets that have overlapping |
| * cpus_allowed, but which don't have the same 'pn' partition |
| * number and gives them in the same partition number. It keeps |
| * looping on the 'restart' label until it can no longer find |
| * any such pairs. |
| * |
| * The union of the cpus_allowed masks from the set of |
| * all cpusets having the same 'pn' value then form the one |
| * element of the partition (one sched domain) to be passed to |
| * partition_sched_domains(). |
| */ |
| static int generate_sched_domains(cpumask_var_t **domains, |
| struct sched_domain_attr **attributes) |
| { |
| struct cpuset *cp; /* top-down scan of cpusets */ |
| struct cpuset **csa; /* array of all cpuset ptrs */ |
| int csn; /* how many cpuset ptrs in csa so far */ |
| int i, j, k; /* indices for partition finding loops */ |
| cpumask_var_t *doms; /* resulting partition; i.e. sched domains */ |
| struct sched_domain_attr *dattr; /* attributes for custom domains */ |
| int ndoms = 0; /* number of sched domains in result */ |
| int nslot; /* next empty doms[] struct cpumask slot */ |
| struct cgroup_subsys_state *pos_css; |
| bool root_load_balance = is_sched_load_balance(&top_cpuset); |
| |
| doms = NULL; |
| dattr = NULL; |
| csa = NULL; |
| |
| /* Special case for the 99% of systems with one, full, sched domain */ |
| if (root_load_balance && !top_cpuset.nr_subparts_cpus) { |
| ndoms = 1; |
| doms = alloc_sched_domains(ndoms); |
| if (!doms) |
| goto done; |
| |
| dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL); |
| if (dattr) { |
| *dattr = SD_ATTR_INIT; |
| update_domain_attr_tree(dattr, &top_cpuset); |
| } |
| cpumask_and(doms[0], top_cpuset.effective_cpus, |
| housekeeping_cpumask(HK_FLAG_DOMAIN)); |
| |
| goto done; |
| } |
| |
| csa = kmalloc_array(nr_cpusets(), sizeof(cp), GFP_KERNEL); |
| if (!csa) |
| goto done; |
| csn = 0; |
| |
| rcu_read_lock(); |
| if (root_load_balance) |
| csa[csn++] = &top_cpuset; |
| cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) { |
| if (cp == &top_cpuset) |
| continue; |
| /* |
| * Continue traversing beyond @cp iff @cp has some CPUs and |
| * isn't load balancing. The former is obvious. The |
| * latter: All child cpusets contain a subset of the |
| * parent's cpus, so just skip them, and then we call |
| * update_domain_attr_tree() to calc relax_domain_level of |
| * the corresponding sched domain. |
| * |
| * If root is load-balancing, we can skip @cp if it |
| * is a subset of the root's effective_cpus. |
| */ |
| if (!cpumask_empty(cp->cpus_allowed) && |
| !(is_sched_load_balance(cp) && |
| cpumask_intersects(cp->cpus_allowed, |
| housekeeping_cpumask(HK_FLAG_DOMAIN)))) |
| continue; |
| |
| if (root_load_balance && |
| cpumask_subset(cp->cpus_allowed, top_cpuset.effective_cpus)) |
| continue; |
| |
| if (is_sched_load_balance(cp)) |
| csa[csn++] = cp; |
| |
| /* skip @cp's subtree if not a partition root */ |
| if (!is_partition_root(cp)) |
| pos_css = css_rightmost_descendant(pos_css); |
| } |
| rcu_read_unlock(); |
| |
| for (i = 0; i < csn; i++) |
| csa[i]->pn = i; |
| ndoms = csn; |
| |
| restart: |
| /* Find the best partition (set of sched domains) */ |
| for (i = 0; i < csn; i++) { |
| struct cpuset *a = csa[i]; |
| int apn = a->pn; |
| |
| for (j = 0; j < csn; j++) { |
| struct cpuset *b = csa[j]; |
| int bpn = b->pn; |
| |
| if (apn != bpn && cpusets_overlap(a, b)) { |
| for (k = 0; k < csn; k++) { |
| struct cpuset *c = csa[k]; |
| |
| if (c->pn == bpn) |
| c->pn = apn; |
| } |
| ndoms--; /* one less element */ |
| goto restart; |
| } |
| } |
| } |
| |
| /* |
| * Now we know how many domains to create. |
| * Convert <csn, csa> to <ndoms, doms> and populate cpu masks. |
| */ |
| doms = alloc_sched_domains(ndoms); |
| if (!doms) |
| goto done; |
| |
| /* |
| * The rest of the code, including the scheduler, can deal with |
| * dattr==NULL case. No need to abort if alloc fails. |
| */ |
| dattr = kmalloc_array(ndoms, sizeof(struct sched_domain_attr), |
| GFP_KERNEL); |
| |
| for (nslot = 0, i = 0; i < csn; i++) { |
| struct cpuset *a = csa[i]; |
| struct cpumask *dp; |
| int apn = a->pn; |
| |
| if (apn < 0) { |
| /* Skip completed partitions */ |
| continue; |
| } |
| |
| dp = doms[nslot]; |
| |
| if (nslot == ndoms) { |
| static int warnings = 10; |
| if (warnings) { |
| pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n", |
| nslot, ndoms, csn, i, apn); |
| warnings--; |
| } |
| continue; |
| } |
| |
| cpumask_clear(dp); |
| if (dattr) |
| *(dattr + nslot) = SD_ATTR_INIT; |
| for (j = i; j < csn; j++) { |
| struct cpuset *b = csa[j]; |
| |
| if (apn == b->pn) { |
| cpumask_or(dp, dp, b->effective_cpus); |
| cpumask_and(dp, dp, housekeeping_cpumask(HK_FLAG_DOMAIN)); |
| if (dattr) |
| update_domain_attr_tree(dattr + nslot, b); |
| |
| /* Done with this partition */ |
| b->pn = -1; |
| } |
| } |
| nslot++; |
| } |
| BUG_ON(nslot != ndoms); |
| |
| done: |
| kfree(csa); |
| |
| /* |
| * Fallback to the default domain if kmalloc() failed. |
| * See comments in partition_sched_domains(). |
| */ |
| if (doms == NULL) |
| ndoms = 1; |
| |
| *domains = doms; |
| *attributes = dattr; |
| return ndoms; |
| } |
| |
| /* |
| * Rebuild scheduler domains. |
| * |
| * If the flag 'sched_load_balance' of any cpuset with non-empty |
| * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset |
| * which has that flag enabled, or if any cpuset with a non-empty |
| * 'cpus' is removed, then call this routine to rebuild the |
| * scheduler's dynamic sched domains. |
| * |
| * Call with cpuset_mutex held. Takes get_online_cpus(). |
| */ |
| static void rebuild_sched_domains_locked(void) |
| { |
| struct sched_domain_attr *attr; |
| cpumask_var_t *doms; |
| int ndoms; |
| |
| lockdep_assert_held(&cpuset_mutex); |
| get_online_cpus(); |
| |
| /* |
| * We have raced with CPU hotplug. Don't do anything to avoid |
| * passing doms with offlined cpu to partition_sched_domains(). |
| * Anyways, hotplug work item will rebuild sched domains. |
| */ |
| if (!top_cpuset.nr_subparts_cpus && |
| !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) |
| goto out; |
| |
| if (top_cpuset.nr_subparts_cpus && |
| !cpumask_subset(top_cpuset.effective_cpus, cpu_active_mask)) |
| goto out; |
| |
| /* 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) |
| { |
| } |
| #endif /* CONFIG_SMP */ |
| |
| void rebuild_sched_domains(void) |
| { |
| mutex_lock(&cpuset_mutex); |
| rebuild_sched_domains_locked(); |
| mutex_unlock(&cpuset_mutex); |
| } |
| |
| /** |
| * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset. |
| * @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, |
| * cpuset membership stays stable. |
| */ |
| static void update_tasks_cpumask(struct cpuset *cs) |
| { |
| struct css_task_iter it; |
| struct task_struct *task; |
| |
| css_task_iter_start(&cs->css, 0, &it); |
| while ((task = css_task_iter_next(&it))) |
| set_cpus_allowed_ptr(task, cs->effective_cpus); |
| css_task_iter_end(&it); |
| } |
| |
| /** |
| * compute_effective_cpumask - Compute the effective cpumask of the cpuset |
| * @new_cpus: the temp variable for the new effective_cpus mask |
| * @cs: the cpuset the need to recompute the new effective_cpus mask |
| * @parent: the parent cpuset |
| * |
| * If the parent has subpartition CPUs, include them in the list of |
| * allowable CPUs in computing the new effective_cpus mask. Since offlined |
| * CPUs are not removed from subparts_cpus, we have to use cpu_active_mask |
| * to mask those out. |
| */ |
| static void compute_effective_cpumask(struct cpumask *new_cpus, |
| struct cpuset *cs, struct cpuset *parent) |
| { |
| if (parent->nr_subparts_cpus) { |
| cpumask_or(new_cpus, parent->effective_cpus, |
| parent->subparts_cpus); |
| cpumask_and(new_cpus, new_cpus, cs->cpus_allowed); |
| cpumask_and(new_cpus, new_cpus, cpu_active_mask); |
| } else { |
| cpumask_and(new_cpus, cs->cpus_allowed, parent->effective_cpus); |
| } |
| } |
| |
| /* |
| * Commands for update_parent_subparts_cpumask |
| */ |
| enum subparts_cmd { |
| partcmd_enable, /* Enable partition root */ |
| partcmd_disable, /* Disable partition root */ |
| partcmd_update, /* Update parent's subparts_cpus */ |
| }; |
| |
| /** |
| * 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 |
| * |
| * 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 |
| * be put into parent's subparts_cpus and taken away from parent's |
| * 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 |
| * parent's subparts_cpus will be taken away from that cpumask and put back |
| * into parent's effective_cpus. 0 should 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 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. |
| * |
| * 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. |
| */ |
| static int update_parent_subparts_cpumask(struct cpuset *cpuset, int cmd, |
| struct cpumask *newmask, |
| struct tmpmasks *tmp) |
| { |
| struct cpuset *parent = parent_cs(cpuset); |
