diff options
Diffstat (limited to 'kernel/cpuset.c')
| -rw-r--r-- | kernel/cpuset.c | 2467 |
1 files changed, 2467 insertions, 0 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c new file mode 100644 index 0000000..96c0ba1 --- /dev/null +++ b/kernel/cpuset.c @@ -0,0 +1,2467 @@ +/* + * 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/module.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 <asm/atomic.h> +#include <linux/mutex.h> +#include <linux/workqueue.h> +#include <linux/cgroup.h> + +/* + * Tracks how many cpusets are currently defined in system. + * When there is only one cpuset (the root cpuset) we can + * short circuit some hooks. + */ +int number_of_cpusets __read_mostly; + +/* Forward declare cgroup structures */ +struct cgroup_subsys cpuset_subsys; +struct cpuset; + +/* 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 */ + cpumask_t cpus_allowed; /* CPUs allowed to tasks in cpuset */ + nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */ + + struct cpuset *parent; /* my parent */ + + /* + * Copy of global cpuset_mems_generation as of the most + * recent time this cpuset changed its mems_allowed. + */ + int mems_generation; + + struct fmeter fmeter; /* memory_pressure filter */ + + /* partition number for rebuild_sched_domains() */ + int pn; + + /* for custom sched domain */ + int relax_domain_level; + + /* used for walking a cpuset heirarchy */ + struct list_head stack_list; +}; + +/* Retrieve the cpuset for a cgroup */ +static inline struct cpuset *cgroup_cs(struct cgroup *cont) +{ + return container_of(cgroup_subsys_state(cont, cpuset_subsys_id), + struct cpuset, css); +} + +/* Retrieve the cpuset for a task */ +static inline struct cpuset *task_cs(struct task_struct *task) +{ + return container_of(task_subsys_state(task, cpuset_subsys_id), + struct cpuset, css); +} +struct cpuset_hotplug_scanner { + struct cgroup_scanner scan; + struct cgroup *to; +}; + +/* bits in struct cpuset flags field */ +typedef enum { + 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 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); +} + +/* + * Increment this integer everytime any cpuset changes its + * mems_allowed value. Users of cpusets can track this generation + * number, and avoid having to lock and reload mems_allowed unless + * the cpuset they're using changes generation. + * + * A single, global generation is needed because cpuset_attach_task() could + * reattach a task to a different cpuset, which must not have its + * generation numbers aliased with those of that tasks previous cpuset. + * + * Generations are needed for mems_allowed because one task cannot + * modify another's memory placement. So we must enable every task, + * on every visit to __alloc_pages(), to efficiently check whether + * its current->cpuset->mems_allowed has changed, requiring an update + * of its current->mems_allowed. + * + * Since writes to cpuset_mems_generation are guarded by the cgroup lock + * there is no need to mark it atomic. + */ +static int cpuset_mems_generation; + +static struct cpuset top_cpuset = { + .flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)), + .cpus_allowed = CPU_MASK_ALL, + .mems_allowed = NODE_MASK_ALL, +}; + +/* + * There are two global mutexes guarding cpuset structures. The first + * is the main control groups cgroup_mutex, accessed via + * cgroup_lock()/cgroup_unlock(). The second is the cpuset-specific + * callback_mutex, below. They can nest. It is ok to first take + * cgroup_mutex, then nest callback_mutex. 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 mutexes to modify cpusets. If a task + * holds cgroup_mutex, then it blocks others wanting that mutex, + * ensuring that it is the only task able to also acquire callback_mutex + * 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 cgroup_mutex. While it is + * performing these checks, various callback routines can briefly + * acquire callback_mutex to query cpusets. Once it is ready to make + * the changes, it takes callback_mutex, blocking everyone else. + * + * Calls to the kernel memory allocator can not be made while holding + * callback_mutex, as that would risk double tripping on callback_mutex + * from one of the callbacks into the cpuset code from within + * __alloc_pages(). + * + * If a task is only holding callback_mutex, then it has read-only + * access to cpusets. + * + * The task_struct fields mems_allowed and mems_generation may only + * be accessed in the context of that task, so require no locks. + * + * The cpuset_common_file_read() handlers only hold callback_mutex 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(callback_mutex); + +/* + * 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 int cpuset_get_sb(struct file_system_type *fs_type, + int flags, const char *unused_dev_name, + void *data, struct vfsmount *mnt) +{ + struct file_system_type *cgroup_fs = get_fs_type("cgroup"); + int ret = -ENODEV; + if (cgroup_fs) { + char mountopts[] = + "cpuset,noprefix," + "release_agent=/sbin/cpuset_release_agent"; + ret = cgroup_fs->get_sb(cgroup_fs, flags, + unused_dev_name, mountopts, mnt); + put_filesystem(cgroup_fs); + } + return ret; +} + +static struct file_system_type cpuset_fs_type = { + .name = "cpuset", + .get_sb = cpuset_get_sb, +}; + +/* + * 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. If we get + * all the way to the top and still haven't found any online cpus, + * return cpu_online_map. Or if passed a NULL cs from an exit'ing + * task, return cpu_online_map. + * + * One way or another, we guarantee to return some non-empty subset + * of cpu_online_map. + * + * Call with callback_mutex held. + */ + +static void guarantee_online_cpus(const struct cpuset *cs, cpumask_t *pmask) +{ + while (cs && !cpus_intersects(cs->cpus_allowed, cpu_online_map)) + cs = cs->parent; + if (cs) + cpus_and(*pmask, cs->cpus_allowed, cpu_online_map); + else + *pmask = cpu_online_map; + BUG_ON(!cpus_intersects(*pmask, cpu_online_map)); +} + +/* + * 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. If we get all the way to the top and still haven't + * found any online mems, return node_states[N_HIGH_MEMORY]. + * + * One way or another, we guarantee to return some