--- /dev/null
+/*
+ * 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/namei.h>
+#include <linux/pagemap.h>
+#include <linux/proc_fs.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.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/backing-dev.h>
+#include <linux/sort.h>
+
+#include <asm/uaccess.h>
+#include <linux/atomic.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+#include <linux/cgroup.h>
+#include <linux/wait.h>
+
+struct static_key cpusets_enabled_key __read_mostly = STATIC_KEY_INIT_FALSE;
+
+/* See "Frequency meter" comments, below. */
+
+struct fmeter {
+ int cnt; /* unprocessed events count */
+ int val; /* most recent output value */
+ time_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;
+
+ /*
+ * 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;
+};
+
+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);
+}
+
+#ifdef CONFIG_NUMA
+static inline bool task_has_mempolicy(struct task_struct *task)
+{
+ return task->mempolicy;
+}
+#else
+static inline bool task_has_mempolicy(struct task_struct *task)
+{
+ return false;
+}
+#endif
+
+
+/* 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(const struct cpuset *cs)
+{
+ return test_bit(CS_ONLINE, &cs->flags);
+}
+
+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 struct cpuset top_cpuset = {
+ .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
+ (1 << CS_MEM_EXCLUSIVE)),
+};
+
+/**
+ * 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);
+
+/*
+ * 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);
+
+/*
+ * This is ugly, but preserves the userspace API for existing cpuset
+ * users. If someone tries to mount the "cpuset" filesystem, we
+ * silently switch it to mount "cgroup" instead
+ */
+static struct dentry *cpuset_mount(struct file_system_type *fs_type,
+ int flags, const char *unused_dev_name, void *data)
+{
+ struct file_system_type *cgroup_fs = get_fs_type("cgroup");
+ struct dentry *ret = ERR_PTR(-ENODEV);
+ if (cgroup_fs) {
+ char mountopts[] =
+ "cpuset,noprefix,"
+ "release_agent=/sbin/cpuset_release_agent";
+ ret = cgroup_fs->mount(cgroup_fs, flags,
+ unused_dev_name, mountopts);
+ put_filesystem(cgroup_fs);
+ }
+ return ret;
+}
+
+static struct file_system_type cpuset_fs_type = {
+ .name = "cpuset",
+ .mount = cpuset_mount,
+};
+
+/*
+ * 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. The top
+ * cpuset always has some cpus online.
+ *
+ * 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);
+ 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_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_cpumask_var(&trial->cpus_allowed, GFP_KERNEL))
+ goto free_cs;
+ if (!alloc_cpumask_var(&trial->effective_cpus, GFP_KERNEL))
+ goto free_cpus;
+
+ cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
+ cpumask_copy(trial->effective_cpus, cs->effective_cpus);
+ return trial;
+
+free_cpus:
+ free_cpumask_var(trial->cpus_allowed);
+free_cs:
+ kfree(trial);
+ return NULL;
+}
+
+/**
+ * free_trial_cpuset - free the trial cpuset
+ * @trial: the trial cpuset to be freed
+ */
+static void free_trial_cpuset(struct cpuset *trial)
+{
+ free_cpumask_var(trial->effective_cpus);
+ free_cpumask_var(trial->cpus_allowed);
+ kfree(trial);
+}
+
+/*
+ * 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 (!cgroup_on_dfl(cur->css.cgroup) && !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_has_tasks(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();
+}
+
+/*
+ * 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/cgroups/cpusets.txt
+ * 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:
+ * q - a linked-list queue of cpuset pointers, used to implement a
+ * top-down scan of all cpusets. This scan loads a pointer
+ * to each cpuset marked is_sched_load_balance into the
+ * array 'csa'. 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; /* scans q */
+ 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 */
+ cpumask_var_t non_isolated_cpus; /* load balanced CPUs */
+ 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;
+
+ doms = NULL;
+ dattr = NULL;
+ csa = NULL;
+
+ if (!alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL))
+ goto done;
+ cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