| 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? */ |
| |
| lockdep_assert_held(&cpuset_mutex); |
| |
| /* |
| * The parent must be a partition root. |
| * 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; |
| |
| /* |
| * A cpumask update cannot make parent's effective_cpus become empty. |
| */ |
| adding = deleting = false; |
| if (cmd == partcmd_enable) { |
| cpumask_copy(tmp->addmask, cpuset->cpus_allowed); |
| adding = true; |
| } else if (cmd == partcmd_disable) { |
| deleting = cpumask_and(tmp->delmask, cpuset->cpus_allowed, |
| parent->subparts_cpus); |
| } else if (newmask) { |
| /* |
| * partcmd_update with newmask: |
| * |
| * delmask = cpus_allowed & ~newmask & parent->subparts_cpus |
| * addmask = newmask & parent->effective_cpus |
| * & ~parent->subparts_cpus |
| */ |
| cpumask_andnot(tmp->delmask, cpuset->cpus_allowed, newmask); |
| deleting = cpumask_and(tmp->delmask, tmp->delmask, |
| parent->subparts_cpus); |
| |
| cpumask_and(tmp->addmask, newmask, parent->effective_cpus); |
| adding = cpumask_andnot(tmp->addmask, tmp->addmask, |
| parent->subparts_cpus); |
| /* |
| * Return error if the new effective_cpus could become empty. |
| */ |
| 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); |
| } |
| } else { |
| /* |
| * partcmd_update w/o newmask: |
| * |
| * addmask = cpus_allowed & parent->effectiveb_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. |
| */ |
| adding = cpumask_and(tmp->addmask, cpuset->cpus_allowed, |
| parent->effective_cpus); |
| part_error = cpumask_equal(tmp->addmask, |
| parent->effective_cpus); |
| } |
| |
| if (cmd == partcmd_update) { |
| int prev_prs = cpuset->partition_root_state; |
| |
| /* |
| * Check for possible transition between PRS_ENABLED |
| * and PRS_ERROR. |
| */ |
| switch (cpuset->partition_root_state) { |
| case PRS_ENABLED: |
| if (part_error) |
| cpuset->partition_root_state = PRS_ERROR; |
| break; |
| case PRS_ERROR: |
| if (!part_error) |
| cpuset->partition_root_state = PRS_ENABLED; |
| 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 (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); |
| } |
| |
| if (!adding && !deleting) |
| return 0; |
| |
| /* |
| * Change the parent's subparts_cpus. |
| * Newly added CPUs will be removed from effective_cpus and |
| * newly deleted ones will be added back to effective_cpus. |
| */ |
| spin_lock_irq(&callback_lock); |
| if (adding) { |
| cpumask_or(parent->subparts_cpus, |
| parent->subparts_cpus, tmp->addmask); |
| cpumask_andnot(parent->effective_cpus, |
| parent->effective_cpus, tmp->addmask); |
| } |
| if (deleting) { |
| cpumask_andnot(parent->subparts_cpus, |
| parent->subparts_cpus, tmp->delmask); |
| /* |
| * Some of the CPUs in subparts_cpus might have been offlined. |
| */ |
| cpumask_and(tmp->delmask, tmp->delmask, cpu_active_mask); |
| cpumask_or(parent->effective_cpus, |
| parent->effective_cpus, tmp->delmask); |
| } |
| |
| parent->nr_subparts_cpus = cpumask_weight(parent->subparts_cpus); |
| spin_unlock_irq(&callback_lock); |
| |
| return cmd == partcmd_update; |
| } |
| |
| /* |
| * 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 |
| * |
| * When congifured 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. |
| * |
| * Called with cpuset_mutex held |
| */ |
| static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp) |
| { |
| struct cpuset *cp; |
| struct cgroup_subsys_state *pos_css; |
| bool need_rebuild_sched_domains = false; |
| |
| rcu_read_lock(); |
| cpuset_for_each_descendant_pre(cp, pos_css, cs) { |
| struct cpuset *parent = parent_cs(cp); |
| |
| 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. |
| */ |
| if (is_in_v2_mode() && cpumask_empty(tmp->new_cpus)) { |
| cpumask_copy(tmp->new_cpus, parent->effective_cpus); |
| if (!cp->use_parent_ecpus) { |
| cp->use_parent_ecpus = true; |
| parent->child_ecpus_count++; |
| } |
| } else if (cp->use_parent_ecpus) { |
| cp->use_parent_ecpus = false; |
| WARN_ON_ONCE(!parent->child_ecpus_count); |
| parent->child_ecpus_count--; |
| } |
| |
| /* |
| * Skip the whole subtree if the cpumask remains the same |
| * and has no partition root state. |
| */ |
| if (!cp->partition_root_state && |
| cpumask_equal(tmp->new_cpus, cp->effective_cpus)) { |
| pos_css = css_rightmost_descendant(pos_css); |
| continue; |
| } |
| |
| /* |
| * 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) { |
| 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); |
| break; |
| |
| case PRS_ERROR: |
| /* |
| * When parent is invalid, it has to be too. |
| */ |
| cp->partition_root_state = PRS_ERROR; |
| if (cp->nr_subparts_cpus) { |
| cp->nr_subparts_cpus = 0; |
| cpumask_clear(cp->subparts_cpus); |
| } |
| break; |
| } |
| } |
| |
| if (!css_tryget_online(&cp->css)) |
| continue; |
| rcu_read_unlock(); |
| |
| spin_lock_irq(&callback_lock); |
| |
| cpumask_copy(cp->effective_cpus, tmp->new_cpus); |
| if (cp->nr_subparts_cpus && |
| (cp->partition_root_state != PRS_ENABLED)) { |
| cp->nr_subparts_cpus = 0; |
| cpumask_clear(cp->subparts_cpus); |
| } else 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); |
| } |
| } |
| spin_unlock_irq(&callback_lock); |
| |
| WARN_ON(!is_in_v2_mode() && |
| !cpumask_equal(cp->cpus_allowed, cp->effective_cpus)); |
| |
| update_tasks_cpumask(cp); |
| |
| /* |
| * On legacy hierarchy, if the effective cpumask of any non- |
| * empty cpuset is changed, we need to rebuild sched domains. |
| * On default hierarchy, the cpuset needs to be a partition |
| * root as well. |
| */ |
| if (!cpumask_empty(cp->cpus_allowed) && |
| is_sched_load_balance(cp) && |
| (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) || |
| is_partition_root(cp))) |
| need_rebuild_sched_domains = true; |
| |
| rcu_read_lock(); |
| css_put(&cp->css); |
| } |
| rcu_read_unlock(); |
| |
| if (need_rebuild_sched_domains) |
| rebuild_sched_domains_locked(); |
| } |
| |
| /** |
| * update_sibling_cpumasks - Update siblings cpumasks |
| * @parent: Parent cpuset |
| * @cs: Current cpuset |
| * @tmp: Temp variables |
| */ |
| static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs, |
| struct tmpmasks *tmp) |
| { |
| struct cpuset *sibling; |
| struct cgroup_subsys_state *pos_css; |
| |
| /* |
| * 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. |
| */ |
| rcu_read_lock(); |
| cpuset_for_each_child(sibling, pos_css, parent) { |
| if (sibling == cs) |
| continue; |
| if (!sibling->use_parent_ecpus) |
| continue; |
| |
| update_cpumasks_hier(sibling, tmp); |
| } |
| rcu_read_unlock(); |
| } |
| |
| /** |
| * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it |
| * @cs: the cpuset to consider |
| * @trialcs: trial cpuset |
| * @buf: buffer of cpu numbers written to this cpuset |
| */ |
| static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, |
| const char *buf) |
| { |
| int retval; |
| struct tmpmasks tmp; |
| |
| /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */ |
| if (cs == &top_cpuset) |
| return -EACCES; |
| |
| /* |
| * An empty cpus_allowed is ok only if the cpuset has no tasks. |
| * Since cpulist_parse() fails on an empty mask, we special case |
| * that parsing. The validate_change() call ensures that cpusets |
| * with tasks have cpus. |
| */ |
| if (!*buf) { |
| cpumask_clear(trialcs->cpus_allowed); |
| } else { |
| retval = cpulist_parse(buf, trialcs->cpus_allowed); |
| if (retval < 0) |
| return retval; |
| |
| if (!cpumask_subset(trialcs->cpus_allowed, |
| top_cpuset.cpus_allowed)) |
| return -EINVAL; |
| } |
| |
| /* Nothing to do if the cpus didn't change */ |
| 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 |
| * to allocated cpumasks. |
| */ |
| tmp.addmask = trialcs->subparts_cpus; |
| tmp.delmask = trialcs->effective_cpus; |
| tmp.new_cpus = trialcs->cpus_allowed; |
| #endif |
| |
| 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; |
| } |
| |
| spin_lock_irq(&callback_lock); |
| cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed); |
| |
| /* |
| * Make sure that subparts_cpus is a subset of cpus_allowed. |
| */ |
| 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); |
| } |
| spin_unlock_irq(&callback_lock); |
| |
| update_cpumasks_hier(cs, &tmp); |
| |
| if (cs->partition_root_state) { |
| struct cpuset *parent = parent_cs(cs); |
| |
| /* |
| * For partition root, update the cpumasks of sibling |
| * cpusets if they use parent's effective_cpus. |
| */ |
| if (parent->child_ecpus_count) |
| update_sibling_cpumasks(parent, cs, &tmp); |
| } |
| return 0; |
| } |
| |
| /* |
| * Migrate memory region from one set of nodes to another. This is |
| * performed asynchronously as it can be called from process migration path |
| * holding locks involved in process management. All mm migrations are |
| * performed in the queued order and can be waited for by flushing |
| * cpuset_migrate_mm_wq. |
| */ |
| |
| struct cpuset_migrate_mm_work { |
| struct work_struct work; |
| struct mm_struct *mm; |
| nodemask_t from; |
| nodemask_t to; |
| }; |
| |