non-empty subset + * of node_states[N_HIGH_MEMORY]. + * + * Call with callback_mutex held. + */ + +static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask) +{ + while (cs && !nodes_intersects(cs->mems_allowed, + node_states[N_HIGH_MEMORY])) + cs = cs->parent; + if (cs) + nodes_and(*pmask, cs->mems_allowed, + node_states[N_HIGH_MEMORY]); + else + *pmask = node_states[N_HIGH_MEMORY]; + BUG_ON(!nodes_intersects(*pmask, node_states[N_HIGH_MEMORY])); +} + +/** + * cpuset_update_task_memory_state - update task memory placement + * + * If the current tasks cpusets mems_allowed changed behind our + * backs, update current->mems_allowed, mems_generation and task NUMA + * mempolicy to the new value. + * + * Task mempolicy is updated by rebinding it relative to the + * current->cpuset if a task has its memory placement changed. + * Do not call this routine if in_interrupt(). + * + * Call without callback_mutex or task_lock() held. May be + * called with or without cgroup_mutex held. Thanks in part to + * 'the_top_cpuset_hack', the task's cpuset pointer will never + * be NULL. This routine also might acquire callback_mutex during + * call. + * + * Reading current->cpuset->mems_generation doesn't need task_lock + * to guard the current->cpuset derefence, because it is guarded + * from concurrent freeing of current->cpuset using RCU. + * + * The rcu_dereference() is technically probably not needed, + * as I don't actually mind if I see a new cpuset pointer but + * an old value of mems_generation. However this really only + * matters on alpha systems using cpusets heavily. If I dropped + * that rcu_dereference(), it would save them a memory barrier. + * For all other arch's, rcu_dereference is a no-op anyway, and for + * alpha systems not using cpusets, another planned optimization, + * avoiding the rcu critical section for tasks in the root cpuset + * which is statically allocated, so can't vanish, will make this + * irrelevant. Better to use RCU as intended, than to engage in + * some cute trick to save a memory barrier that is impossible to + * test, for alpha systems using cpusets heavily, which might not + * even exist. + * + * This routine is needed to update the per-task mems_allowed data, + * within the tasks context, when it is trying to allocate memory + * (in various mm/mempolicy.c routines) and notices that some other + * task has been modifying its cpuset. + */ + +void cpuset_update_task_memory_state(void) +{ + int my_cpusets_mem_gen; + struct task_struct *tsk = current; + struct cpuset *cs; + + if (task_cs(tsk) == &top_cpuset) { + /* Don't need rcu for top_cpuset. It's never freed. */ + my_cpusets_mem_gen = top_cpuset.mems_generation; + } else { + rcu_read_lock(); + my_cpusets_mem_gen = task_cs(tsk)->mems_generation; + rcu_read_unlock(); + } + + if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) { + mutex_lock(&callback_mutex); + task_lock(tsk); + cs = task_cs(tsk); /* Maybe changed when task not locked */ + guarantee_online_mems(cs, &tsk->mems_allowed); + tsk->cpuset_mems_generation = cs->mems_generation; + if (is_spread_page(cs)) + tsk->flags |= PF_SPREAD_PAGE; + else + tsk->flags &= ~PF_SPREAD_PAGE; + if (is_spread_slab(cs)) + tsk->flags |= PF_SPREAD_SLAB; + else + tsk->flags &= ~PF_SPREAD_SLAB; + task_unlock(tsk); + mutex_unlock(&callback_mutex); + mpol_rebind_task(tsk, &tsk->mems_allowed); + } +} + +/* + * 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 cgroup_mutex. + */ + +static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q) +{ + return cpus_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); +} + +/* + * 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 + * cgroup_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(const struct cpuset *cur, const struct cpuset *trial) +{ + struct cgroup *cont; + struct cpuset *c, *par; + + /* Each of our child cpusets must be a subset of us */ + list_for_each_entry(cont, &cur->css.cgroup->children, sibling) { + if (!is_cpuset_subset(cgroup_cs(cont), trial)) + return -EBUSY; + } + + /* Remaining checks don't apply to root cpuset */ + if (cur == &top_cpuset) + return 0; + + par = cur->parent; + + /* We must be a subset of our parent cpuset */ + if (!is_cpuset_subset(trial, par)) + return -EACCES; + + /* + * If either I or some sibling (!= me) is exclusive, we can't + * overlap + */ + list_for_each_entry(cont, &par->css.cgroup->children, sibling) { + c = cgroup_cs(cont); + if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) && + c != cur && + cpus_intersects(trial->cpus_allowed, c->cpus_allowed)) + return -EINVAL; + if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) && + c != cur && + nodes_intersects(trial->mems_allowed, c->mems_allowed)) + return -EINVAL; + } + + /* Cpusets with tasks can't have empty cpus_allowed or mems_allowed */ + if (cgroup_task_count(cur->css.cgroup)) { + if (cpus_empty(trial->cpus_allowed) || + nodes_empty(trial->mems_allowed)) { + return -ENOSPC; + } + } + + return 0; +} + +/* + * Helper routine for generate_sched_domains(). + * Do cpusets a, b have overlapping cpus_allowed masks? + */ +static int cpusets_overlap(struct cpuset *a, struct cpuset *b) +{ + return cpus_intersects(a->cpus_allowed, b->cpus_allowed); +} + +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 *c) +{ + LIST_HEAD(q); + + list_add(&c->stack_list, &q); + while (!list_empty(&q)) { + struct cpuset *cp; + struct cgroup *cont; + struct cpuset *child; + + cp = list_first_entry(&q, struct cpuset, stack_list); + list_del(q.next); + + if (cpus_empty(cp->cpus_allowed)) + continue; + + if (is_sched_load_balance(cp)) + update_domain_attr(dattr, cp); + + list_for_each_entry(cont, &cp->css.cgroup->children, sibling) { + child = cgroup_cs(cont); + list_add_tail(&child->stack_list, &q); + } + } +} + +/* + * 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.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/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 cgroup_lock 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.