+
+ /* Special case for the 99% of systems with one, full, sched domain */
+ if (is_sched_load_balance(&top_cpuset)) {
+ 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,
+ non_isolated_cpus);
+
+ goto done;
+ }
+
+ csa = kmalloc(nr_cpusets() * sizeof(cp), GFP_KERNEL);
+ if (!csa)
+ goto done;
+ csn = 0;
+
+ rcu_read_lock();
+ 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 (!cpumask_empty(cp->cpus_allowed) &&
+ !(is_sched_load_balance(cp) &&
+ cpumask_intersects(cp->cpus_allowed, non_isolated_cpus)))
+ continue;
+
+ if (is_sched_load_balance(cp))
+ csa[csn++] = cp;
+
+ /* skip @cp's subtree */
+ 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(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, non_isolated_cpus);
+ if (dattr)
+ update_domain_attr_tree(dattr + nslot, b);
+
+ /* Done with this partition */
+ b->pn = -1;
+ }
+ }
+ nslot++;
+ }
+ BUG_ON(nslot != ndoms);
+
+done:
+ free_cpumask_var(non_isolated_cpus);
+ 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 (!cpumask_equal(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, &it);
+ while ((task = css_task_iter_next(&it)))
+ set_cpus_allowed_ptr(task, cs->effective_cpus);
+ css_task_iter_end(&it);
+}
+
+/*
+ * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
+ * @cs: the cpuset to consider
+ * @new_cpus: temp variable for calculating new effective_cpus
+ *
+ * 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 cpumask *new_cpus)
+{
+ 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);
+
+ cpumask_and(new_cpus, cp->cpus_allowed, parent->effective_cpus);
+
+ /*
+ * If it becomes empty, inherit the effective mask of the
+ * parent, which is guaranteed to have some CPUs.
+ */
+ if (cgroup_on_dfl(cp->css.cgroup) && cpumask_empty(new_cpus))
+ cpumask_copy(new_cpus, parent->effective_cpus);
+
+ /* Skip the whole subtree if the cpumask remains the same. */
+ if (cpumask_equal(new_cpus, cp->effective_cpus)) {
+ pos_css = css_rightmost_descendant(pos_css);
+ continue;
+ }
+
+ if (!css_tryget_online(&cp->css))
+ continue;
+ rcu_read_unlock();
+
+ spin_lock_irq(&callback_lock);
+ cpumask_copy(cp->effective_cpus, new_cpus);
+ spin_unlock_irq(&callback_lock);
+
+ WARN_ON(!cgroup_on_dfl(cp->css.cgroup) &&
+ !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
+
+ update_tasks_cpumask(cp);
+
+ /*
+ * If the effective cpumask of any non-empty cpuset is changed,
+ * we need to rebuild sched domains.
+ */
+ if (!cpumask_empty(cp->cpus_allowed) &&
+ is_sched_load_balance(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_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;
+
+ /* 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;
+
+ spin_lock_irq(&callback_lock);
+ cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
+ spin_unlock_irq(&callback_lock);
+
+ /* use trialcs->cpus_allowed as a temp variable */
+ update_cpumasks_hier(cs, trialcs->cpus_allowed);
+ return 0;
+}
+
+/*
+ * cpuset_migrate_mm
+ *
+ * Migrate memory region from one set of nodes to another.
+ *
+ * Temporarilly set tasks mems_allowed to target nodes of migration,
+ * so that the migration code can allocate pages on these nodes.
+ *
+ * While the mm_struct we are migrating is typically from some
+ * other task, the task_struct mems_allowed that we are hacking
+ * is for our current task, which must allocate new pages for that
+ * migrating memory region.
+ */
+
+static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
+ const nodemask_t *to)
+{
+ struct task_struct *tsk = current;
+
+ tsk->mems_allowed = *to;
+
+ do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
+
+ rcu_read_lock();
+ guarantee_online_mems(task_cs(tsk), &tsk->mems_allowed);
+ rcu_read_unlock();
+}
+
+/*
+ * 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
+ *
+ * In order to avoid seeing no nodes if the old and new nodes are disjoint,
+ * we structure updates as setting all new allowed nodes, then clearing newly
+ * disallowed ones.
+ */
+static void cpuset_change_task_nodemask(struct task_struct *tsk,
+ nodemask_t *newmems)
+{
+ bool need_loop;
+
+ /*
+ * Allow tasks that have access to memory reserves because they have
+ * been OOM killed to get memory anywhere.
