/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Workqueue for cpuset related tasks. * * Using kevent workqueue may cause deadlock when memory_migrate * is set. So we create a separate workqueue thread for cpuset. */ static struct workqueue_struct *cpuset_wq; /* * 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_var_t cpus_allowed; /* CPUs allowed to tasks in cpuset */ nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */ struct cpuset *parent; /* my parent */ 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 hierarchy */ 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); } #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_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE, CS_MEM_HARDWALL, CS_MEMORY_MIGRATE, CS_SCHED_LOAD_BALANCE, CS_SPREAD_PAGE, CS_SPREAD_SLAB, } cpuset_flagbits_t; /* the type of hotplug event */ enum hotplug_event { CPUSET_CPU_OFFLINE, CPUSET_MEM_OFFLINE, }; /* 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); } static struct cpuset top_cpuset = { .flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)), }; /* * 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. * * 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_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); /* * cpuset_buffer_lock protects both the cpuset_name and cpuset_nodelist * buffers. They are statically allocated to prevent using excess stack * when calling cpuset_print_task_mems_allowed(). */ #define CPUSET_NAME_LEN (128) #define CPUSET_NODELIST_LEN (256) static char cpuset_name[CPUSET_NAME_LEN]; static char cpuset_nodelist[CPUSET_NODELIST_LEN]; static DEFINE_SPINLOCK(cpuset_buffer_lock); /* * 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. If we get * all the way to the top and still haven't found any online cpus, * return cpu_online_mask. Or if passed a NULL cs from an exit'ing * task, return cpu_online_mask. * * One way or another, we guarantee to return some non-empty subset * of cpu_online_mask. * * Call with callback_mutex held. */ static void guarantee_online_cpus(const struct cpuset *cs, struct cpumask *pmask) { while (cs && !cpumask_intersects(cs->cpus_allowed, cpu_online_mask)) cs = cs->parent; if (cs) cpumask_and(pmask, cs->cpus_allowed, cpu_online_mask); else cpumask_copy(pmask, cpu_online_mask); BUG_ON(!cpumask_intersects(pmask, 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. 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])); } /* * update task's spread flag if cpuset's page/slab spread flag is set * * Called with callback_mutex/cgroup_mutex held */ static void cpuset_update_task_spread_flag(struct cpuset *cs, struct task_struct *tsk) { 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; } /* * 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 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(const 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)) { kfree(trial); return NULL; } cpumask_copy(trial->cpus_allowed, cs->cpus_allowed); return trial; } /** * 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->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 * 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 && cpumask_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 (cpumask_empty(trial->cpus_allowed) || nodes_empty(trial->mems_allowed)) { return -ENOSPC; } } return 0; } #ifdef CONFIG_SMP /* * 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 cpumask_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 (cpumask_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/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 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_var_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_var_t *doms; /* resulting partition; i.e. sched domains */ struct sched_domain_attr *dattr; /* attributes for custom domains */ int ndoms = 0; /* number of sched domains in result */ int nslot; /* next empty doms[] struct cpumask slot */ 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)) { 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_copy(doms[0], top_cpuset.cpus_allowed); 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 (cpumask_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 to 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) { 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; } 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->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_var_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(); } #else /* !CONFIG_SMP */ static void do_rebuild_sched_domains(struct work_struct *unused) { } static int generate_sched_domains(cpumask_var_t **domains, struct sched_domain_attr **attributes) { *domains = NULL; return 1; } #endif /* CONFIG_SMP */ 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) { queue_work(cpuset_wq, &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 !cpumask_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, struct cpuset *trialcs, const char *buf) { struct ptr_heap heap; int retval; int is_load_balanced; /* 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, cpu_active_mask)) return -EINVAL; } retval = validate_change(cs, trialcs); if (retval < 0) return retval; /* Nothing to do if the cpus didn't change */ if (cpumask_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); cpumask_copy(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. * * 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); guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed); } /* * 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 * get_mems_allowed(). 