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_t **domains, + struct sched_domain_attr **attributes) +{ + LIST_HEAD(q); /* queue of cpusets to be scanned */ + 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_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[] cpumask_t slot */ + + doms = NULL; + dattr = NULL; + csa = NULL; + + /* Special case for the 99% of systems with one, full, sched domain */ + if (is_sched_load_balance(&top_cpuset)) { + doms = kmalloc(sizeof(cpumask_t), GFP_KERNEL); + 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); + } + *doms = top_cpuset.cpus_allowed; + + ndoms = 1; + goto done; + } + + csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL); + if (!csa) + goto done; + csn = 0; + + list_add(&top_cpuset.stack_list, &q); + while (!list_empty(&q)) { + struct cgroup *cont; + struct cpuset *child; /* scans child cpusets of cp */ + + cp = list_first_entry(&q, struct cpuset, stack_list); + list_del(q.next); + + if (cpus_empty(cp->cpus_allowed)) + continue; + + /* + * 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 (is_sched_load_balance(cp)) { + csa[csn++] = cp; + continue; + } + + list_for_each_entry(cont, &cp->css.cgroup->children, sibling) { + child = cgroup_cs(cont); + list_add_tail(&child->stack_list, &q); + } + } + + 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 = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL); + 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]; + cpumask_t *dp; + int apn = a->pn; + + if (apn < 0) { + /* Skip completed partitions */ + continue; + } + + dp = doms + nslot; + + if (nslot == ndoms) { + static int warnings = 10; + if (warnings) { + printk(KERN_WARNING + "rebuild_sched_domains confused:" + " nslot %d, ndoms %d, csn %d, i %d," + " apn %d\n", + nslot, ndoms, csn, i, apn); + warnings--; + } + continue; + } + + cpus_clear(*dp); + if (dattr) + *(dattr + nslot) = SD_ATTR_INIT; + for (j = i; j < csn; j++) { + struct cpuset *b = csa[j]; + + if (apn == b->pn) { + cpus_or(*dp, *dp, b->cpus_allowed); + 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. + * + * Call with neither cgroup_mutex held nor within get_online_cpus(). + * Takes both cgroup_mutex and get_online_cpus(). + * + * Cannot be directly called from cpuset code handling changes + * to the cpuset pseudo-filesystem, because it cannot be called + * from code that already holds cgroup_mutex. + */ +static void do_rebuild_sched_domains(struct work_struct *unused) +{ + struct sched_domain_attr *attr; + cpumask_t *doms; + int ndoms; + + get_online_cpus(); + + /* Generate domain masks and attrs */ + cgroup_lock(); + ndoms = generate_sched_domains(&doms, &attr); + cgroup_unlock(); + + /* Have scheduler rebuild the domains */ + partition_sched_domains(ndoms, doms, attr); + + put_online_cpus(); +} + +static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains); + +/* + * Rebuild scheduler domains, asynchronously via workqueue. + * + * 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. + * + * The rebuild_sched_domains() and partition_sched_domains() + * routines must nest cgroup_lock() inside get_online_cpus(), + * but such cpuset changes as these must nest that locking the + * other way, holding cgroup_lock() for much of the code. + * + * So in order to avoid an ABBA deadlock, the cpuset code handling + * these user changes delegates the actual sched domain rebuilding + * to a separate workqueue thread, which ends up processing the + * above do_rebuild_sched_domains() function. + */ +static void async_rebuild_sched_domains(void) +{ + schedule_work(&rebuild_sched_domains_work); +} + +/* + * Accomplishes the same scheduler domain rebuild as the above + * async_rebuild_sched_domains(), however it directly calls the + * rebuild routine synchronously rather than calling it via an + * asynchronous work thread. + * + * This can only be called from code that is not holding + * cgroup_mutex (not nested in a cgroup_lock() call.) + */ +void rebuild_sched_domains(void) +{ + do_rebuild_sched_domains(NULL); +} + +/** + * cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's + * @tsk: task to test + * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner + * + * Call with cgroup_mutex held. May take callback_mutex during call. + * Called for each task in a cgroup by cgroup_scan_tasks(). + * Return nonzero if this tasks's cpus_allowed mask should be changed (in other + * words, if its mask is not equal to its cpuset's mask). + */ +static int cpuset_test_cpumask(struct task_struct *tsk, + struct cgroup_scanner *scan) +{ + return !cpus_equal(tsk->cpus_allowed, + (cgroup_cs(scan->cg))->cpus_allowed); +} + +/** + * cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's + * @tsk: task to test + * @scan: struct cgroup_scanner containing the cgroup of the task + * + * Called by cgroup_scan_tasks() for each task in a cgroup whose + * cpus_allowed mask needs to be changed. + * + * We don't need to re-check for the cgroup/cpuset membership, since we're + * holding cgroup_lock() at this point. + */ +static void cpuset_change_cpumask(struct task_struct *tsk, + struct cgroup_scanner *scan) +{ + set_cpus_allowed_ptr(tsk, &((cgroup_cs(scan->cg))->cpus_allowed)); +} + +/** + * 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 + * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks() + * + * Called with cgroup_mutex held + * + * The cgroup_scan_tasks() function will scan all the tasks in a cgroup, + * calling callback functions for each. + * + * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0 + * if @heap != NULL. + */ +static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap) +{ + struct cgroup_scanner scan; + + scan.cg = cs->css.cgroup; + scan.test_task = cpuset_test_cpumask; + scan.process_task = cpuset_change_cpumask; + scan.heap = heap; + cgroup_scan_tasks(&scan); +} + +/** + * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it + * @cs: the cpuset to consider + * @buf: buffer of cpu numbers written to this cpuset + */ +static int update_cpumask(struct cpuset *cs, const char *buf) +{ + struct ptr_heap heap; + struct cpuset trialcs; + int retval; + int is_load_balanced; + + /* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */ + if (cs == &top_cpuset) + return -EACCES; + + trialcs = *cs; + + /* + * 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) { + cpus_clear(trialcs.cpus_allowed); + } else { + retval = cpulist_parse(buf, trialcs.cpus_allowed); + if (retval < 0) + return retval; + + if (!cpus_subset(trialcs.cpus_allowed, cpu_online_map)) + return -EINVAL; + } + retval = validate_change(cs, &trialcs); + if (retval < 0) + return retval; + + /* Nothing to do if the cpus didn't change */ + if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed)) + return 0; + + retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL); + if (retval) + return retval; + + is_load_balanced = is_sched_load_balance(&trialcs); + + mutex_lock(&callback_mutex); + cs->cpus_allowed = trialcs.cpus_allowed; + mutex_unlock(&callback_mutex); + + /* + * Scan tasks in the cpuset, and update the cpumasks of any + * that need an update. + */ + update_tasks_cpumask(cs, &heap); + + heap_free(&heap); + + if (is_load_balanced) + async_rebuild_sched_domains(); + 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. + * + * Call holding cgroup_mutex, so current's cpuset won't change + * during this call, as manage_mutex holds off any cpuset_attach() + * calls. Therefore we don't need to take task_lock around the + * call to guarantee_online_mems(), as we know no one is changing + * our task's cpuset. + * + * Hold callback_mutex around the two modifications of our tasks + * mems_allowed to synchronize with cpuset_mems_allowed(). + * + * 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. + * + * We call cpuset_update_task_memory_state() before hacking + * our tasks mems_allowed, so that we are assured of being in + * sync with our tasks cpuset, and in particular, callbacks to + * cpuset_update_task_memory_state() from nested page allocations + * won't see any mismatch of our cpuset and task mems_generation + * values, so won't overwrite our hacked tasks mems_allowed + * nodemask. + */ + +static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, + const nodemask_t *to) +{ + struct task_struct *tsk = current; + + cpuset_update_task_memory_state(); + + mutex_lock(&callback_mutex); + tsk->mems_allowed = *to; + mutex_unlock(&callback_mutex); + + do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL); + + mutex_lock(&callback_mutex); + guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed); + mutex_unlock(&callback_mutex); +} + +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 + * @oldmem: old mems_allowed of cpuset cs + * + * Called with cgroup_mutex held + * Return 0 if successful, -errno if not. + */ +static int update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem) +{ + struct task_struct *p; + struct mm_struct **mmarray; + int i, n, ntasks; + int migrate; + int fudge; + struct cgroup_iter it; + int retval; + + cpuset_being_rebound = cs; /* causes mpol_dup() rebind */ + + fudge = 10; /* spare mmarray[] slots */ + fudge += cpus_weight(cs->cpus_allowed); /* imagine one fork-bomb/cpu */ + retval = -ENOMEM; + + /* + * Allocate mmarray[] to hold mm reference for each task + * in cpuset cs. Can't kmalloc GFP_KERNEL while holding + * tasklist_lock. We could use GFP_ATOMIC, but with a + * few more lines of code, we can retry until we get a big + * enough mmarray[] w/o using GFP_ATOMIC. + */ + while (1) { + ntasks = cgroup_task_count(cs->css.cgroup); /* guess */ + ntasks += fudge; + mmarray = kmalloc(ntasks * sizeof(*mmarray), GFP_KERNEL); + if (!mmarray) + goto done; + read_lock(&tasklist_lock); /* block fork */ + if (cgroup_task_count(cs->css.cgroup) <= ntasks) + break; /* got enough */ + read_unlock(&tasklist_lock); /* try again */ + kfree(mmarray); + } + + n = 0; + + /* Load up mmarray[] with mm reference for each task in cpuset. */ + cgroup_iter_start(cs->css.cgroup, &it); + while ((p = cgroup_iter_next(cs->css.cgroup, &it))) { + struct mm_struct *mm; + + if (n >= ntasks) { + printk(KERN_WARNING + "Cpuset mempolicy rebind incomplete.\n"); + break; + } + mm = get_task_mm(p); + if (!mm) + continue; + mmarray[n++] = mm; + } + cgroup_iter_end(cs->css.cgroup, &it); + read_unlock(&tasklist_lock); + + /* + * Now that we've dropped the tasklist spinlock, we can + * rebind the vma mempolicies of each mm in mmarray[] to their + * new cpuset, and release that mm. The mpol_rebind_mm() + * call takes mmap_sem, which we couldn't take while holding + * tasklist_lock. Forks can happen again now - the mpol_dup() + * cpuset_being_rebound check will catch such forks, and rebind + * their vma mempolicies too. Because we still hold the global + * cgroup_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. + */ + migrate = is_memory_migrate(cs); + for (i = 0; i < n; i++) { + struct mm_struct *mm = mmarray[i]; + + mpol_rebind_mm(mm, &cs->mems_allowed); + if (migrate) + cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed); + mmput(mm); + } + + /* We're done rebinding vmas to this cpuset's new mems_allowed. */ + kfree(mmarray); + cpuset_being_rebound = NULL; + retval = 0; +done: + return retval; +} + +/* + * Handle user request to change the 'mems' memory placement + * of a cpuset. Needs to validate the request, update the + * cpusets mems_allowed and mems_generation, and for each + * task in the cpuset, rebind any vma mempolicies and if + * the cpuset is marked 'memory_migrate', migrate the tasks + * pages to the new memory. + * + * Call with cgroup_mutex held. May take callback_mutex 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, const char *buf) +{ + struct cpuset trialcs; + nodemask_t oldmem; + int retval; + + /* + * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY]; + * it's read-only + */ + if (cs == &top_cpuset) + return -EACCES; + + trialcs = *cs; + + /* + * 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, + node_states[N_HIGH_MEMORY])) + return -EINVAL; + } + oldmem = cs->mems_allowed; + if (nodes_equal(oldmem, trialcs.mems_allowed)) { + retval = 0; /* Too easy - nothing to do */ + goto done; + } + retval = validate_change(cs, &trialcs); + if (retval < 0) + goto done; + + mutex_lock(&callback_mutex); + cs->mems_allowed = trialcs.mems_allowed; + cs->mems_generation = cpuset_mems_generation++; + mutex_unlock(&callback_mutex); + + retval = update_tasks_nodemask(cs, &oldmem); +done: + return retval; +} + +int current_cpuset_is_being_rebound(void) +{ + return task_cs(current) == cpuset_being_rebound; +} + +static int