| static void cpuset_migrate_mm_workfn(struct work_struct *work) |
| { |
| struct cpuset_migrate_mm_work *mwork = |
| container_of(work, struct cpuset_migrate_mm_work, work); |
| |
| /* on a wq worker, no need to worry about %current's mems_allowed */ |
| do_migrate_pages(mwork->mm, &mwork->from, &mwork->to, MPOL_MF_MOVE_ALL); |
| mmput(mwork->mm); |
| kfree(mwork); |
| } |
| |
| static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, |
| const nodemask_t *to) |
| { |
| struct cpuset_migrate_mm_work *mwork; |
| |
| mwork = kzalloc(sizeof(*mwork), GFP_KERNEL); |
| if (mwork) { |
| mwork->mm = mm; |
| mwork->from = *from; |
| mwork->to = *to; |
| INIT_WORK(&mwork->work, cpuset_migrate_mm_workfn); |
| queue_work(cpuset_migrate_mm_wq, &mwork->work); |
| } else { |
| mmput(mm); |
| } |
| } |
| |
| static void cpuset_post_attach(void) |
| { |
| flush_workqueue(cpuset_migrate_mm_wq); |
| } |
| |
| /* |
| * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy |
| * @tsk: the task to change |
| * @newmems: new nodes that the task will be set |
| * |
| * We use the mems_allowed_seq seqlock to safely update both tsk->mems_allowed |
| * and rebind an eventual tasks' mempolicy. If the task is allocating in |
| * parallel, it might temporarily see an empty intersection, which results in |
| * a seqlock check and retry before OOM or allocation failure. |
| */ |
| static void cpuset_change_task_nodemask(struct task_struct *tsk, |
| nodemask_t *newmems) |
| { |
| task_lock(tsk); |
| |
| local_irq_disable(); |
| write_seqcount_begin(&tsk->mems_allowed_seq); |
| |
| nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems); |
| mpol_rebind_task(tsk, newmems); |
| tsk->mems_allowed = *newmems; |
| |
| write_seqcount_end(&tsk->mems_allowed_seq); |
| local_irq_enable(); |
| |
| task_unlock(tsk); |
| } |
| |
| static void *cpuset_being_rebound; |
| |
| /** |
| * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset. |
| * @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, |
| * cpuset membership stays stable. |
| */ |
| static void update_tasks_nodemask(struct cpuset *cs) |
| { |
| static nodemask_t newmems; /* protected by cpuset_mutex */ |
| struct css_task_iter it; |
| struct task_struct *task; |
| |
| cpuset_being_rebound = cs; /* causes mpol_dup() rebind */ |
| |
| guarantee_online_mems(cs, &newmems); |
| |
| /* |
| * The mpol_rebind_mm() call takes mmap_sem, 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 |
| * 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. |
| */ |
| css_task_iter_start(&cs->css, 0, &it); |
| while ((task = css_task_iter_next(&it))) { |
| struct mm_struct *mm; |
| bool migrate; |
| |
| cpuset_change_task_nodemask(task, &newmems); |
| |
| mm = get_task_mm(task); |
| if (!mm) |
| continue; |
| |
| migrate = is_memory_migrate(cs); |
| |
| mpol_rebind_mm(mm, &cs->mems_allowed); |
| if (migrate) |
| cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems); |
| else |
| mmput(mm); |
| } |
| css_task_iter_end(&it); |
| |
| /* |
| * All the tasks' nodemasks have been updated, update |
| * cs->old_mems_allowed. |
| */ |
| cs->old_mems_allowed = newmems; |
| |
| /* We're done rebinding vmas to this cpuset's new mems_allowed. */ |
| cpuset_being_rebound = NULL; |
| } |
| |
| /* |
| * update_nodemasks_hier - Update effective nodemasks and tasks in the subtree |
| * @cs: the cpuset to consider |
| * @new_mems: a temp variable for calculating new effective_mems |
| * |
| * 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. |
| * |
| * Called with cpuset_mutex held |
| */ |
| static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems) |
| { |
| struct cpuset *cp; |
| struct cgroup_subsys_state *pos_css; |
| |
| rcu_read_lock(); |
| cpuset_for_each_descendant_pre(cp, pos_css, cs) { |
| struct cpuset *parent = parent_cs(cp); |
| |
| nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems); |
| |
| /* |
| * If it becomes empty, inherit the effective mask of the |
| * parent, which is guaranteed to have some MEMs. |
| */ |
| if (is_in_v2_mode() && nodes_empty(*new_mems)) |
| *new_mems = parent->effective_mems; |
| |
| /* Skip the whole subtree if the nodemask remains the same. */ |
| if (nodes_equal(*new_mems, cp->effective_mems)) { |
| pos_css = css_rightmost_descendant(pos_css); |
| continue; |
| } |
| |
| if (!css_tryget_online(&cp->css)) |
| continue; |
| rcu_read_unlock(); |
| |
| spin_lock_irq(&callback_lock); |
| cp->effective_mems = *new_mems; |
| spin_unlock_irq(&callback_lock); |
| |
| WARN_ON(!is_in_v2_mode() && |
| !nodes_equal(cp->mems_allowed, cp->effective_mems)); |
| |
| update_tasks_nodemask(cp); |
| |
| rcu_read_lock(); |
| css_put(&cp->css); |
| } |
| rcu_read_unlock(); |
| } |
| |
| /* |
| * Handle user request to change the 'mems' memory placement |
| * of a cpuset. Needs to validate the request, update the |
| * cpusets mems_allowed, and for each task in the cpuset, |
| * update mems_allowed and rebind task's mempolicy and any vma |
| * 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. |
| * Will take tasklist_lock, scan tasklist for tasks in cpuset cs, |
| * lock each such tasks mm->mmap_sem, scan its vma's and rebind |
| * their mempolicies to the cpusets new mems_allowed. |
| */ |
| static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, |
| const char *buf) |
| { |
| int retval; |
| |
| /* |
| * top_cpuset.mems_allowed tracks node_stats[N_MEMORY]; |
| * it's read-only |
| */ |
| if (cs == &top_cpuset) { |
| retval = -EACCES; |
| goto done; |
| } |
| |
| /* |
| * An empty mems_allowed is ok iff there are no tasks in the cpuset. |
| * Since nodelist_parse() fails on an empty mask, we special case |
| * that parsing. The validate_change() call ensures that cpusets |
| * with tasks have memory. |
| */ |
| if (!*buf) { |
| nodes_clear(trialcs->mems_allowed); |
| } else { |
| retval = nodelist_parse(buf, trialcs->mems_allowed); |
| if (retval < 0) |
| goto done; |
| |
| if (!nodes_subset(trialcs->mems_allowed, |
| top_cpuset.mems_allowed)) { |
| retval = -EINVAL; |
| goto done; |
| } |
| } |
| |
| if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) { |
| retval = 0; /* Too easy - nothing to do */ |
| goto done; |
| } |
| retval = validate_change(cs, trialcs); |
| if (retval < 0) |
| goto done; |
| |
| spin_lock_irq(&callback_lock); |
| cs->mems_allowed = trialcs->mems_allowed; |
| spin_unlock_irq(&callback_lock); |
| |
| /* use trialcs->mems_allowed as a temp variable */ |
| update_nodemasks_hier(cs, &trialcs->mems_allowed); |
| done: |
| return retval; |
| } |
| |
| bool current_cpuset_is_being_rebound(void) |
| { |
| bool ret; |
| |
| rcu_read_lock(); |
| ret = task_cs(current) == cpuset_being_rebound; |
| rcu_read_unlock(); |
| |
| return ret; |
| } |
| |
| static int update_relax_domain_level(struct cpuset *cs, s64 val) |
| { |
| #ifdef CONFIG_SMP |
| if (val < -1 || val >= sched_domain_level_max) |
| return -EINVAL; |
| #endif |
| |
| if (val != cs->relax_domain_level) { |
| cs->relax_domain_level = val; |
| if (!cpumask_empty(cs->cpus_allowed) && |
| is_sched_load_balance(cs)) |
| rebuild_sched_domains_locked(); |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * update_tasks_flags - update the spread flags of tasks in the cpuset. |
| * @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 |
| * stable. |
| */ |
| static void update_tasks_flags(struct cpuset *cs) |
| { |
| struct css_task_iter it; |
| struct task_struct *task; |
| |
| css_task_iter_start(&cs->css, 0, &it); |
| while ((task = css_task_iter_next(&it))) |
| cpuset_update_task_spread_flag(cs, task); |
| css_task_iter_end(&it); |
| } |
| |
| /* |
| * update_flag - read a 0 or a 1 in a file and update associated flag |
| * bit: the bit to update (see cpuset_flagbits_t) |
| * cs: the cpuset to update |
| * turning_on: whether the flag is being set or cleared |
| * |
| * Call with cpuset_mutex held. |
| */ |
| |
| static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, |
| int turning_on) |
| { |
| struct cpuset *trialcs; |
| int balance_flag_changed; |
| int spread_flag_changed; |
| int err; |
| |
| trialcs = alloc_trial_cpuset(cs); |
| if (!trialcs) |
| return -ENOMEM; |
| |
| if (turning_on) |
| set_bit(bit, &trialcs->flags); |
| else |
| clear_bit(bit, &trialcs->flags); |
| |
| err = validate_change(cs, trialcs); |
| if (err < 0) |
| goto out; |
| |
| balance_flag_changed = (is_sched_load_balance(cs) != |
| is_sched_load_balance(trialcs)); |
| |
| spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs)) |
| || (is_spread_page(cs) != is_spread_page(trialcs))); |
| |
| spin_lock_irq(&callback_lock); |
| cs->flags = trialcs->flags; |
| spin_unlock_irq(&callback_lock); |
| |
| if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed) |
| rebuild_sched_domains_locked(); |
| |
| if (spread_flag_changed) |
| update_tasks_flags(cs); |
| out: |
| free_cpuset(trialcs); |
| return err; |
| } |
| |
| /* |
| * update_prstate - update partititon_root_state |
| * cs: the cpuset to update |