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) 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); task_unlock(tsk); } /* * Update task's mems_allowed and rebind its mempolicy and vmas' mempolicy * of it to cpuset's new mems_allowed, and migrate pages to new nodes if * memory_migrate flag is set. Called with cgroup_mutex held. */ static void cpuset_change_nodemask(struct task_struct *p, struct cgroup_scanner *scan) { struct mm_struct *mm; struct cpuset *cs; int migrate; const nodemask_t *oldmem = scan->data; static nodemask_t newmems; /* protected by cgroup_mutex */ cs = cgroup_cs(scan->cg); guarantee_online_mems(cs, &newmems); cpuset_change_task_nodemask(p, &newmems); mm = get_task_mm(p); if (!mm) return; migrate = is_memory_migrate(cs); mpol_rebind_mm(mm, &cs->mems_allowed); if (migrate) cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed); mmput(mm); } 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 * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks() * * Called with cgroup_mutex held * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0 * if @heap != NULL. */ static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem, struct ptr_heap *heap) { struct cgroup_scanner scan; cpuset_being_rebound = cs; /* causes mpol_dup() rebind */ scan.cg = cs->css.cgroup; scan.test_task = NULL; scan.process_task = cpuset_change_nodemask; scan.heap = heap; scan.data = (nodemask_t *)oldmem; /* * 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 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. */ cgroup_scan_tasks(&scan); /* We're done rebinding vmas to this cpuset's new mems_allowed. */ cpuset_being_rebound = NULL; } /* * 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 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, struct cpuset *trialcs, const char *buf) { NODEMASK_ALLOC(nodemask_t, oldmem, GFP_KERNEL); int retval; struct ptr_heap heap; if (!oldmem) return -ENOMEM; /* * top_cpuset.mems_allowed tracks node_stats[N_HIGH_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, node_states[N_HIGH_MEMORY])) { retval = -EINVAL; goto done; } } *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; retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL); if (retval < 0) goto done; mutex_lock(&callback_mutex); cs->mems_allowed = trialcs->mems_allowed; mutex_unlock(&callback_mutex); update_tasks_nodemask(cs, oldmem, &heap); heap_free(&heap); done: NODEMASK_FREE(oldmem); 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) { #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)) async_rebuild_sched_domains(); } return 0; } /* * cpuset_change_flag - make a task's spread flags the same as its cpuset's * @tsk: task to be updated * @scan: struct cgroup_scanner containing the cgroup of the task * * Called by cgroup_scan_tasks() for each task in a cgroup. * * 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_flag(struct task_struct *tsk, struct cgroup_scanner *scan) { cpuset_update_task_spread_flag(cgroup_cs(scan->cg), tsk); } /* * 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 * @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_flags(struct cpuset *cs, struct ptr_heap *heap) { struct cgroup_scanner scan; scan.cg = cs->css.cgroup; scan.test_task = NULL; scan.process_task = cpuset_change_flag; scan.heap = heap; cgroup_scan_tasks(&scan); } /* * 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 balance_flag_changed; int spread_flag_changed; struct ptr_heap heap; 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; err = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL); 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))); mutex_lock(&callback_mutex); cs->flags = trialcs->flags; mutex_unlock(&callback_mutex); if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed) async_rebuild_sched_domains(); if (spread_flag_changed) update_tasks_flags(cs, &heap); heap_free(&heap); 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; } /* * Protected by cgroup_lock. The nodemasks must be stored globally because * dynamically allocating them is not allowed in can_attach, and they must * persist until attach. */ static cpumask_var_t cpus_attach; static nodemask_t cpuset_attach_nodemask_from; static nodemask_t cpuset_attach_nodemask_to; /* Called by cgroups to determine if a cpuset is usable; cgroup_mutex held */ static int cpuset_can_attach(struct cgroup *cgrp, struct cgroup_taskset *tset) { struct cpuset *cs = cgroup_cs(cgrp); struct task_struct *task; int ret; if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)) return -ENOSPC; cgroup_taskset_for_each(task, cgrp, tset) { /* * Kthreads bound to specific cpus cannot be moved to a new * cpuset; we cannot change their cpu affinity and * isolating such threads by their set of allowed nodes is * unnecessary. Thus, cpusets are not applicable for such * threads. This prevents checking for success of * set_cpus_allowed_ptr() on all attached tasks before * cpus_allowed may be changed. */ if (task->flags & PF_THREAD_BOUND) return -EINVAL; if ((ret = security_task_setscheduler(task))) return ret; } /* 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); return 0; } static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset) { struct mm_struct *mm; struct task_struct *task; struct task_struct *leader = cgroup_taskset_first(tset); struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset); struct