update_relax_domain_level(struct cpuset *cs, s64 val) +{ + if (val < -1 || val >= SD_LV_MAX) + return -EINVAL; + + if (val != cs->relax_domain_level) { + cs->relax_domain_level = val; + if (!cpus_empty(cs->cpus_allowed) && is_sched_load_balance(cs)) + async_rebuild_sched_domains(); + } + + return 0; +} + +/* + * 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 cgroup_mutex held. + */ + +static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, + int turning_on) +{ + struct cpuset trialcs; + int err; + int balance_flag_changed; + + trialcs = *cs; + if (turning_on) + set_bit(bit, &trialcs.flags); + else + clear_bit(bit, &trialcs.flags); + + err = validate_change(cs, &trialcs); + if (err < 0) + return err; + + balance_flag_changed = (is_sched_load_balance(cs) != + is_sched_load_balance(&trialcs)); + + mutex_lock(&callback_mutex); + cs->flags = trialcs.flags; + mutex_unlock(&callback_mutex); + + if (!cpus_empty(trialcs.cpus_allowed) && balance_flag_changed) + async_rebuild_sched_domains(); + + return 0; +} + +/* + * 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; +} + +/* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */ +static int cpuset_can_attach(struct cgroup_subsys *ss, + struct cgroup *cont, struct task_struct *tsk) +{ + struct cpuset *cs = cgroup_cs(cont); + + if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)) + return -ENOSPC; + if (tsk->flags & PF_THREAD_BOUND) { + cpumask_t mask; + + mutex_lock(&callback_mutex); + mask = cs->cpus_allowed; + mutex_unlock(&callback_mutex); + if (!cpus_equal(tsk->cpus_allowed, mask)) + return -EINVAL; + } + + return security_task_setscheduler(tsk, 0, NULL); +} + +static void cpuset_attach(struct cgroup_subsys *ss, + struct cgroup *cont, struct cgroup *oldcont, + struct task_struct *tsk) +{ + cpumask_t cpus; + nodemask_t from, to; + struct mm_struct *mm; + struct cpuset *cs = cgroup_cs(cont); + struct cpuset *oldcs = cgroup_cs(oldcont); + int err; + + mutex_lock(&callback_mutex); + guarantee_online_cpus(cs, &cpus); + err = set_cpus_allowed_ptr(tsk, &cpus); + mutex_unlock(&callback_mutex); + if (err) + return; + + from = oldcs->mems_allowed; + to = cs->mems_allowed; + mm = get_task_mm(tsk); + if (mm) { + mpol_rebind_mm(mm, &to); + if (is_memory_migrate(cs)) + cpuset_migrate_mm(mm, &from, &to); + mmput(mm); + } + +} + +/* The various types of files and directories in a cpuset file system */ + +typedef enum { + FILE_MEMORY_MIGRATE, + FILE_CPULIST, + FILE_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 *cgrp, struct cftype *cft, u64 val) +{ + int retval = 0; + struct cpuset *cs = cgroup_cs(cgrp); + cpuset_filetype_t type = cft->private; + + if (!cgroup_lock_live_group(cgrp)) + return -ENODEV; + + 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); + cs->mems_generation = cpuset_mems_generation++; + break; + case FILE_SPREAD_SLAB: + retval = update_flag(CS_SPREAD_SLAB, cs, val); + cs->mems_generation = cpuset_mems_generation++; + break; + default: + retval = -EINVAL; + break; + } + cgroup_unlock(); + return retval; +} + +static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val) +{ + int retval = 0; + struct cpuset *cs = cgroup_cs(cgrp); + cpuset_filetype_t type = cft->private; + + if (!cgroup_lock_live_group(cgrp)) + return -ENODEV; + + switch (type) { + case FILE_SCHED_RELAX_DOMAIN_LEVEL: + retval = update_relax_domain_level(cs, val); + break; + default: + retval = -EINVAL; + break; + } + cgroup_unlock(); + return retval; +} + +/* + * Common handling for a write to a "cpus" or "mems" file. + */ +static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft, + const char *buf) +{ + int retval = 0; + + if (!cgroup_lock_live_group(cgrp)) + return -ENODEV; + + switch (cft->private) { + case FILE_CPULIST: + retval = update_cpumask(cgroup_cs(cgrp), buf); + break; + case FILE_MEMLIST: + retval = update_nodemask(cgroup_cs(cgrp), buf); + break; + default: + retval = -EINVAL; + break; + } + cgroup_unlock(); + return retval; +} + +/* + * 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. + * A single large read to a buffer that crosses a page boundary is + * ok, because the result being copied to user land is not recomputed + * across a page fault. + */ + +static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs) +{ + cpumask_t mask; + + mutex_lock(&callback_mutex); + mask = cs->cpus_allowed; + mutex_unlock(&callback_mutex); + + return cpulist_scnprintf(page, PAGE_SIZE, mask); +} + +static int cpuset_sprintf_memlist(char *page, struct cpuset *cs) +{ + nodemask_t mask; + + mutex_lock(&callback_mutex); + mask = cs->mems_allowed; + mutex_unlock(&callback_mutex); + + return nodelist_scnprintf(page, PAGE_SIZE, mask); +} + +static ssize_t cpuset_common_file_read(struct cgroup *cont, + struct cftype *cft, + struct file *file, + char __user *buf, + size_t nbytes, loff_t *ppos) +{ + struct cpuset *cs = cgroup_cs(cont); + cpuset_filetype_t type = cft->private; + char *page; + ssize_t retval = 0; + char *s; + + if (!(page = (char *)__get_free_page(GFP_TEMPORARY))) + return -ENOMEM; + + s = page; + + switch (type) { + case FILE_CPULIST: + s += cpuset_sprintf_cpulist(s, cs); + break; + case FILE_MEMLIST: + s += cpuset_sprintf_memlist(s, cs); + break; + default: + retval = -EINVAL; + goto out; + } + *s++ = '\n'; + + retval = simple_read_from_buffer(buf, nbytes, ppos, page, s - page); +out: + free_page((unsigned long)page); + return retval; +} + +static u64 cpuset_read_u64(struct cgroup *cont, struct cftype *cft) +{ + struct cpuset *cs = cgroup_cs(cont); + 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 *cont, struct cftype *cft) +{ + struct cpuset *cs = cgroup_cs(cont); + 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", + .read = cpuset_common_file_read, + .write_string = cpuset_write_resmask, + .max_write_len = (100U + 6 * NR_CPUS), + .private = FILE_CPULIST, + }, + + { + .name = "mems", + .read = cpuset_common_file_read, + .write_string = cpuset_write_resmask, + .max_write_len = (100U + 6 * MAX_NUMNODES), + .private = FILE_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, + }, + + { + .