| * val: 0 - disabled, 1 - enabled |
| * |
| * Call with cpuset_mutex held. |
| */ |
| static int update_prstate(struct cpuset *cs, int val) |
| { |
| int err; |
| struct cpuset *parent = parent_cs(cs); |
| struct tmpmasks tmp; |
| |
| if ((val != 0) && (val != 1)) |
| return -EINVAL; |
| if (val == cs->partition_root_state) |
| return 0; |
| |
| /* |
| * Cannot force a partial or invalid partition root to a full |
| * partition root. |
| */ |
| if (val && cs->partition_root_state) |
| return -EINVAL; |
| |
| if (alloc_cpumasks(NULL, &tmp)) |
| return -ENOMEM; |
| |
| err = -EINVAL; |
| if (!cs->partition_root_state) { |
| /* |
| * Turning on partition root requires setting the |
| * CS_CPU_EXCLUSIVE bit implicitly as well and cpus_allowed |
| * cannot be NULL. |
| */ |
| if (cpumask_empty(cs->cpus_allowed)) |
| goto out; |
| |
| err = update_flag(CS_CPU_EXCLUSIVE, cs, 1); |
| if (err) |
| goto out; |
| |
| err = update_parent_subparts_cpumask(cs, partcmd_enable, |
| NULL, &tmp); |
| if (err) { |
| update_flag(CS_CPU_EXCLUSIVE, cs, 0); |
| goto out; |
| } |
| cs->partition_root_state = PRS_ENABLED; |
| } else { |
| /* |
| * Turning off partition root will clear the |
| * CS_CPU_EXCLUSIVE bit. |
| */ |
| if (cs->partition_root_state == PRS_ERROR) { |
| cs->partition_root_state = 0; |
| update_flag(CS_CPU_EXCLUSIVE, cs, 0); |
| err = 0; |
| goto out; |
| } |
| |
| err = update_parent_subparts_cpumask(cs, partcmd_disable, |
| NULL, &tmp); |
| if (err) |
| goto out; |
| |
| cs->partition_root_state = 0; |
| |
| /* Turning off CS_CPU_EXCLUSIVE will not return error */ |
| 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); |
| |
| if (parent->child_ecpus_count) |
| update_sibling_cpumasks(parent, cs, &tmp); |
| |
| rebuild_sched_domains_locked(); |
| out: |
| free_cpumasks(NULL, &tmp); |
| return err; |
| } |
| |
| /* |
| * Frequency meter - How fast is some event occurring? |
| * |
| * These routines manage a digitally filtered, constant time based, |
| * event frequency meter. There are four routines: |
| * fmeter_init() - initialize a frequency meter. |
| * fmeter_markevent() - called each time the event happens. |
| * fmeter_getrate() - returns the recent rate of such events. |
| * fmeter_update() - internal routine used to update fmeter. |
| * |
| * A common data structure is passed to each of these routines, |
| * which is used to keep track of the state required to manage the |
| * frequency meter and its digital filter. |
| * |
| * The filter works on the number of events marked per unit time. |
| * The filter is single-pole low-pass recursive (IIR). The time unit |
| * is 1 second. Arithmetic is done using 32-bit integers scaled to |
| * simulate 3 decimal digits of precision (multiplied by 1000). |
| * |
| * With an FM_COEF of 933, and a time base of 1 second, the filter |
| * has a half-life of 10 seconds, meaning that if the events quit |
| * happening, then the rate returned from the fmeter_getrate() |
| * will be cut in half each 10 seconds, until it converges to zero. |
| * |
| * It is not worth doing a real infinitely recursive filter. If more |
| * than FM_MAXTICKS ticks have elapsed since the last filter event, |
| * just compute FM_MAXTICKS ticks worth, by which point the level |
| * will be stable. |
| * |
| * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid |
| * arithmetic overflow in the fmeter_update() routine. |
| * |
| * Given the simple 32 bit integer arithmetic used, this meter works |
| * best for reporting rates between one per millisecond (msec) and |
| * one per 32 (approx) seconds. At constant rates faster than one |
| * per msec it maxes out at values just under 1,000,000. At constant |
| * rates between one per msec, and one per second it will stabilize |
| * to a value N*1000, where N is the rate of events per second. |
| * At constant rates between one per second and one per 32 seconds, |
| * it will be choppy, moving up on the seconds that have an event, |
| * and then decaying until the next event. At rates slower than |
| * about one in 32 seconds, it decays all the way back to zero between |
| * each event. |
| */ |
| |
| #define FM_COEF 933 /* coefficient for half-life of 10 secs */ |
| #define FM_MAXTICKS ((u32)99) /* useless computing more ticks than this */ |
| #define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */ |
| #define FM_SCALE 1000 /* faux fixed point scale */ |
| |
| /* Initialize a frequency meter */ |
| static void fmeter_init(struct fmeter *fmp) |
| { |
| fmp->cnt = 0; |
| fmp->val = 0; |
| fmp->time = 0; |
| spin_lock_init(&fmp->lock); |
| } |
| |
| /* Internal meter update - process cnt events and update value */ |
| static void fmeter_update(struct fmeter *fmp) |
| { |
| time64_t now; |
| u32 ticks; |
| |
| now = ktime_get_seconds(); |
| ticks = now - fmp->time; |
| |
| if (ticks == 0) |
| return; |
| |
| ticks = min(FM_MAXTICKS, ticks); |
| while (ticks-- > 0) |
| fmp->val = (FM_COEF * fmp->val) / FM_SCALE; |
| fmp->time = now; |
| |
| fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE; |
| fmp->cnt = 0; |
| } |
| |
| /* Process any previous ticks, then bump cnt by one (times scale). */ |
| static void fmeter_markevent(struct fmeter *fmp) |
| { |
| spin_lock(&fmp->lock); |
| fmeter_update(fmp); |
| fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE); |
| spin_unlock(&fmp->lock); |
| } |
| |
| /* Process any previous ticks, then return current value. */ |
| static int fmeter_getrate(struct fmeter *fmp) |
| { |
| int val; |
| |
| spin_lock(&fmp->lock); |
| fmeter_update(fmp); |
| val = fmp->val; |
| spin_unlock(&fmp->lock); |
| return val; |
| } |
| |
| static struct cpuset *cpuset_attach_old_cs; |
| |
| /* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */ |
| static int cpuset_can_attach(struct cgroup_taskset *tset) |
| { |
| struct cgroup_subsys_state *css; |
| struct cpuset *cs; |
| struct task_struct *task; |
| int ret; |
| |
| /* used later by cpuset_attach() */ |
| cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css)); |
| cs = css_cs(css); |
| |
| mutex_lock(&cpuset_mutex); |
| |
| /* allow moving tasks into an empty cpuset if on default hierarchy */ |
| ret = -ENOSPC; |
| if (!is_in_v2_mode() && |
| (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))) |
| goto out_unlock; |
| |
| cgroup_taskset_for_each(task, css, tset) { |
| ret = task_can_attach(task, cs->cpus_allowed); |
| if (ret) |
| goto out_unlock; |
| ret = security_task_setscheduler(task); |
| if (ret) |
| goto out_unlock; |
| } |
| |
| /* |
| * Mark attach is in progress. This makes validate_change() fail |
| * changes which zero cpus/mems_allowed. |
| */ |
| cs->attach_in_progress++; |
| ret = 0; |
| out_unlock: |
| mutex_unlock(&cpuset_mutex); |
| return ret; |
| } |
| |
| static void cpuset_cancel_attach(struct cgroup_taskset *tset) |
| { |
| struct cgroup_subsys_state *css; |
| |
| cgroup_taskset_first(tset, &css); |
| |
| mutex_lock(&cpuset_mutex); |
| css_cs(css)->attach_in_progress--; |
| mutex_unlock(&cpuset_mutex); |
| } |
| |
| /* |
| * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach() |
| * but we can't allocate it dynamically there. Define it global and |
| * allocate from cpuset_init(). |
| */ |
| static cpumask_var_t cpus_attach; |
| |
| static void cpuset_attach(struct cgroup_taskset *tset) |
| { |
| /* static buf protected by cpuset_mutex */ |
| static nodemask_t cpuset_attach_nodemask_to; |
| struct task_struct *task; |
| struct task_struct *leader; |
| struct cgroup_subsys_state *css; |
| struct cpuset *cs; |
| struct cpuset *oldcs = cpuset_attach_old_cs; |
| |
| cgroup_taskset_first(tset, &css); |
| cs = css_cs(css); |
| |
| mutex_lock(&cpuset_mutex); |
| |
| /* 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) { |
| /* |
| * can_attach beforehand should guarantee that this doesn't |
| * fail. TODO: have a better way to handle failure here |
| */ |
| WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach)); |
| |
| cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to); |
| cpuset_update_task_spread_flag(cs, task); |
| } |
| |
| /* |
| * Change mm for all threadgroup leaders. This is expensive and may |
| * sleep and should be moved outside migration path proper. |
| */ |
| cpuset_attach_nodemask_to = cs->effective_mems; |
| cgroup_taskset_for_each_leader(leader, css, tset) { |
| struct mm_struct *mm = get_task_mm(leader); |
| |
| if (mm) { |
| mpol_rebind_mm(mm, &cpuset_attach_nodemask_to); |
| |
| /* |
| * old_mems_allowed is the same with mems_allowed |
| * here, except if this task is being moved |
| * automatically due to hotplug. In that case |
| * @mems_allowed has been updated and is empty, so |
| * @old_mems_allowed is the right nodesets that we |
| * migrate mm from. |
| */ |
| if (is_memory_migrate(cs)) |
| cpuset_migrate_mm(mm, &oldcs->old_mems_allowed, |
| &cpuset_attach_nodemask_to); |
| else |
| mmput(mm); |
| } |
| } |
| |
| cs->old_mems_allowed = cpuset_attach_nodemask_to; |
