/* * 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 * * 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 /* * 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; /* Retrieve the cpuset from a cgroup */ 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; }; /* 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); } /* bits in struct cpuset flags field */ typedef enum { CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE, 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_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 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 anothers 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 cpuset_mems_generation is guarded by manage_mutex, * 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, }; /* * We have two global cpuset mutexes below. They can nest. * It is ok to first take manage_mutex, then nest callback_mutex. We also * require taking task_lock() when dereferencing a tasks 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 manage_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 manage_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. * * Any task can increment and decrement the count field without lock. * So in general, code holding manage_mutex or callback_mutex can't rely * on the count field not changing. However, if the count goes to * zero, then only attach_task(), which holds both mutexes, can * increment it again. Because a count of zero means that no tasks * are currently attached, therefore there is no way a task attached * to that cpuset can fork (the other way to increment the count). * So code holding manage_mutex or callback_mutex can safely assume that * if the count is zero, it will stay zero. Similarly, if a task * holds manage_mutex or callback_mutex on a cpuset with zero count, it * knows that the cpuset won't be removed, as cpuset_rmdir() needs * both of those mutexes. * * The cpuset_common_file_write handler for operations that modify * the cpuset hierarchy holds manage_mutex across the entire operation, * single threading all such cpuset modifications across the system. * * 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. * * The fork and exit callbacks cpuset_fork() and cpuset_exit(), don't * (usually) take either mutex. These are the two most performance * critical pieces of code here. The exception occurs on cpuset_exit(), * when a task in a notify_on_release cpuset exits. Then manage_mutex * is taken, and if the cpuset count is zero, a usermode call made * to /sbin/cpuset_release_agent with the name of the cpuset (path * relative to the root of cpuset file system) as the argument. * * A cpuset can only be deleted if both its 'count' of using tasks * is zero, and its list of 'children' cpusets is empty. Since all * tasks in the system use _some_ cpuset, and since there is always at * least one task in the system (init), therefore, top_cpuset * always has either children cpusets and/or using tasks. So we don't * need a special hack to ensure that top_cpuset cannot be deleted. * * The above "Tale of Two Semaphores" would be complete, but for: * * The task_lock() exception * * The need for this exception arises from the action of attach_task(), * which overwrites one tasks cpuset pointer with another. It does * so using both mutexes, however there are several performance * critical places that need to reference task->cpuset without the * expense of grabbing a system global mutex. Therefore except as * noted below, when dereferencing or, as in attach_task(), modifying * a tasks cpuset pointer we use task_lock(), which acts on a spinlock * (task->alloc_lock) already in the task_struct routinely used for * such matters. * * P.S. One more locking exception. RCU is used to guard the * update of a tasks cpuset pointer by attach_task() and the * access of task->cpuset->mems_generation via that pointer in * the routine cpuset_update_task_memory_state(). */ 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 manage_mutex held. Thanks in part to * 'the_top_cpuset_hack', the tasks cpuset pointer will never * be NULL. This routine also might acquire callback_mutex and * current->mm->mmap_sem 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 by attach_task(), * 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(current)->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 manage_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 * manage_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 rebuild_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); } /* * rebuild_sched_domains() * * If the flag 'sched_load_balance' of any cpuset with non-empty * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset * which has that flag enabled, or if any cpuset with a non-empty * 'cpus' is removed, then call this routine to rebuild the * scheduler's dynamic sched domains. * * This routine builds a partial partition of the systems CPUs * (the set of non-overlappping cpumask_t's in the array 'part' * below), and passes that partial partition to the kernel/sched.c * partition_sched_domains() routine, which