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, + }, +}; + +static struct cftype cft_memory_pressure_enabled = { + .name = "memory_pressure_enabled", + .read_u64 = cpuset_read_u64, + .write_u64 = cpuset_write_u64, + .private = FILE_MEMORY_PRESSURE_ENABLED, +}; + +static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont) +{ + int err; + + err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files)); + if (err) + return err; + /* memory_pressure_enabled is in root cpuset only */ + if (!cont->parent) + err = cgroup_add_file(cont, ss, + &cft_memory_pressure_enabled); + return err; +} + +/* + * post_clone() is called at the end of cgroup_clone(). + * 'cgroup' was just created automatically as a result of + * a cgroup_clone(), and the current task is about to + * be moved into 'cgroup'. + * + * Currently we refuse to set up the cgroup - thereby + * refusing the task to be entered, and as a result refusing + * the sys_unshare() or clone() which initiated it - if any + * sibling cpusets have exclusive cpus or mem. + * + * If this becomes a problem for some users who wish to + * allow that scenario, then cpuset_post_clone() could be + * changed to grant parent->cpus_allowed-sibling_cpus_exclusive + * (and likewise for mems) to the new cgroup. Called with cgroup_mutex + * held. + */ +static void cpuset_post_clone(struct cgroup_subsys *ss, + struct cgroup *cgroup) +{ + struct cgroup *parent, *child; + struct cpuset *cs, *parent_cs; + + parent = cgroup->parent; + list_for_each_entry(child, &parent->children, sibling) { + cs = cgroup_cs(child); + if (is_mem_exclusive(cs) || is_cpu_exclusive(cs)) + return; + } + cs = cgroup_cs(cgroup); + parent_cs = cgroup_cs(parent); + + cs->mems_allowed = parent_cs->mems_allowed; + cs->cpus_allowed = parent_cs->cpus_allowed; + return; +} + +/* + * cpuset_create - create a cpuset + * ss: cpuset cgroup subsystem + * cont: control group that the new cpuset will be part of + */ + +static struct cgroup_subsys_state *cpuset_create( + struct cgroup_subsys *ss, + struct cgroup *cont) +{ + struct cpuset *cs; + struct cpuset *parent; + + if (!cont->parent) { + /* This is early initialization for the top cgroup */ + top_cpuset.mems_generation = cpuset_mems_generation++; + return &top_cpuset.css; + } + parent = cgroup_cs(cont->parent); + cs = kmalloc(sizeof(*cs), GFP_KERNEL); + if (!cs) + return ERR_PTR(-ENOMEM); + + cpuset_update_task_memory_state(); + cs->flags = 0; + if (is_spread_page(parent)) + set_bit(CS_SPREAD_PAGE, &cs->flags); + if (is_spread_slab(parent)) + set_bit(CS_SPREAD_SLAB, &cs->flags); + set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags); + cpus_clear(cs->cpus_allowed); + nodes_clear(cs->mems_allowed); + cs->mems_generation = cpuset_mems_generation++; + fmeter_init(&cs->fmeter); + cs->relax_domain_level = -1; + + cs->parent = parent; + number_of_cpusets++; + return &cs->css ; +} + +/* + * If the cpuset being removed has its flag 'sched_load_balance' + * enabled, then simulate turning sched_load_balance off, which + * will call async_rebuild_sched_domains(). + */ + +static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont) +{ + struct cpuset *cs = cgroup_cs(cont); + + cpuset_update_task_memory_state(); + + if (is_sched_load_balance(cs)) + update_flag(CS_SCHED_LOAD_BALANCE, cs, 0); + + number_of_cpusets--; + kfree(cs); +} + +struct cgroup_subsys cpuset_subsys = { + .name = "cpuset", + .create = cpuset_create, + .destroy = cpuset_destroy, + .can_attach = cpuset_can_attach, + .attach = cpuset_attach, + .populate = cpuset_populate, + .post_clone = cpuset_post_clone, + .subsys_id = cpuset_subsys_id, + .early_init = 1, +}; + +/* + * cpuset_init_early - just enough so that the calls to + * cpuset_update_task_memory_state() in early init code + * are harmless. + */ + +int __init cpuset_init_early(void) +{ + top_cpuset.mems_generation = cpuset_mems_generation++; + return 0; +} + + +/** + * 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; + + cpus_setall(top_cpuset.cpus_allowed); + nodes_setall(top_cpuset.mems_allowed); + + fmeter_init(&top_cpuset.fmeter); + top_cpuset.mems_generation = cpuset_mems_generation++; + 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; + + number_of_cpusets = 1; + return 0; +} + +/** + * cpuset_do_move_task - move a given task to another cpuset + * @tsk: pointer to task_struct the task to move + * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner + * + * Called by cgroup_scan_tasks() for each task in a cgroup. + * Return nonzero to stop the walk through the tasks. + */ +static void cpuset_do_move_task(struct task_struct *tsk, + struct cgroup_scanner *scan) +{ + struct cpuset_hotplug_scanner *chsp; + + chsp = container_of(scan, struct cpuset_hotplug_scanner, scan); + cgroup_attach_task(chsp->to, tsk); +} + +/** + * move_member_tasks_to_cpuset - move tasks from one cpuset to another + * @from: cpuset in which the tasks currently reside + * @to: cpuset to which the tasks will be moved + * + * Called with cgroup_mutex held + * callback_mutex must not be held, as cpuset_attach() will take it. + * + * The cgroup_scan_tasks() function will scan all the tasks in a cgroup, + * calling callback functions for each. + */ +static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to) +{ + struct cpuset_hotplug_scanner scan; + + scan.scan.cg = from->css.cgroup; + scan.scan.test_task = NULL; /* select all tasks in cgroup */ + scan.scan.process_task = cpuset_do_move_task; + scan.scan.heap = NULL; + scan.to = to->css.cgroup; + + if (cgroup_scan_tasks(&scan.scan)) + printk(KERN_ERR "move_member_tasks_to_cpuset: " + "cgroup_scan_tasks failed\n"); +} + +/* + * 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. + * + * Called with cgroup_mutex held + * callback_mutex must not be held, as cpuset_attach() will take it. + */ +static void remove_tasks_in_empty_cpuset(struct cpuset *cs) +{ + struct cpuset *parent; + + /* + * The cgroup's css_sets list is in use if there are tasks + * in the cpuset; the list is empty if there are none; + * the cs->css.refcnt seems always 0. + */ + if (list_empty(&cs->css.cgroup->css_sets)) + return; + + /* + * Find its next-highest non-empty parent, (top cpuset + * has online cpus, so can't be empty). + */ + parent = cs->parent; + while (cpus_empty(parent->cpus_allowed) || + nodes_empty(parent->mems_allowed)) + parent = parent->parent; + + move_member_tasks_to_cpuset(cs, parent); +} + +/* + * Walk the specified cpuset subtree and look for empty cpusets. + * The tasks of such cpuset must be moved to a parent cpuset. + * + * Called with cgroup_mutex held. We take callback_mutex to modify + * cpus_allowed and mems_allowed. + * + * This walk processes the tree from top to bottom, completing one layer + * before dropping down to the next. It always processes a node before + * any of its children. + * + * For now, since we lack memory hot unplug, we'll never see a cpuset + * that has tasks along with an empty 'mems'. But if we did see such + * a cpuset, we'd handle it just like we do if its 'cpus' was empty. + */ +static void scan_for_empty_cpusets(struct cpuset *root) +{ + LIST_HEAD(queue); + struct cpuset *cp; /* scans cpusets being updated */ + struct cpuset *child; /* scans child cpusets of cp */ + struct cgroup *cont; + nodemask_t oldmems; + + list_add_tail((struct list_head *)&root->stack_list, &queue); + + while (!list_empty(&queue)) { + cp = list_first_entry(&queue, struct cpuset, stack_list); + list_del(queue.next); + list_for_each_entry(cont, &cp->css.cgroup->children, sibling) { + child = cgroup_cs(cont); + list_add_tail(&child->stack_list, &queue); + } + + /* Continue past cpusets with all cpus, mems online */ + if (cpus_subset(cp->cpus_allowed, cpu_online_map) && + nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY])) + continue; + + oldmems = cp->mems_allowed; + + /* Remove offline cpus and mems from this cpuset. */ + mutex_lock(&callback_mutex); + cpus_and(cp->cpus_allowed, cp->cpus_allowed, cpu_online_map); + nodes_and(cp->mems_allowed, cp->mems_allowed, + node_states[N_HIGH_MEMORY]); + mutex_unlock(&callback_mutex); + + /* Move tasks from the empty cpuset to a parent */ + if (cpus_empty(cp->cpus_allowed) || + nodes_empty(cp->mems_allowed)) + remove_tasks_in_empty_cpuset(cp); + else { + update_tasks_cpumask(cp, NULL); + update_tasks_nodemask(cp, &oldmems); + } + } +} + +/* + * The top_cpuset tracks what CPUs and Memory Nodes are online, + * period. This 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. + * + * This routine ensures that top_cpuset.cpus_allowed tracks + * cpu_online_map on each CPU hotplug (cpuhp) event. + * + * Called within get_online_cpus(). Needs to call cgroup_lock() + * before calling generate_sched_domains(). + */ +static int cpuset_track_online_cpus(struct notifier_block *unused_nb, + unsigned long phase, void *unused_cpu) +{ + struct sched_domain_attr *attr; + cpumask_t *doms; + int ndoms; + + switch (phase) { + case CPU_ONLINE: + case CPU_ONLINE_FROZEN: + case CPU_DEAD: + case CPU_DEAD_FROZEN: + break; + + default: + return NOTIFY_DONE; + } + + cgroup_lock(); + top_cpuset.cpus_allowed = cpu_online_map; + scan_for_empty_cpusets(&top_cpuset); + ndoms = generate_sched_domains(&doms, &attr); + cgroup_unlock(); + + /* Have scheduler rebuild the domains */ + partition_sched_domains(ndoms, doms, attr); + + return NOTIFY_OK; +} + +#ifdef CONFIG_MEMORY_HOTPLUG +/* + * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY]. + * Call this routine anytime after node_states[N_HIGH_MEMORY] changes. + * See also the previous routine cpuset_track_online_cpus(). + */ +static int cpuset_track_online_nodes(struct notifier_block *self, + unsigned long action, void *arg) +{ + cgroup_lock(); + switch (action) { + case MEM_ONLINE: + top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; + break; + case MEM_OFFLINE: + top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; + scan_for_empty_cpusets(&top_cpuset); + break; + default: + break; + } + cgroup_unlock(); + return NOTIFY_OK; +} +#endif + +/** + * cpuset_init_smp - initialize cpus_allowed + * + * Description: Finish top cpuset after cpu, node maps are initialized + **/ + +void __init cpuset_init_smp(void) +{ + top_cpuset.cpus_allowed = cpu_online_map; + top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; + + hotcpu_notifier(cpuset_track_online_cpus, 0); + hotplug_memory_notifier(cpuset_track_online_nodes, 10); +} + +/** + * 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 cpumask_t variable to receive cpus_allowed set. + * + * Description: Returns the cpumask_t cpus_allowed of the cpuset + * attached to the specified @tsk. Guaranteed to return some non-empty + * subset of cpu_online_map, even if this means going outside the + * tasks cpuset. + **/ + +void cpuset_cpus_allowed(struct task_struct *tsk, cpumask_t *pmask) +{ + mutex_lock(&callback_mutex); + cpuset_cpus_allowed_locked(tsk, pmask); + mutex_unlock(&callback_mutex); +} + +/** + * cpuset_cpus_allowed_locked - return cpus_allowed mask from a tasks cpuset. + * Must be called with callback_mutex held. + **/ +void cpuset_cpus_allowed_locked(struct task_struct *tsk, cpumask_t *pmask) +{ + task_lock(tsk); + guarantee_online_cpus(task_cs(tsk), pmask); + task_unlock(tsk); +} + +void 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_HIGH_MEMORY], even if this means going outside the + * tasks cpuset. + **/ + +nodemask_t cpuset_mems_allowed(struct task_struct *tsk) +{ + nodemask_t mask; + + mutex_lock(&callback_mutex); + task_lock(tsk); + guarantee_online_mems(task_cs(tsk), &mask); + task_unlock(tsk); + mutex_unlock(&callback_mutex); + + 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_mutex. If no ancestor is mem_exclusive or mem_hardwall + * (an unusual configuration), then returns the root cpuset. + */ +static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs) +{ + while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && cs->parent) + cs = cs->parent; + return cs; +} + +/** + * cpuset_zone_allowed_softwall - Can we allocate on zone z's memory node? + * @z: is this zone on an allowed node? + * @gfp_mask: memory allocation flags + * + * If we're in interrupt, yes, we can always allocate. If + * __GFP_THISNODE is set, yes, we can always allocate. If zone + * z's node is in our tasks mems_allowed, yes. If it's not a + * __GFP_HARDWALL request and this zone's nodes is in the nearest + * hardwalled cpuset ancestor to this tasks cpuset, yes. + * If the task has been OOM killed and has access to memory reserves + * as specified by the TIF_MEMDIE flag, yes. + * Otherwise, no. + * + * If __GFP_HARDWALL is set, cpuset_zone_allowed_softwall() + * reduces to cpuset_zone_allowed_hardwall(). Otherwise, + * cpuset_zone_allowed_softwall() might sleep, and might allow a zone + * from an enclosing cpuset. + * + * cpuset_zone_allowed_hardwall() only handles the simpler case of + * hardwall cpusets, and never sleeps. + * + * The __GFP_THISNODE placement logic is really handled elsewhere, + * by forcibly using a zonelist starting at a specified node, and by + * (in get_page_from_freelist()) refusing to consider the zones for + * any node on the zonelist except the first. By the time any such + * calls get to this routine, we should just shut up and say 'yes'. + * + * 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_mutex. 