+ */
+ if (unlikely(test_thread_flag(TIF_MEMDIE)))
+ return;
+ if (current->flags & PF_EXITING) /* Let dying task have memory */
+ return;
+
+ task_lock(tsk);
+ /*
+ * Determine if a loop is necessary if another thread is doing
+ * read_mems_allowed_begin(). If at least one node remains unchanged and
+ * tsk does not have a mempolicy, then an empty nodemask will not be
+ * possible when mems_allowed is larger than a word.
+ */
+ need_loop = task_has_mempolicy(tsk) ||
+ !nodes_intersects(*newmems, tsk->mems_allowed);
+
+ if (need_loop) {
+ local_irq_disable();
+ write_seqcount_begin(&tsk->mems_allowed_seq);
+ }
+
+ nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
+ mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
+
+ mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
+ tsk->mems_allowed = *newmems;
+
+ if (need_loop) {
+ 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, &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);
+ 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 (cgroup_on_dfl(cp->css.cgroup) && 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(!cgroup_on_dfl(cp->css.cgroup) &&
+ !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, &cs->mems_allowed);
+done:
+ return retval;
+}
+
+int current_cpuset_is_being_rebound(void)
+{
+ int 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, &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_trial_cpuset(trialcs);
+ 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 ((time_t)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)
+{
+ time_t now = get_seconds();
+ time_t 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_subsys_state *css,
+ struct cgroup_taskset *tset)
+{
+ struct cpuset *cs = css_cs(css);
+ struct task_struct *task;
+ int ret;
+
+ /* used later by cpuset_attach() */
+ cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset));
+
+ mutex_lock(&cpuset_mutex);
+
+ /* allow moving tasks into an empty cpuset if on default hierarchy */
+ ret = -ENOSPC;
+ if (!cgroup_on_dfl(css->cgroup) &&
+ (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
+ goto out_unlock;
+
+ cgroup_taskset_for_each(task, 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_subsys_state *css,
+ struct cgroup_taskset *tset)
+{
+ 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_subsys_state *css,
+ struct cgroup_taskset *tset)
+{
+ /* static buf protected by cpuset_mutex */
+ static nodemask_t cpuset_attach_nodemask_to;
+ struct mm_struct *mm;
+ struct task_struct *task;
+ struct task_struct *leader = cgroup_taskset_first(tset);
+ struct cpuset *cs = css_cs(css);
+ struct cpuset *oldcs = cpuset_attach_old_cs;
+
+ 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, 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, possibly for multiple threads in a threadgroup. This is
+ * expensive and may sleep.
+ */
+ cpuset_attach_nodemask_to = cs->effective_mems;
+ 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);
+ }
+ 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_CPU_EXCLUSIVE,
+ FILE_MEM_EXCLUSIVE,
+ FILE_MEM_HARDWALL,
+ FILE_SCHED_LOAD_BALANCE,
+ 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_MEMORY_PRESSURE:
+ retval = -EACCES;
+ 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_trial_cpuset(trialcs);
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ kernfs_unbreak_active_protection(of->kn);
+ css_put(&cs->css);
+ 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;
+ 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;
+}
+
+
+/*
+ * for the common functions, 'private' gives the type of file
+ */
+
+static struct cftype 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,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_MEMORY_PRESSURE,
+ .mode = S_IRUGO,
+ },
+
+ {
+ .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 */
+};
+
+/*
+ * 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_cpumask_var(&cs->cpus_allowed, GFP_KERNEL))
+ goto free_cs;
+ if (!alloc_cpumask_var(&cs->effective_cpus, GFP_KERNEL))
+ goto free_cpus;
+
+ set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+ cpumask_clear(cs->cpus_allowed);
+ nodes_clear(cs->mems_allowed);
+ cpumask_clear(cs->effective_cpus);
+ nodes_clear(cs->effective_mems);
+ fmeter_init(&cs->fmeter);
+ cs->relax_domain_level = -1;
+
+ return &cs->css;
+
+free_cpus:
+ free_cpumask_var(cs->cpus_allowed);
+free_cs:
+ kfree(cs);
+ return ERR_PTR(-ENOMEM);
+}
+
+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 (cgroup_on_dfl(cs->css.cgroup)) {
+ cpumask_copy(cs->effective_cpus, parent->effective_cpus);
+ cs->effective_mems = parent->effective_mems;
+ }
+ 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().