| |
| cs->attach_in_progress--; |
| if (!cs->attach_in_progress) |
| wake_up(&cpuset_attach_wq); |
| |
| mutex_unlock(&cpuset_mutex); |
| } |
| |
| /* The various types of files and directories in a cpuset file system */ |
| |
| typedef enum { |
| FILE_MEMORY_MIGRATE, |
| FILE_CPULIST, |
| FILE_MEMLIST, |
| FILE_EFFECTIVE_CPULIST, |
| FILE_EFFECTIVE_MEMLIST, |
| FILE_SUBPARTS_CPULIST, |
| FILE_CPU_EXCLUSIVE, |
| FILE_MEM_EXCLUSIVE, |
| FILE_MEM_HARDWALL, |
| FILE_SCHED_LOAD_BALANCE, |
| FILE_PARTITION_ROOT, |
| FILE_SCHED_RELAX_DOMAIN_LEVEL, |
| FILE_MEMORY_PRESSURE_ENABLED, |
| FILE_MEMORY_PRESSURE, |
| FILE_SPREAD_PAGE, |
| FILE_SPREAD_SLAB, |
| } cpuset_filetype_t; |
| |
| static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft, |
| u64 val) |
| { |
| struct cpuset *cs = css_cs(css); |
| cpuset_filetype_t type = cft->private; |
| int retval = 0; |
| |
| mutex_lock(&cpuset_mutex); |
| if (!is_cpuset_online(cs)) { |
| retval = -ENODEV; |
| goto out_unlock; |
| } |
| |
| switch (type) { |
| case FILE_CPU_EXCLUSIVE: |
| retval = update_flag(CS_CPU_EXCLUSIVE, cs, val); |
| break; |
| case FILE_MEM_EXCLUSIVE: |
| retval = update_flag(CS_MEM_EXCLUSIVE, cs, val); |
| break; |
| case FILE_MEM_HARDWALL: |
| retval = update_flag(CS_MEM_HARDWALL, cs, val); |
| break; |
| case FILE_SCHED_LOAD_BALANCE: |
| retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val); |
| break; |
| case FILE_MEMORY_MIGRATE: |
| retval = update_flag(CS_MEMORY_MIGRATE, cs, val); |
| break; |
| case FILE_MEMORY_PRESSURE_ENABLED: |
| cpuset_memory_pressure_enabled = !!val; |
| break; |
| case FILE_SPREAD_PAGE: |
| retval = update_flag(CS_SPREAD_PAGE, cs, val); |
| break; |
| case FILE_SPREAD_SLAB: |
| retval = update_flag(CS_SPREAD_SLAB, cs, val); |
| break; |
| default: |
| retval = -EINVAL; |
| break; |
| } |
| out_unlock: |
| mutex_unlock(&cpuset_mutex); |
| return retval; |
| } |
| |
| static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft, |
| s64 val) |
| { |
| struct cpuset *cs = css_cs(css); |
| cpuset_filetype_t type = cft->private; |
| int retval = -ENODEV; |
| |
| mutex_lock(&cpuset_mutex); |
| if (!is_cpuset_online(cs)) |
| goto out_unlock; |
| |
| switch (type) { |
| case FILE_SCHED_RELAX_DOMAIN_LEVEL: |
| retval = update_relax_domain_level(cs, val); |
| break; |
| default: |
| retval = -EINVAL; |
| break; |
| } |
| out_unlock: |
| mutex_unlock(&cpuset_mutex); |
| return retval; |
| } |
| |
| /* |
| * Common handling for a write to a "cpus" or "mems" file. |
| */ |
| static ssize_t cpuset_write_resmask(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, loff_t off) |
| { |
| struct cpuset *cs = css_cs(of_css(of)); |
| struct cpuset *trialcs; |
| int retval = -ENODEV; |
| |
| buf = strstrip(buf); |
| |
| /* |
| * CPU or memory hotunplug may leave @cs w/o any execution |
| * resources, in which case the hotplug code asynchronously updates |
| * configuration and transfers all tasks to the nearest ancestor |
| * which can execute. |
| * |
| * As writes to "cpus" or "mems" may restore @cs's execution |
| * resources, wait for the previously scheduled operations before |
| * proceeding, so that we don't end up keep removing tasks added |
| * after execution capability is restored. |
| * |
| * cpuset_hotplug_work calls back into cgroup core via |
| * cgroup_transfer_tasks() and waiting for it from a cgroupfs |
| * 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 |
| * hierarchies. |
| */ |
| css_get(&cs->css); |
| kernfs_break_active_protection(of->kn); |
| flush_work(&cpuset_hotplug_work); |
| |
| mutex_lock(&cpuset_mutex); |
| if (!is_cpuset_online(cs)) |
| goto out_unlock; |
| |
| trialcs = alloc_trial_cpuset(cs); |
| if (!trialcs) { |
| retval = -ENOMEM; |
| goto out_unlock; |
| } |
| |
| switch (of_cft(of)->private) { |
| case FILE_CPULIST: |
| retval = update_cpumask(cs, trialcs, buf); |
| break; |
| case FILE_MEMLIST: |
| retval = update_nodemask(cs, trialcs, buf); |
| break; |
| default: |
| retval = -EINVAL; |
| break; |
| } |
| |
| free_cpuset(trialcs); |
| out_unlock: |
| mutex_unlock(&cpuset_mutex); |
| kernfs_unbreak_active_protection(of->kn); |
| css_put(&cs->css); |
| flush_workqueue(cpuset_migrate_mm_wq); |
| return retval ?: nbytes; |
| } |
| |
| /* |
| * These ascii lists should be read in a single call, by using a user |
| * buffer large enough to hold the entire map. If read in smaller |
| * chunks, there is no guarantee of atomicity. Since the display format |
| * used, list of ranges of sequential numbers, is variable length, |
| * and since these maps can change value dynamically, one could read |
| * gibberish by doing partial reads while a list was changing. |
| */ |
| static int cpuset_common_seq_show(struct seq_file *sf, void *v) |
| { |
| struct cpuset *cs = css_cs(seq_css(sf)); |
| cpuset_filetype_t type = seq_cft(sf)->private; |
| int ret = 0; |
| |
| spin_lock_irq(&callback_lock); |
| |
| switch (type) { |
| case FILE_CPULIST: |
| seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->cpus_allowed)); |
| break; |
| case FILE_MEMLIST: |
| seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->mems_allowed)); |
| break; |
| case FILE_EFFECTIVE_CPULIST: |
| seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->effective_cpus)); |
| break; |
| case FILE_EFFECTIVE_MEMLIST: |
| seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems)); |
| break; |
| case FILE_SUBPARTS_CPULIST: |
| seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->subparts_cpus)); |
| break; |
| default: |
| ret = -EINVAL; |
| } |
| |
| spin_unlock_irq(&callback_lock); |
| return ret; |
| } |
| |
| static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft) |
| { |
| struct cpuset *cs = css_cs(css); |
| cpuset_filetype_t type = cft->private; |
| switch (type) { |
| case FILE_CPU_EXCLUSIVE: |
| return is_cpu_exclusive(cs); |
| case FILE_MEM_EXCLUSIVE: |
| return is_mem_exclusive(cs); |
| case FILE_MEM_HARDWALL: |
| return is_mem_hardwall(cs); |
| case FILE_SCHED_LOAD_BALANCE: |
| return is_sched_load_balance(cs); |
| case FILE_MEMORY_MIGRATE: |
| return is_memory_migrate(cs); |
| case FILE_MEMORY_PRESSURE_ENABLED: |
| return cpuset_memory_pressure_enabled; |
| case FILE_MEMORY_PRESSURE: |
| return fmeter_getrate(&cs->fmeter); |
| case FILE_SPREAD_PAGE: |
| return is_spread_page(cs); |
| case FILE_SPREAD_SLAB: |
| return is_spread_slab(cs); |
| default: |
| BUG(); |
| } |
| |
| /* Unreachable but makes gcc happy */ |
| return 0; |
| } |
| |
| static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft) |
| { |
| struct cpuset *cs = css_cs(css); |
| cpuset_filetype_t type = cft->private; |
| switch (type) { |
| case FILE_SCHED_RELAX_DOMAIN_LEVEL: |
| return cs->relax_domain_level; |
| default: |
| BUG(); |
| } |
| |
| /* Unrechable 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)); |
| |
| switch (cs->partition_root_state) { |
| case PRS_ENABLED: |
| seq_puts(seq, "root\n"); |
| break; |
| case PRS_DISABLED: |
| seq_puts(seq, "member\n"); |
| break; |
| case PRS_ERROR: |
| seq_puts(seq, "root invalid\n"); |
| break; |
| } |
| return 0; |
| } |
| |
| static ssize_t sched_partition_write(struct kernfs_open_file *of, char *buf, |
| size_t nbytes, loff_t off) |
| { |
| struct cpuset *cs = css_cs(of_css(of)); |
| int val; |
| int retval = -ENODEV; |
| |
| buf = strstrip(buf); |
| |
| /* |
| * Convert "root" to ENABLED, and convert "member" to DISABLED. |
| */ |
| if (!strcmp(buf, "root")) |
| val = PRS_ENABLED; |
| else if (!strcmp(buf, "member")) |
| val = PRS_DISABLED; |
| else |
| return -EINVAL; |
| |
| css_get(&cs->css); |
| mutex_lock(&cpuset_mutex); |
| if (!is_cpuset_online(cs)) |
| goto out_unlock; |
| |
| retval = update_prstate(cs, val); |
| out_unlock: |
| mutex_unlock(&cpuset_mutex); |
| css_put(&cs->css); |
| return retval ?: nbytes; |
| } |
| |
| /* |
| * for the common functions, 'private' gives the type of file |
| */ |
| |
| static struct cftype legacy_files[] = { |
| { |
| .name = "cpus", |
| .seq_show = cpuset_common_seq_show, |
| .write = cpuset_write_resmask, |
| .max_write_len = (100U + 6 * NR_CPUS), |
| .private = FILE_CPULIST, |
| }, |
| |
| { |
| .name = "mems", |
| .seq_show = cpuset_common_seq_show, |
| .write = cpuset_write_resmask, |
| .max_write_len = (100U + 6 * MAX_NUMNODES), |
| .private = FILE_MEMLIST, |
| }, |
| |
| { |
| .name = "effective_cpus", |
| .seq_show = cpuset_common_seq_show, |
| .private = FILE_EFFECTIVE_CPULIST, |
| }, |
| |
| { |
| .name = "effective_mems", |
| .seq_show = cpuset_common_seq_show, |
| .private = FILE_EFFECTIVE_MEMLIST, |
| }, |
| |
| { |
| .name = "cpu_exclusive", |
| .read_u64 = cpuset_read_u64, |
| .write_u64 = cpuset_write_u64, |
| .private = FILE_CPU_EXCLUSIVE, |
| }, |
| |
| { |
| .name = "mem_exclusive", |
| .read_u64 = cpuset_read_u64, |
| .write_u64 = cpuset_write_u64, |
| .private = FILE_MEM_EXCLUSIVE, |
| }, |
| |
| { |
| .name = "mem_hardwall", |
| .read_u64 = cpuset_read_u64, |
| .write_u64 = cpuset_write_u64, |