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_mutex + * mutex. + * + * 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. + * + * Rule: + * Don't call cpuset_zone_allowed_softwall if you can't sleep, unless you + * pass in the __GFP_HARDWALL flag set in gfp_flag, which disables + * the code that might scan up ancestor cpusets and sleep. + */ + +int __cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask) +{ + int node; /* node that zone z is on */ + const struct cpuset *cs; /* current cpuset ancestors */ + int allowed; /* is allocation in zone z allowed? */ + + if (in_interrupt() || (gfp_mask & __GFP_THISNODE)) + return 1; + node = zone_to_nid(z); + might_sleep_if(!(gfp_mask & __GFP_HARDWALL)); + 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 */ + mutex_lock(&callback_mutex); + + task_lock(current); + cs = nearest_hardwall_ancestor(task_cs(current)); + task_unlock(current); + + allowed = node_isset(node, cs->mems_allowed); + mutex_unlock(&callback_mutex); + return allowed; +} + +/* + * cpuset_zone_allowed_hardwall - Can we allocate on zone z's memory node? + * @z: is this zone on an allowed node? + * @gfp_mask: memory allocation flags + * + * If we're in interrupt, yes, we can always allocate. + * If __GFP_THISNODE is set, yes, we can always allocate. If zone + * z's node is in our tasks mems_allowed, yes. If the task has been + * OOM killed and has access to memory reserves as specified by the + * TIF_MEMDIE flag, yes. Otherwise, no. + * + * The __GFP_THISNODE placement logic is really handled elsewhere, + * by forcibly using a zonelist starting at a specified node, and by + * (in get_page_from_freelist()) refusing to consider the zones for + * any node on the zonelist except the first. By the time any such + * calls get to this routine, we should just shut up and say 'yes'. + * + * Unlike the cpuset_zone_allowed_softwall() variant, above, + * this variant requires that the zone be in the current tasks + * mems_allowed or that we're in interrupt. It does not scan up the + * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset. + * It never sleeps. + */ + +int __cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask) +{ + int node; /* node that zone z is on */ + + if (in_interrupt() || (gfp_mask & __GFP_THISNODE)) + return 1; + node = zone_to_nid(z); + 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; + return 0; +} + +/** + * cpuset_lock - lock out any changes to cpuset structures + * + * The out of memory (oom) code needs to mutex_lock cpusets + * from being changed while it scans the tasklist looking for a + * task in an overlapping cpuset. Expose callback_mutex via this + * cpuset_lock() routine, so the oom code can lock it, before + * locking the task list. The tasklist_lock is a spinlock, so + * must be taken inside callback_mutex. + */ + +void cpuset_lock(void) +{ + mutex_lock(&callback_mutex); +} + +/** + * cpuset_unlock - release lock on cpuset changes + * + * Undo the lock taken in a previous cpuset_lock() call. + */ + +void cpuset_unlock(void) +{ + mutex_unlock(&callback_mutex); +} + +/** + * cpuset_mem_spread_node() - On which node to begin search for a 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(). + */ + +int cpuset_mem_spread_node(void) +{ + int node; + + node = next_node(current->cpuset_mem_spread_rotor, current->mems_allowed); + if (node == MAX_NUMNODES) + node = first_node(current->mems_allowed); + current->cpuset_mem_spread_rotor = node; + return node; +} +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); +} + +/* + * 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) +{ + task_lock(current); + fmeter_markevent(&task_cs(current)->fmeter); + task_unlock(current); +} + +#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 cgroup_mutex, keeping cpuset_attach() from changing it + * anyway. + */ +static int proc_cpuset_show(struct seq_file *m, void *unused_v) +{ + struct pid *pid; + struct task_struct *tsk; + char *buf; + struct cgroup_subsys_state *css; + int retval; + + retval = -ENOMEM; + buf = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!buf) + goto out; + + retval = -ESRCH; + pid = m->private; + tsk = get_pid_task(pid, PIDTYPE_PID); + if (!tsk) + goto out_free; + + retval = -EINVAL; + cgroup_lock(); + css = task_subsys_state(tsk, cpuset_subsys_id); + retval = cgroup_path(css->cgroup, buf, PAGE_SIZE); + if (retval < 0) + goto out_unlock; + seq_puts(m, buf); + seq_putc(m, '\n'); +out_unlock: + cgroup_unlock(); + put_task_struct(tsk); +out_free: + kfree(buf); +out: + return retval; +} + +static int cpuset_open(struct inode *inode, struct file *file) +{ + struct pid *pid = PROC_I(inode)->pid; + return single_open(file, proc_cpuset_show, pid); +} + +const struct file_operations proc_cpuset_operations = { + .open = cpuset_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; +#endif /* CONFIG_PROC_PID_CPUSET */ + +/* Display task cpus_allowed, mems_allowed in /proc/<pid>/status file. */ +void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task) +{ + seq_printf(m, "Cpus_allowed:\t"); + seq_cpumask(m, &task->cpus_allowed); + seq_printf(m, "\n"); + seq_printf(m, "Cpus_allowed_list:\t"); + seq_cpumask_list(m, &task->cpus_allowed); + seq_printf(m, "\n"); + seq_printf(m, "Mems_allowed:\t"); + seq_nodemask(m, &task->mems_allowed); + seq_printf(m, "\n"); + seq_printf(m, "Mems_allowed_list:\t"); + seq_nodemask_list(m, &task->mems_allowed); + seq_printf(m, "\n"); +} |