will rebuild the * schedulers load balancing domains (sched domains) as specified * by that partial partition. A 'partial partition' is a set of * non-overlapping subsets whose union is a subset of that set. * * 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. * * Call with cgroup_mutex held. May take callback_mutex during * call due to the kfifo_alloc() and kmalloc() calls. May nest * a call to the get_online_cpus()/put_online_cpus() pair. * Must not be called holding callback_mutex, because we must not * call get_online_cpus() while holding callback_mutex. Elsewhere * the kernel nests callback_mutex inside get_online_cpus() calls. * So the reverse nesting would risk an ABBA deadlock. * * The three key local variables below are: * q - a kfifo 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 void rebuild_sched_domains(void) { struct kfifo *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 */ int ndoms; /* number of sched domains in result */ int nslot; /* next empty doms[] cpumask_t slot */ q = NULL; csa = NULL; doms = NULL; /* Special case for the 99% of systems with one, full, sched domain */ if (is_sched_load_balance(&top_cpuset)) { ndoms = 1; doms = kmalloc(sizeof(cpumask_t), GFP_KERNEL); if (!doms) goto rebuild; *doms = top_cpuset.cpus_allowed; goto rebuild; } q = kfifo_alloc(number_of_cpusets * sizeof(cp), GFP_KERNEL, NULL); if (IS_ERR(q)) goto done; csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL); if (!csa) goto done; csn = 0; cp = &top_cpuset; __kfifo_put(q, (void *)&cp, sizeof(cp)); while (__kfifo_get(q, (void *)&cp, sizeof(cp))) { struct cgroup *cont; struct cpuset *child; /* scans child cpusets of cp */ if (is_sched_load_balance(cp)) csa[csn++] = cp; list_for_each_entry(cont, &cp->css.cgroup->children, sibling) { child = cgroup_cs(cont); __kfifo_put(q, (void *)&child, sizeof(cp)); } } 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; } } } /* Convert to */ doms = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL); if (!doms) goto rebuild; for (nslot = 0, i = 0; i < csn; i++) { struct cpuset *a = csa[i]; int apn = a->pn; if (apn >= 0) { cpumask_t *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); for (j = i; j < csn; j++) { struct cpuset *b = csa[j]; if (apn == b->pn) { cpus_or(*dp, *dp, b->cpus_allowed); b->pn = -1; } } nslot++; } } BUG_ON(nslot != ndoms); rebuild: /* Have scheduler rebuild sched domains */ get_online_cpus(); partition_sched_domains(ndoms, doms); put_online_cpus(); done: if (q && !IS_ERR(q)) kfifo_free(q); kfree(csa); /* Don't kfree(doms) -- partition_sched_domains() does that. */ } static inline int started_after_time(struct task_struct *t1, struct timespec *time, struct task_struct *t2) { int start_diff = timespec_compare(&t1->start_time, time); if (start_diff > 0) { return 1; } else if (start_diff < 0) { return 0; } else { /* * Arbitrarily, if two processes started at the same * time, we'll say that the lower pointer value * started first. Note that t2 may have exited by now * so this may not be a valid pointer any longer, but * that's fine - it still serves to distinguish * between two tasks started (effectively) * simultaneously. */ return t1 > t2; } } static inline int started_after(void *p1, void *p2) { struct task_struct *t1 = p1; struct task_struct *t2 = p2; return started_after_time(t1, &t2->start_time, t2); } /* * Call with manage_mutex held. May take callback_mutex during call. */ static int update_cpumask(struct cpuset *cs, char *buf) { struct cpuset trialcs; int retval, i; int is_load_balanced; struct cgroup_iter it; struct cgroup *cgrp = cs->css.cgroup; struct task_struct *p, *dropped; /* Never dereference latest_task, since it's not refcounted */ struct task_struct *latest_task = NULL; struct ptr_heap heap; struct timespec latest_time = { 0, 0 }; /* 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 iff there are no tasks in the cpuset. * Since cpulist_parse() fails on an empty mask, we special case * that parsing. The validate_change() call ensures that cpusets * with tasks have cpus. */ buf = strstrip(buf); if (!*buf) { cpus_clear(trialcs.cpus_allowed); } else { retval = cpulist_parse(buf, trialcs.cpus_allowed); if (retval < 0) return retval; } cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map); 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, &started_after); 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); again: /* * Scan tasks in the cpuset, and update the cpumasks of any * that need an update. Since we can't call set_cpus_allowed() * while holding tasklist_lock, gather tasks to be processed * in a heap structure. If the statically-sized heap fills up, * overflow tasks that started later, and in future iterations * only consider tasks that started after the latest task in * the previous pass. This guarantees forward progress and * that we don't miss any tasks */ heap.size = 0; cgroup_iter_start(cgrp, &it); while ((p = cgroup_iter_next(cgrp, &it))) { /* Only affect tasks that don't have the right cpus_allowed */ if (cpus_equal(p->cpus_allowed, cs->cpus_allowed)) continue; /* * Only