cpuset *cs = cgroup_cs(cgrp); struct cpuset *oldcs = cgroup_cs(oldcgrp); cgroup_taskset_for_each(task, cgrp, 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_from = oldcs->mems_allowed; cpuset_attach_nodemask_to = cs->mems_allowed; mm = get_task_mm(leader); if (mm) { mpol_rebind_mm(mm, &cpuset_attach_nodemask_to); if (is_memory_migrate(cs)) cpuset_migrate_mm(mm, &cpuset_attach_nodemask_from, &cpuset_attach_nodemask_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); break; case FILE_SPREAD_SLAB: retval = update_flag(CS_SPREAD_SLAB, cs, val); 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; struct cpuset *cs = cgroup_cs(cgrp); struct cpuset *trialcs; if (!cgroup_lock_live_group(cgrp)) return -ENODEV; trialcs = alloc_trial_cpuset(cs); if (!trialcs) { retval = -ENOMEM; goto out; } switch (cft->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: 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 size_t cpuset_sprintf_cpulist(char *page, struct cpuset *cs) { size_t count; mutex_lock(&callback_mutex); count = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed); mutex_unlock(&callback_mutex); return count; } static size_t cpuset_sprintf_memlist(char *page, struct cpuset *cs) { size_t count; mutex_lock(&callback_mutex); count = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed); mutex_unlock(&callback_mutex); return count; } 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, .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 */ }; /* * post_clone() is called during cgroup_create() when the * clone_children mount argument was specified. The cgroup * can not yet have any tasks. * * 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 *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); mutex_lock(&callback_mutex); cs->mems_allowed = parent_cs->mems_allowed; cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed); mutex_unlock(&callback_mutex); return; } /* * cpuset_create - create a cpuset * cont: control group that the new cpuset will be part of */ static struct cgroup_subsys_state *cpuset_create(struct cgroup *cont) { struct cpuset *cs; struct cpuset *parent; if (!cont->parent) { return &top_cpuset.css; } parent = cgroup_cs(cont->parent); cs = kmalloc(sizeof(*cs), GFP_KERNEL); if (!cs) return ERR_PTR(-ENOMEM); if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) { kfree(cs); return ERR_PTR(-ENOMEM); } 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); cpumask_clear(cs->cpus_allowed); nodes_clear(cs->mems_allowed); 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 *cont) { struct cpuset *cs = cgroup_cs(cont); if (is_sched_load_balance(cs)) update_flag(CS_SCHED_LOAD_BALANCE, cs, 0); number_of_cpusets--; free_cpumask_var(cs->cpus_allowed); kfree(cs); } struct cgroup_subsys cpuset_subsys = { .name = "cpuset", .create = cpuset_create, .destroy = cpuset_destroy, .can_attach = cpuset_can_attach, .attach = cpuset_attach, .post_clone = cpuset_post_clone, .subsys_id = cpuset_subsys_id, .base_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(); cpumask_setall(top_cpuset.cpus_allowed); nodes_setall(top_cpuset.mems_allowed); 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(); 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 cgroup *new_cgroup = scan->data; cgroup_attach_task(new_cgroup, 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 cgroup_scanner scan; scan.cg = from->css.cgroup; scan.test_task = NULL; /* select all tasks in cgroup */ scan.process_task = cpuset_do_move_task; scan.heap = NULL; scan.data = to->css.cgroup; if (cgroup_scan_tasks(&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 (cpumask_empty(parent->cpus_allowed) || nodes_empty(parent->mems_allowed)) parent = parent->parent; move_member_tasks_to_cpuset(cs, parent); } /* * Helper function to traverse cpusets. * It can be used to walk the cpuset tree from top to bottom, completing * one layer before dropping down to the next (thus always processing a * node before any of its children). */ static struct cpuset *cpuset_next(struct list_head *queue) { struct cpuset *cp; struct cpuset *child; /* scans child cpusets of cp */ struct cgroup *cont; if (list_empty(queue)) return NULL; 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); } return cp; } /* * Walk the specified cpuset subtree upon a hotplug operation (CPU/Memory * online/offline) and update the cpusets accordingly. * For regular CPU/Mem hotplug, 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_cpusets_upon_hotplug(struct cpuset *root, enum hotplug_event event) { LIST_HEAD(queue); struct cpuset *cp; /* scans cpusets being updated */ static nodemask_t oldmems; /* protected by cgroup_mutex */ list_add_tail((struct list_head *)&root->stack_list, &queue); switch (event) { case CPUSET_CPU_OFFLINE: while ((cp = cpuset_next(&queue)) != NULL) { /* Continue past cpusets with all cpus online */ if (cpumask_subset(cp->cpus_allowed, cpu_active_mask)) continue; /* Remove offline cpus from this cpuset. */ mutex_lock(&callback_mutex); cpumask_and(cp->cpus_allowed, cp->cpus_allowed, cpu_active_mask); mutex_unlock(&callback_mutex); /* Move tasks from the empty cpuset to a parent */ if (cpumask_empty(cp->cpus_allowed)) remove_tasks_in_empty_cpuset(cp); else update_tasks_cpumask(cp, NULL); } break; case CPUSET_MEM_OFFLINE: while ((cp = cpuset_next(&queue)) != NULL) { /* Continue past cpusets with all mems online */ if (nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY])) continue; oldmems = cp->mems_allowed; /* Remove offline mems from this cpuset. */ mutex_lock(&callback_mutex); 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 (nodes_empty(cp->mems_allowed)) remove_tasks_in_empty_cpuset(cp); else update_tasks_nodemask(cp, &oldmems, NULL); } } } /* * 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. * * The only exception to this is suspend/resume, where we don't * modify cpusets at all. * * This routine ensures that top_cpuset.cpus_allowed tracks * cpu_active_mask on each CPU hotplug (cpuhp) event. * * Called within get_online_cpus(). Needs to call cgroup_lock() * before calling generate_sched_domains(). * * @cpu_online: Indicates whether this is a CPU online event (true) or * a CPU offline event (false). */ void cpuset_update_active_cpus(bool cpu_online) { struct sched_domain_attr *attr; cpumask_var_t *doms; int ndoms; cgroup_lock(); mutex_lock(&callback_mutex); cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask); mutex_unlock(&callback_mutex); if (!cpu_online) scan_cpusets_upon_hotplug(&top_cpuset, CPUSET_CPU_OFFLINE); ndoms = generate_sched_domains(&doms, &attr); cgroup_unlock(); /* Have scheduler rebuild the domains */ partition_sched_domains(ndoms, doms, attr); } #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) { static nodemask_t oldmems; /* protected by cgroup_mutex */ cgroup_lock(); switch (action) { case MEM_ONLINE: oldmems = top_cpuset.mems_allowed; mutex_lock(&callback_mutex); top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; mutex_unlock(&callback_mutex); update_tasks_nodemask(&top_cpuset, &oldmems, NULL); break; case MEM_OFFLINE: /* * needn't update top_cpuset.mems_allowed explicitly because * scan_cpusets_upon_hotplug() will update it. */ scan_cpusets_upon_hotplug(&top_cpuset, CPUSET_MEM_OFFLINE); 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) { cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask); top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; hotplug_memory_notifier(cpuset_track_online_nodes, 10); cpuset_wq = create_singlethread_workqueue("cpuset"); BUG_ON(!cpuset_wq); } /** * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset. * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed. * @pmask: pointer to struct cpumask variable to receive cpus_allowed set. * * Description: Returns the cpumask_var_t cpus_allowed of the cpuset * attached to the specified @tsk. Guaranteed to return some non-empty * subset of cpu_online_mask, even if this means going outside the * tasks cpuset. **/ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) { mutex_lock(&callback_mutex); task_lock(tsk); guarantee_online_cpus(task_cs(tsk), pmask); task_unlock(tsk); mutex_unlock(&callback_mutex); } void cpuset_cpus_allowed_fallback(struct task_struct *tsk) { const struct cpuset *cs; rcu_read_lock(); cs = task_cs(tsk); if (cs) do_set_cpus_allowed(tsk, cs->cpus_allowed); 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 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_node_allowed_softwall - 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 __GFP_THISNODE is * set, yes, we can always allocate. If node is in our task's mems_allowed, * yes. If it's not a __GFP_HARDWALL request and this node is in the nearest * hardwalled cpuset ancestor to this task's 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_node_allowed_softwall() reduces to * cpuset_node_allowed_hardwall(). Otherwise, cpuset_node_allowed_softwall() * might sleep, and might allow a node from an enclosing cpuset. * * cpuset_node_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_node_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_node_allowed_softwall(int node, gfp_t gfp_mask) { const struct cpuset *cs; /* current cpuset ancestors */ int allowed; /* is allocation in zone z allowed? */ if (in_interrupt() || (gfp_mask & __GFP_THISNODE)) return 1; 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_node_allowed_hardwall - 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 __GFP_THISNODE is * set, yes, we can always allocate. If node is in our task's 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_node_allowed_softwall() variant, above, * this variant requires that the node be in the current task's * 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_node_allowed_hardwall(int node, gfp_t gfp_mask) { if (in_interrupt() || (gfp_mask & __GFP_THISNODE)) 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; return 0; } /** * 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 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 * @task: 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. Must hold task_lock(task) to allow * dereferencing task_cs(task). */ void cpuset_print_task_mems_allowed(struct task_struct *tsk) { struct dentry *dentry; dentry = task_cs(tsk)->css.cgroup->dentry; spin_lock(&cpuset_buffer_lock); snprintf(cpuset_name, CPUSET_NAME_LEN, dentry ? (const char *)dentry->d_name.name : "/"); nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN, tsk->mems_allowed); printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n", tsk->comm, cpuset_name, cpuset_nodelist); spin_unlock(&cpuset_buffer_lock); } /* * 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//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 mems_allowed in /proc//status file. */ void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task) { 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"); }