| .private = FILE_MEM_HARDWALL, |
| }, |
| |
| { |
| .name = "sched_load_balance", |
| .read_u64 = cpuset_read_u64, |
| .write_u64 = cpuset_write_u64, |
| .private = FILE_SCHED_LOAD_BALANCE, |
| }, |
| |
| { |
| .name = "sched_relax_domain_level", |
| .read_s64 = cpuset_read_s64, |
| .write_s64 = cpuset_write_s64, |
| .private = FILE_SCHED_RELAX_DOMAIN_LEVEL, |
| }, |
| |
| { |
| .name = "memory_migrate", |
| .read_u64 = cpuset_read_u64, |
| .write_u64 = cpuset_write_u64, |
| .private = FILE_MEMORY_MIGRATE, |
| }, |
| |
| { |
| .name = "memory_pressure", |
| .read_u64 = cpuset_read_u64, |
| .private = FILE_MEMORY_PRESSURE, |
| }, |
| |
| { |
| .name = "memory_spread_page", |
| .read_u64 = cpuset_read_u64, |
| .write_u64 = cpuset_write_u64, |
| .private = FILE_SPREAD_PAGE, |
| }, |
| |
| { |
| .name = "memory_spread_slab", |
| .read_u64 = cpuset_read_u64, |
| .write_u64 = cpuset_write_u64, |
| .private = FILE_SPREAD_SLAB, |
| }, |
| |
| { |
| .name = "memory_pressure_enabled", |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| .read_u64 = cpuset_read_u64, |
| .write_u64 = cpuset_write_u64, |
| .private = FILE_MEMORY_PRESSURE_ENABLED, |
| }, |
| |
| { } /* terminate */ |
| }; |
| |
| /* |
| * This is currently a minimal set for the default hierarchy. It can be |
| * expanded later on by migrating more features and control files from v1. |
| */ |
| static struct cftype dfl_files[] = { |
| { |
| .name = "cpus", |
| .seq_show = cpuset_common_seq_show, |
| .write = cpuset_write_resmask, |
| .max_write_len = (100U + 6 * NR_CPUS), |
| .private = FILE_CPULIST, |
| .flags = CFTYPE_NOT_ON_ROOT, |
| }, |
| |
| { |
| .name = "mems", |
| .seq_show = cpuset_common_seq_show, |
| .write = cpuset_write_resmask, |
| .max_write_len = (100U + 6 * MAX_NUMNODES), |
| .private = FILE_MEMLIST, |
| .flags = CFTYPE_NOT_ON_ROOT, |
| }, |
| |
| { |
| .name = "cpus.effective", |
| .seq_show = cpuset_common_seq_show, |
| .private = FILE_EFFECTIVE_CPULIST, |
| }, |
| |
| { |
| .name = "mems.effective", |
| .seq_show = cpuset_common_seq_show, |
| .private = FILE_EFFECTIVE_MEMLIST, |
| }, |
| |
| { |
| .name = "cpus.partition", |
| .seq_show = sched_partition_show, |
| .write = sched_partition_write, |
| .private = FILE_PARTITION_ROOT, |
| .flags = CFTYPE_NOT_ON_ROOT, |
| }, |
| |
| { |
| .name = "cpus.subpartitions", |
| .seq_show = cpuset_common_seq_show, |
| .private = FILE_SUBPARTS_CPULIST, |
| .flags = CFTYPE_DEBUG, |
| }, |
| |
| { } /* terminate */ |
| }; |
| |
| |
| /* |
| * cpuset_css_alloc - allocate a cpuset css |
| * cgrp: control group that the new cpuset will be part of |
| */ |
| |
| static struct cgroup_subsys_state * |
| cpuset_css_alloc(struct cgroup_subsys_state *parent_css) |
| { |
| struct cpuset *cs; |
| |
| if (!parent_css) |
| return &top_cpuset.css; |
| |
| cs = kzalloc(sizeof(*cs), GFP_KERNEL); |
| if (!cs) |
| return ERR_PTR(-ENOMEM); |
| |
| if (alloc_cpumasks(cs, NULL)) { |
| kfree(cs); |
| return ERR_PTR(-ENOMEM); |
| } |
| |
| 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; |
| |
| return &cs->css; |
| } |
| |
| static int cpuset_css_online(struct cgroup_subsys_state *css) |
| { |
| struct cpuset *cs = css_cs(css); |
| struct cpuset *parent = parent_cs(cs); |
| struct cpuset *tmp_cs; |
| struct cgroup_subsys_state *pos_css; |
| |
| if (!parent) |
| return 0; |
| |
| mutex_lock(&cpuset_mutex); |
| |
| set_bit(CS_ONLINE, &cs->flags); |
| if (is_spread_page(parent)) |
| set_bit(CS_SPREAD_PAGE, &cs->flags); |
| if (is_spread_slab(parent)) |
| set_bit(CS_SPREAD_SLAB, &cs->flags); |
| |
| cpuset_inc(); |
| |
| spin_lock_irq(&callback_lock); |
| if (is_in_v2_mode()) { |
| cpumask_copy(cs->effective_cpus, parent->effective_cpus); |
| cs->effective_mems = parent->effective_mems; |
| cs->use_parent_ecpus = true; |
| parent->child_ecpus_count++; |
| } |
| spin_unlock_irq(&callback_lock); |
| |
| if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags)) |
| goto out_unlock; |
| |
| /* |
| * 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. |
| * |
| * Currently, if any sibling cpusets have exclusive cpus or mem, we |
| * refuse to clone the configuration - thereby refusing the task to |
| * be entered, and as a result refusing the sys_unshare() or |
| * clone() which initiated it. If this becomes a problem for some |
| * users who wish to allow that scenario, then this could be |
| * changed to grant parent->cpus_allowed-sibling_cpus_exclusive |
| * (and likewise for mems) to the new cgroup. |
| */ |
| rcu_read_lock(); |
| cpuset_for_each_child(tmp_cs, pos_css, parent) { |
| if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) { |
| rcu_read_unlock(); |
| goto out_unlock; |
| } |
| } |
| rcu_read_unlock(); |
| |
| spin_lock_irq(&callback_lock); |
| cs->mems_allowed = parent->mems_allowed; |
| cs->effective_mems = parent->mems_allowed; |
| cpumask_copy(cs->cpus_allowed, parent->cpus_allowed); |
| cpumask_copy(cs->effective_cpus, parent->cpus_allowed); |
| spin_unlock_irq(&callback_lock); |
| out_unlock: |
| mutex_unlock(&cpuset_mutex); |
| return 0; |
| } |
| |
| /* |
| * If the cpuset being removed has its flag 'sched_load_balance' |
| * enabled, then simulate turning sched_load_balance off, which |
| * will call rebuild_sched_domains_locked(). That is not needed |
| * in the default hierarchy where only changes in partition |
| * will cause repartitioning. |
| * |
| * If the cpuset has the 'sched.partition' flag enabled, simulate |
| * turning 'sched.partition" off. |
| */ |
| |
| static void cpuset_css_offline(struct cgroup_subsys_state *css) |
| { |
| struct cpuset *cs = css_cs(css); |
| |
| mutex_lock(&cpuset_mutex); |
| |
| if (is_partition_root(cs)) |
| update_prstate(cs, 0); |
| |
| if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && |
| is_sched_load_balance(cs)) |
| update_flag(CS_SCHED_LOAD_BALANCE, cs, 0); |
| |
| if (cs->use_parent_ecpus) { |
| struct cpuset *parent = parent_cs(cs); |
| |
| cs->use_parent_ecpus = false; |
| parent->child_ecpus_count--; |
| } |
| |
| cpuset_dec(); |
| clear_bit(CS_ONLINE, &cs->flags); |
| |
| mutex_unlock(&cpuset_mutex); |
| } |
| |
| static void cpuset_css_free(struct cgroup_subsys_state *css) |
| { |
| struct cpuset *cs = css_cs(css); |
| |
| free_cpuset(cs); |
| } |
| |
| static void cpuset_bind(struct cgroup_subsys_state *root_css) |
| { |
| mutex_lock(&cpuset_mutex); |
| spin_lock_irq(&callback_lock); |
| |
| if (is_in_v2_mode()) { |
| cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask); |
| top_cpuset.mems_allowed = node_possible_map; |
| } else { |
| cpumask_copy(top_cpuset.cpus_allowed, |
| top_cpuset.effective_cpus); |
| top_cpuset.mems_allowed = top_cpuset.effective_mems; |
| } |
| |
| spin_unlock_irq(&callback_lock); |
| mutex_unlock(&cpuset_mutex); |
| } |
| |
| /* |
| * Make sure the new task conform to the current state of its parent, |
| * which could have been changed by cpuset just after it inherits the |
| * state from the parent and before it sits on the cgroup's task list. |
| */ |
| static void cpuset_fork(struct task_struct *task) |
| { |
| if (task_css_is_root(task, cpuset_cgrp_id)) |
| return; |
| |
| set_cpus_allowed_ptr(task, current->cpus_ptr); |
| task->mems_allowed = current->mems_allowed; |
| } |
| |
| struct cgroup_subsys cpuset_cgrp_subsys = { |
| .css_alloc = cpuset_css_alloc, |
| .css_online = cpuset_css_online, |
| .css_offline = cpuset_css_offline, |
| .css_free = cpuset_css_free, |
| .can_attach = cpuset_can_attach, |
| .cancel_attach = cpuset_cancel_attach, |
| .attach = cpuset_attach, |
| .post_attach = cpuset_post_attach, |
| .bind = cpuset_bind, |
| .fork = cpuset_fork, |
| .legacy_cftypes = legacy_files, |
| .dfl_cftypes = dfl_files, |
| .early_init = true, |
| .threaded = true, |
| }; |
| |
| /** |
| * cpuset_init - initialize cpusets at system boot |
| * |
| * Description: Initialize top_cpuset |
| **/ |
| |
| int __init cpuset_init(void) |
| { |
| BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL)); |
| BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL)); |
| BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL)); |
| |
| cpumask_setall(top_cpuset.cpus_allowed); |
| nodes_setall(top_cpuset.mems_allowed); |
| cpumask_setall(top_cpuset.effective_cpus); |
| nodes_setall(top_cpuset.effective_mems); |
| |
| fmeter_init(&top_cpuset.fmeter); |
| set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags); |
| top_cpuset.relax_domain_level = -1; |
| |
| BUG_ON(!alloc_cpumask_var(&cpus_attach, GFP_KERNEL)); |
| |
| return 0; |
| } |
| |
| /* |
| * If CPU and/or memory hotplug handlers, below, unplug any CPUs |
| * or memory nodes, we need to walk over the cpuset hierarchy, |
| * removing that CPU or node from all cpusets. If this removes the |
| * last CPU or node from a cpuset, then move the tasks in the empty |
| * cpuset to its next-highest non-empty parent. |
| */ |
| static void remove_tasks_in_empty_cpuset(struct cpuset *cs) |
| { |
| struct cpuset *parent; |
| |
| /* |