+ */
+
+static void cpuset_css_offline(struct cgroup_subsys_state *css)
+{
+ struct cpuset *cs = css_cs(css);
+
+ mutex_lock(&cpuset_mutex);
+
+ if (is_sched_load_balance(cs))
+ update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
+
+ 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_cpumask_var(cs->effective_cpus);
+ free_cpumask_var(cs->cpus_allowed);
+ kfree(cs);
+}
+
+static void cpuset_bind(struct cgroup_subsys_state *root_css)
+{
+ mutex_lock(&cpuset_mutex);
+ spin_lock_irq(&callback_lock);
+
+ if (cgroup_on_dfl(root_css->cgroup)) {
+ 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);
+}
+
+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,
+ .bind = cpuset_bind,
+ .legacy_cftypes = files,
+ .early_init = 1,
+};
+
+/**
+ * cpuset_init - initialize cpusets at system boot
+ *
+ * Description: Initialize top_cpuset and the cpuset internal file system,
+ **/
+
+int __init cpuset_init(void)
+{
+ int err = 0;
+
+ if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
+ BUG();
+ if (!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL))
+ BUG();
+
+ 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;
+
+ err = register_filesystem(&cpuset_fs_type);
+ if (err < 0)
+ return err;
+
+ if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
+ BUG();
+
+ 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);
+}
+
+/**
+ * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
+ * @cs: cpuset in interest
+ *
+ * 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)
+{
+ static cpumask_t new_cpus;
+ static nodemask_t new_mems;
+ bool cpus_updated;
+ bool mems_updated;
+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;
+ }
+
+ cpumask_and(&new_cpus, cs->cpus_allowed, parent_cs(cs)->effective_cpus);
+ nodes_and(new_mems, cs->mems_allowed, parent_cs(cs)->effective_mems);
+
+ cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
+ mems_updated = !nodes_equal(new_mems, cs->effective_mems);
+
+ if (cgroup_on_dfl(cs->css.cgroup))
+ 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 = cgroup_on_dfl(top_cpuset.css.cgroup);
+
+ 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];
+
+ 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);
+ 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);
+
+ rcu_read_lock();
+ css_put(&cs->css);
+ }
+ rcu_read_unlock();
+ }
+
+ /* rebuild sched domains if cpus_allowed has changed */
+ if (cpus_updated)
+ rebuild_sched_domains();
+}
+
+void cpuset_update_active_cpus(bool cpu_online)
+{
+ /*
+ * 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.
+ *
+ * We still need to do partition_sched_domains() synchronously;
+ * otherwise, the scheduler will get confused and put tasks to the
+ * dead CPU. Fall back to the default single domain.
+ * cpuset_hotplug_workfn() will rebuild it as necessary.
+ */
+ partition_sched_domains(1, NULL, NULL);
+ schedule_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_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);
+}
+
+void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
+{
+ rcu_read_lock();
+ do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
+ 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 due to TIF_MEMDIE, 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 as is marked TIF_MEMDIE.
+ * 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
+ * TIF_MEMDIE - any node ok
+ * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
+ * GFP_USER - only nodes in current tasks mems allowed ok.
+ */
+int __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 1;
+ if (node_isset(node, current->mems_allowed))
+ return 1;
+ /*
+ * Allow tasks that have access to memory reserves because they have
+ * been OOM killed to get memory anywhere.
+ */
+ if (unlikely(test_thread_flag(TIF_MEMDIE)))
+ return 1;
+ if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
+ return 0;
+
+ if (current->flags & PF_EXITING) /* Let dying task have memory */
+ return 1;
+
+ /* 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)
+{
+ int node;
+
+ node = next_node(*rotor, current->mems_allowed);
+ if (node == MAX_NUMNODES)
+ node = first_node(current->mems_allowed);
+ *rotor = node;
+ return node;
+}
+
+int cpuset_mem_spread_node(void)
+{
+ if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
+ current->cpuset_mem_spread_rotor =
+ node_random(¤t->mems_allowed);
+
+ return cpuset_spread_node(¤t->cpuset_mem_spread_rotor);
+}
+
+int cpuset_slab_spread_node(void)
+{
+ if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
+ current->cpuset_slab_spread_rotor =
+ node_random(¤t->mems_allowed);
+
+ return cpuset_spread_node(¤t->cpuset_slab_spread_rotor);
+}
+
+EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
+
+/**
+ * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
+ * @tsk1: pointer to task_struct of some task.