| * Find its next-highest non-empty parent, (top cpuset |
| * has online cpus, so can't be empty). |
| */ |
| parent = parent_cs(cs); |
| while (cpumask_empty(parent->cpus_allowed) || |
| nodes_empty(parent->mems_allowed)) |
| parent = parent_cs(parent); |
| |
| if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) { |
| pr_err("cpuset: failed to transfer tasks out of empty cpuset "); |
| pr_cont_cgroup_name(cs->css.cgroup); |
| pr_cont("\n"); |
| } |
| } |
| |
| static void |
| hotplug_update_tasks_legacy(struct cpuset *cs, |
| struct cpumask *new_cpus, nodemask_t *new_mems, |
| bool cpus_updated, bool mems_updated) |
| { |
| bool is_empty; |
| |
| spin_lock_irq(&callback_lock); |
| cpumask_copy(cs->cpus_allowed, new_cpus); |
| cpumask_copy(cs->effective_cpus, new_cpus); |
| cs->mems_allowed = *new_mems; |
| cs->effective_mems = *new_mems; |
| spin_unlock_irq(&callback_lock); |
| |
| /* |
| * Don't call update_tasks_cpumask() if the cpuset becomes empty, |
| * as the tasks will be migratecd to an ancestor. |
| */ |
| if (cpus_updated && !cpumask_empty(cs->cpus_allowed)) |
| update_tasks_cpumask(cs); |
| if (mems_updated && !nodes_empty(cs->mems_allowed)) |
| update_tasks_nodemask(cs); |
| |
| is_empty = cpumask_empty(cs->cpus_allowed) || |
| nodes_empty(cs->mems_allowed); |
| |
| mutex_unlock(&cpuset_mutex); |
| |
| /* |
| * Move tasks to the nearest ancestor with execution resources, |
| * This is full cgroup operation which will also call back into |
| * cpuset. Should be done outside any lock. |
| */ |
| if (is_empty) |
| remove_tasks_in_empty_cpuset(cs); |
| |
| mutex_lock(&cpuset_mutex); |
| } |
| |
| static void |
| 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)) |
| cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus); |
| if (nodes_empty(*new_mems)) |
| *new_mems = parent_cs(cs)->effective_mems; |
| |
| spin_lock_irq(&callback_lock); |
| cpumask_copy(cs->effective_cpus, new_cpus); |
| cs->effective_mems = *new_mems; |
| spin_unlock_irq(&callback_lock); |
| |
| if (cpus_updated) |
| update_tasks_cpumask(cs); |
| if (mems_updated) |
| update_tasks_nodemask(cs); |
| } |
| |
| static bool force_rebuild; |
| |
| void cpuset_force_rebuild(void) |
| { |
| force_rebuild = true; |
| } |
| |
| /** |
| * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug |
| * @cs: cpuset in interest |
| * @tmp: the tmpmasks structure pointer |
| * |
| * Compare @cs's cpu and mem masks against top_cpuset and if some have gone |
| * offline, update @cs accordingly. If @cs ends up with no CPU or memory, |
| * all its tasks are moved to the nearest ancestor with both resources. |
| */ |
| static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) |
| { |
| static cpumask_t new_cpus; |
| static nodemask_t new_mems; |
| bool cpus_updated; |
| bool mems_updated; |
| struct cpuset *parent; |
| retry: |
| wait_event(cpuset_attach_wq, cs->attach_in_progress == 0); |
| |
| mutex_lock(&cpuset_mutex); |
| |
| /* |
| * We have raced with task attaching. We wait until attaching |
| * is finished, so we won't attach a task to an empty cpuset. |
| */ |
| if (cs->attach_in_progress) { |
| mutex_unlock(&cpuset_mutex); |
| goto retry; |
| } |
| |
| parent = parent_cs(cs); |
| compute_effective_cpumask(&new_cpus, cs, parent); |
| nodes_and(new_mems, cs->mems_allowed, parent->effective_mems); |
| |
| if (cs->nr_subparts_cpus) |
| /* |
| * Make sure that CPUs allocated to child partitions |
| * do not show up in effective_cpus. |
| */ |
| cpumask_andnot(&new_cpus, &new_cpus, cs->subparts_cpus); |
| |
| if (!tmp || !cs->partition_root_state) |
| goto update_tasks; |
| |
| /* |
| * 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. |
| */ |
| if (is_partition_root(cs) && (cpumask_empty(&new_cpus) || |
| (parent->partition_root_state == PRS_ERROR))) { |
| if (cs->nr_subparts_cpus) { |
| cs->nr_subparts_cpus = 0; |
| cpumask_clear(cs->subparts_cpus); |
| 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; |
| } |
| 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. |
| */ |
| 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(); |
| |
| update_tasks: |
| cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus); |
| mems_updated = !nodes_equal(new_mems, cs->effective_mems); |
| |
| if (is_in_v2_mode()) |
| hotplug_update_tasks(cs, &new_cpus, &new_mems, |
| cpus_updated, mems_updated); |
| else |
| hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems, |
| cpus_updated, mems_updated); |
| |
| mutex_unlock(&cpuset_mutex); |
| } |
| |
| /** |
| * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset |
| * |
| * This function is called after either CPU or memory configuration has |
| * changed and updates cpuset accordingly. The top_cpuset is always |
| * synchronized to cpu_active_mask and N_MEMORY, which is necessary in |
| * order to make cpusets transparent (of no affect) on systems that are |
| * actively using CPU hotplug but making no active use of cpusets. |
| * |
| * Non-root cpusets are only affected by offlining. If any CPUs or memory |
| * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on |
| * all descendants. |
| * |
| * Note that CPU offlining during suspend is ignored. We don't modify |
| * cpusets across suspend/resume cycles at all. |
| */ |
| static void cpuset_hotplug_workfn(struct work_struct *work) |
| { |
| static cpumask_t new_cpus; |
| static nodemask_t new_mems; |
| bool cpus_updated, mems_updated; |
| bool on_dfl = is_in_v2_mode(); |
| struct tmpmasks tmp, *ptmp = NULL; |
| |
| if (on_dfl && !alloc_cpumasks(NULL, &tmp)) |
| ptmp = &tmp; |
| |
| mutex_lock(&cpuset_mutex); |
| |
| /* fetch the available cpus/mems and find out which changed how */ |
| cpumask_copy(&new_cpus, cpu_active_mask); |
| new_mems = node_states[N_MEMORY]; |
| |
| /* |
| * If subparts_cpus is populated, it is likely that the check below |
| * will produce a false positive on cpus_updated when the cpu list |
| * isn't changed. It is extra work, but it is better to be safe. |
| */ |
| cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus); |
| mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems); |
| |
| /* synchronize cpus_allowed to cpu_active_mask */ |
| if (cpus_updated) { |
| spin_lock_irq(&callback_lock); |
| if (!on_dfl) |
| cpumask_copy(top_cpuset.cpus_allowed, &new_cpus); |
| /* |
| * Make sure that CPUs allocated to child partitions |
| * do not show up in effective_cpus. If no CPU is left, |
| * we clear the subparts_cpus & let the child partitions |
| * fight for the CPUs again. |
| */ |
| if (top_cpuset.nr_subparts_cpus) { |
| if (cpumask_subset(&new_cpus, |
| top_cpuset.subparts_cpus)) { |
| top_cpuset.nr_subparts_cpus = 0; |
| cpumask_clear(top_cpuset.subparts_cpus); |
| } else { |
| cpumask_andnot(&new_cpus, &new_cpus, |
| top_cpuset.subparts_cpus); |
| } |
| } |
| cpumask_copy(top_cpuset.effective_cpus, &new_cpus); |
| spin_unlock_irq(&callback_lock); |
| /* we don't mess with cpumasks of tasks in top_cpuset */ |
| } |
| |
| /* synchronize mems_allowed to N_MEMORY */ |
| if (mems_updated) { |
| spin_lock_irq(&callback_lock); |
| if (!on_dfl) |
| top_cpuset.mems_allowed = new_mems; |
| top_cpuset.effective_mems = new_mems; |
| spin_unlock_irq(&callback_lock); |
| update_tasks_nodemask(&top_cpuset); |
| } |
| |
| mutex_unlock(&cpuset_mutex); |
| |
| /* if cpus or mems changed, we need to propagate to descendants */ |
| if (cpus_updated || mems_updated) { |
| struct cpuset *cs; |
| struct cgroup_subsys_state *pos_css; |
| |
| rcu_read_lock(); |
| cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) { |
| if (cs == &top_cpuset || !css_tryget_online(&cs->css)) |
| continue; |
| rcu_read_unlock(); |
| |
| cpuset_hotplug_update_tasks(cs, ptmp); |
| |
| rcu_read_lock(); |
| css_put(&cs->css); |
| } |
| rcu_read_unlock(); |
| } |
| |
| /* rebuild sched domains if cpus_allowed has changed */ |
| if (cpus_updated || force_rebuild) { |
| force_rebuild = false; |
| rebuild_sched_domains(); |
| } |
| |
| free_cpumasks(NULL, ptmp); |
| } |
| |
| void cpuset_update_active_cpus(void) |
| { |
| /* |
| * We're inside cpu hotplug critical region which usually nests |
| * inside cgroup synchronization. Bounce actual hotplug processing |
| * to a work item to avoid reverse locking order. |
| */ |
| schedule_work(&cpuset_hotplug_work); |
| } |
| |
| void cpuset_wait_for_hotplug(void) |
| { |
| flush_work(&cpuset_hotplug_work); |
| } |
| |
| /* |
| * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY]. |
| * Call this routine anytime after node_states[N_MEMORY] changes. |
| * See cpuset_update_active_cpus() for CPU hotplug handling. |
| */ |
| static int cpuset_track_online_nodes(struct notifier_block *self, |
| unsigned long action, void *arg) |
| { |
| schedule_work(&cpuset_hotplug_work); |
| return NOTIFY_OK; |
| } |
| |
| static struct notifier_block cpuset_track_online_nodes_nb = { |
| .notifier_call = cpuset_track_online_nodes, |
| .priority = 10, /* ??! */ |
| }; |
| |
| /** |
| * cpuset_init_smp - initialize cpus_allowed |
| * |
| * Description: Finish top cpuset after cpu, node maps are initialized |
| */ |
| void __init cpuset_init_smp(void) |
| { |
| cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask); |
| top_cpuset.mems_allowed = node_states[N_MEMORY]; |
| top_cpuset.old_mems_allowed = top_cpuset.mems_allowed; |
| |
| cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask); |
| top_cpuset.effective_mems = node_states[N_MEMORY]; |
| |
| register_hotmemory_notifier(&cpuset_track_online_nodes_nb); |
| |
| cpuset_migrate_mm_wq = alloc_ordered_workqueue("cpuset_migrate_mm", 0); |
| BUG_ON(!cpuset_migrate_mm_wq); |
| } |
| |
| /** |
| * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset. |
| * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed. |
| * @pmask: pointer to struct cpumask variable to receive cpus_allowed set. |
| * |
| * Description: Returns the cpumask_var_t cpus_allowed of the cpuset |
| * attached to the specified @tsk. Guaranteed to return some non-empty |
| * subset of cpu_online_mask, even if this means going outside the |
| * tasks cpuset. |
| **/ |
| |
| 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(); |
| spin_unlock_irqrestore(&callback_lock, flags); |
| } |
| |
| /** |
| * cpuset_cpus_allowed_fallback - final fallback before complete catastrophe. |
| * @tsk: pointer to task_struct with which the scheduler is struggling |
| * |
| * Description: In the case that the scheduler cannot find an allowed cpu in |
| * tsk->cpus_allowed, we fall back to task_cs(tsk)->cpus_allowed. In legacy |
| * mode however, this value is the same as task_cs(tsk)->effective_cpus, |
| * 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. |
| **/ |
| |
| void cpuset_cpus_allowed_fallback(struct task_struct *tsk) |
| { |
| rcu_read_lock(); |
| do_set_cpus_allowed(tsk, is_in_v2_mode() ? |
| task_cs(tsk)->cpus_allowed : cpu_possible_mask); |
| rcu_read_unlock(); |
| |
| /* |
| * We own tsk->cpus_allowed, nobody can change it under us. |
| * |
| * But we used cs && cs->cpus_allowed lockless and thus can |
| * race with cgroup_attach_task() or update_cpumask() and get |
| * the wrong tsk->cpus_allowed. However, both cases imply the |
| * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr() |
| * which takes task_rq_lock(). |
| * |
| * If we are called after it dropped the lock we must see all |
| * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary |
| * set any mask even if it is not right from task_cs() pov, |
| * the pending set_cpus_allowed_ptr() will fix things. |
| * |
| * select_fallback_rq() will fix things ups and set cpu_possible_mask |
| * if required. |
| */ |
| } |
| |
| void __init cpuset_init_current_mems_allowed(void) |
| { |
| nodes_setall(current->mems_allowed); |
| } |
| |
| /** |
| * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset. |
| * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed. |
| * |
| * Description: Returns the nodemask_t mems_allowed of the cpuset |
| * attached to the specified @tsk. Guaranteed to return some non-empty |
| * subset of node_states[N_MEMORY], even if this means going outside the |
| * tasks cpuset. |
| **/ |
| |
| nodemask_t cpuset_mems_allowed(struct task_struct *tsk) |
| { |
| nodemask_t mask; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&callback_lock, flags); |
| rcu_read_lock(); |
| guarantee_online_mems(task_cs(tsk), &mask); |
| rcu_read_unlock(); |
| spin_unlock_irqrestore(&callback_lock, flags); |
| |
| return mask; |
| } |
| |
| /** |
| * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed |
| * @nodemask: the nodemask to be checked |
| * |
| * Are any of the nodes in the nodemask allowed in current->mems_allowed? |
| */ |
| int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask) |
| { |
| return nodes_intersects(*nodemask, current->mems_allowed); |
| } |
| |
| /* |
| * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or |
| * mem_hardwall ancestor to the specified cpuset. Call holding |
| * callback_lock. If no ancestor is mem_exclusive or mem_hardwall |
| * (an unusual configuration), then returns the root cpuset. |
| */ |
| static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs) |
| { |
| while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs)) |
| cs = parent_cs(cs); |
| return cs; |
| } |
| |
| /** |
| * cpuset_node_allowed - Can we allocate on a memory node? |
| * @node: is this an allowed node? |
| * @gfp_mask: memory allocation flags |
| * |
| * If we're in interrupt, yes, we can always allocate. If @node is set in |
| * current's mems_allowed, yes. If it's not a __GFP_HARDWALL request and this |
| * node is set in the nearest hardwalled cpuset ancestor to current's cpuset, |
| * yes. If current has access to memory reserves as an oom victim, yes. |
| * Otherwise, no. |
| * |
| * GFP_USER allocations are marked with the __GFP_HARDWALL bit, |
| * and do not allow allocations outside the current tasks cpuset |
| * unless the task has been OOM killed. |
| * GFP_KERNEL allocations are not so marked, so can escape to the |
| * nearest enclosing hardwalled ancestor cpuset. |
| * |
| * Scanning up parent cpusets requires callback_lock. The |
| * __alloc_pages() routine only calls here with __GFP_HARDWALL bit |
| * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the |
| * current tasks mems_allowed came up empty on the first pass over |
| * the zonelist. So only GFP_KERNEL allocations, if all nodes in the |
| * cpuset are short of memory, might require taking the callback_lock. |
| * |
| * The first call here from mm/page_alloc:get_page_from_freelist() |
| * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets, |
| * so no allocation on a node outside the cpuset is allowed (unless |
| * in interrupt, of course). |
| * |
| * The second pass through get_page_from_freelist() doesn't even call |
| * here for GFP_ATOMIC calls. For those calls, the __alloc_pages() |
| * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set |
| * in alloc_flags. That logic and the checks below have the combined |
| * affect that: |
| * in_interrupt - any node ok (current task context irrelevant) |
| * GFP_ATOMIC - any node ok |
| * tsk_is_oom_victim - any node ok |
| * GFP_KERNEL - any node in enclosing hardwalled cpuset ok |
| * GFP_USER - only nodes in current tasks mems allowed ok. |
| */ |
| bool __cpuset_node_allowed(int node, gfp_t gfp_mask) |
| { |
| struct cpuset *cs; /* current cpuset ancestors */ |
| int allowed; /* is allocation in zone z allowed? */ |
| unsigned long flags; |
| |
| if (in_interrupt()) |
| return true; |
| if (node_isset(node, current->mems_allowed)) |
| return true; |
| /* |
| * Allow tasks that have access to memory reserves because they have |
| * been OOM killed to get memory anywhere. |
| */ |
| if (unlikely(tsk_is_oom_victim(current))) |
| return true; |
| if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */ |
| return false; |
| |
| if (current->flags & PF_EXITING) /* Let dying task have memory */ |
| return true; |
| |
| /* Not hardwall and node outside mems_allowed: scan up cpusets */ |
| spin_lock_irqsave(&callback_lock, flags); |
| |
| rcu_read_lock(); |
| cs = nearest_hardwall_ancestor(task_cs(current)); |
| allowed = node_isset(node, cs->mems_allowed); |
| rcu_read_unlock(); |
| |
| spin_unlock_irqrestore(&callback_lock, flags); |
| return allowed; |
| } |
| |
| /** |
| * cpuset_mem_spread_node() - On which node to begin search for a file page |
| * cpuset_slab_spread_node() - On which node to begin search for a slab page |
| * |
| * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for |
| * tasks in a cpuset with is_spread_page or is_spread_slab set), |
| * and if the memory allocation used cpuset_mem_spread_node() |
| * to determine on which node to start looking, as it will for |
| * certain page cache or slab cache pages such as used for file |
| * system buffers and inode caches, then instead of starting on the |
| * local node to look for a free page, rather spread the starting |
| * node around the tasks mems_allowed nodes. |
| * |
| * We don't have to worry about the returned node being offline |
| * because "it can't happen", and even if it did, it would be ok. |
| * |
| * The routines calling guarantee_online_mems() are careful to |
| * only set nodes in task->mems_allowed that are online. So it |
| * should not be possible for the following code to return an |
| * offline node. But if it did, that would be ok, as this routine |
| * is not returning the node where the allocation must be, only |
| * the node where the search should start. The zonelist passed to |
| * __alloc_pages() will include all nodes. If the slab allocator |
| * is passed an offline node, it will fall back to the local node. |
| * See kmem_cache_alloc_node(). |
| */ |
| |
| static int cpuset_spread_node(int *rotor) |
| { |
| return *rotor = next_node_in(*rotor, current->mems_allowed); |
| } |
| |
| int cpuset_mem_spread_node(void) |
|