+ * @tsk2: pointer to task_struct of some other task.
+ *
+ * Description: Return true if @tsk1's mems_allowed intersects the
+ * mems_allowed of @tsk2. Used by the OOM killer to determine if
+ * one of the task's memory usage might impact the memory available
+ * to the other.
+ **/
+
+int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
+ const struct task_struct *tsk2)
+{
+ return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
+}
+
+/**
+ * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
+ * @tsk: pointer to task_struct of some task.
+ *
+ * Description: Prints @task's name, cpuset name, and cached copy of its
+ * mems_allowed to the kernel log.
+ */
+void cpuset_print_task_mems_allowed(struct task_struct *tsk)
+{
+ struct cgroup *cgrp;
+
+ rcu_read_lock();
+
+ cgrp = task_cs(tsk)->css.cgroup;
+ pr_info("%s cpuset=", tsk->comm);
+ pr_cont_cgroup_name(cgrp);
+ pr_cont(" mems_allowed=%*pbl\n", nodemask_pr_args(&tsk->mems_allowed));
+
+ rcu_read_unlock();
+}
+
+/*
+ * Collection of memory_pressure is suppressed unless
+ * this flag is enabled by writing "1" to the special
+ * cpuset file 'memory_pressure_enabled' in the root cpuset.
+ */
+
+int cpuset_memory_pressure_enabled __read_mostly;
+
+/**
+ * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
+ *
+ * Keep a running average of the rate of synchronous (direct)
+ * page reclaim efforts initiated by tasks in each cpuset.
+ *
+ * This represents the rate at which some task in the cpuset
+ * ran low on memory on all nodes it was allowed to use, and
+ * had to enter the kernels page reclaim code in an effort to
+ * create more free memory by tossing clean pages or swapping
+ * or writing dirty pages.
+ *
+ * Display to user space in the per-cpuset read-only file
+ * "memory_pressure". Value displayed is an integer
+ * representing the recent rate of entry into the synchronous
+ * (direct) page reclaim by any task attached to the cpuset.
+ **/
+
+void __cpuset_memory_pressure_bump(void)
+{
+ rcu_read_lock();
+ fmeter_markevent(&task_cs(current)->fmeter);
+ rcu_read_unlock();
+}
+
+#ifdef CONFIG_PROC_PID_CPUSET
+/*
+ * proc_cpuset_show()
+ * - Print tasks cpuset path into seq_file.
+ * - Used for /proc/<pid>/cpuset.
+ * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
+ * doesn't really matter if tsk->cpuset changes after we read it,
+ * and we take cpuset_mutex, keeping cpuset_attach() from changing it
+ * anyway.
+ */
+int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk)
+{
+ char *buf, *p;
+ struct cgroup_subsys_state *css;
+ int retval;
+
+ retval = -ENOMEM;
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!buf)
+ goto out;
+
+ retval = -ENAMETOOLONG;
+ rcu_read_lock();
+ css = task_css(tsk, cpuset_cgrp_id);
+ p = cgroup_path(css->cgroup, buf, PATH_MAX);
+ rcu_read_unlock();
+ if (!p)
+ goto out_free;
+ seq_puts(m, p);
+ seq_putc(m, '\n');
+ retval = 0;
+out_free:
+ kfree(buf);
+out:
+ return retval;
+}
+#endif /* CONFIG_PROC_PID_CPUSET */
+
+/* Display task mems_allowed in /proc/<pid>/status file. */
+void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
+{
+ seq_printf(m, "Mems_allowed:\t%*pb\n",
+ nodemask_pr_args(&task->mems_allowed));
+ seq_printf(m, "Mems_allowed_list:\t%*pbl\n",
+ nodemask_pr_args(&task->mems_allowed));
+}
Code Review / kvmfornfv.git / blobdiff