process tasks that started after the last task * we processed */ if (!started_after_time(p, &latest_time, latest_task)) continue; dropped = heap_insert(&heap, p); if (dropped == NULL) { get_task_struct(p); } else if (dropped != p) { get_task_struct(p); put_task_struct(dropped); } } cgroup_iter_end(cgrp, &it); if (heap.size) { for (i = 0; i < heap.size; i++) { struct task_struct *p = heap.ptrs[i]; if (i == 0) { latest_time = p->start_time; latest_task = p; } set_cpus_allowed(p, cs->cpus_allowed); put_task_struct(p); } /* * If we had to process any tasks at all, scan again * in case some of them were in the middle of forking * children that didn't notice the new cpumask * restriction. Not the most efficient way to do it, * but it avoids having to take callback_mutex in the * fork path */ goto again; } heap_free(&heap); if (is_load_balanced) 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 manage_mutex, so our current->cpuset won't change * during this call, as manage_mutex holds off any attach_task() * 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 tasks 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); } /* * 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 manage_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 void *cpuset_being_rebound; static int update_nodemask(struct cpuset *cs, char *buf) { struct cpuset trialcs; nodemask_t oldmem; struct task_struct *p; struct mm_struct **mmarray; int i, n, ntasks; int migrate; int fudge; int retval; struct cgroup_iter it; /* * 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. */ buf = strstrip(buf); if (!*buf) { nodes_clear(trialcs.mems_allowed); } else { retval = nodelist_parse(buf, trialcs.mems_allowed); if (retval < 0) goto done; } nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_states[N_HIGH_MEMORY]); 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); cpuset_being_rebound = cs; /* causes mpol_copy() 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_copy() * cpuset_being_rebound check will catch such forks, and rebind * their vma mempolicies too. Because we still hold the global * cpuset manage_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 vma's to this cpusets new mems_allowed. */ kfree(mmarray); cpuset_being_rebound = NULL; retval = 0; done: return retval; } int current_cpuset_is_being_rebound(void) { return task_cs(current) == cpuset_being_rebound; } /* * Call with manage_mutex held. */ static int update_memory_pressure_enabled(struct cpuset *cs, char *buf) { if (simple_strtoul(buf, NULL, 10) != 0) cpuset_memory_pressure_enabled = 1; else cpuset_memory_pressure_enabled = 0; return 0; } /* * update_flag - read a 0 or a 1 in a file and update associated flag * bit: the bit to update (CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE, * CS_SCHED_LOAD_BALANCE, * CS_NOTIFY_ON_RELEASE, CS_MEMORY_MIGRATE, * CS_SPREAD_PAGE, CS_SPREAD_SLAB) * cs: the cpuset to update * buf: the buffer where we read the 0 or 1 * * Call with manage_mutex held. */ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, char *buf) { int turning_on; struct cpuset trialcs; int err; int cpus_nonempty, balance_flag_changed; turning_on = (simple_strtoul(buf, NULL, 10) != 0); 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; cpus_nonempty = !cpus_empty(trialcs.cpus_allowed); 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_nonempty && balance_flag_changed) 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; } 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; 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); mutex_lock(&callback_mutex); guarantee_online_cpus(cs, &cpus); set_cpus_allowed(tsk, cpus); mutex_unlock(&callback_mutex); 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_SCHED_LOAD_BALANCE, FILE_MEMORY_PRESSURE_ENABLED, FILE_MEMORY_PRESSURE, FILE_SPREAD_PAGE, FILE_SPREAD_SLAB, } cpuset_filetype_t; static ssize_t cpuset_common_file_write(struct cgroup *cont, struct cftype *cft, struct file *file, const char __user *userbuf, size_t nbytes, loff_t *unused_ppos) { struct cpuset *cs = cgroup_cs(cont); cpuset_filetype_t type = cft->private; char *buffer; int retval = 0; /* Crude upper limit on largest legitimate cpulist user might write. */ if (nbytes > 100U + 6 * max(NR_CPUS, MAX_NUMNODES)) return -E2BIG; /* +1 for nul-terminator */ if ((buffer = kmalloc(nbytes + 1, GFP_KERNEL)) == 0) return -ENOMEM; if (copy_from_user(buffer, userbuf, nbytes)) { retval = -EFAULT; goto out1; } buffer[nbytes] = 0; /* nul-terminate */ cgroup_lock(); if (cgroup_is_removed(cont)) { retval = -ENODEV; goto out2; } switch (type) { case FILE_CPULIST: retval = update_cpumask(cs, buffer); break; case FILE_MEMLIST: retval = update_nodemask(cs, buffer); break; case FILE_CPU_EXCLUSIVE: retval = update_flag(CS_CPU_EXCLUSIVE, cs, buffer); break; case FILE_MEM_EXCLUSIVE: retval = update_flag(CS_MEM_EXCLUSIVE, cs, buffer); break; case FILE_SCHED_LOAD_BALANCE: retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, buffer); break; case FILE_MEMORY_MIGRATE: retval = update_flag(CS_MEMORY_MIGRATE, cs, buffer); break; case FILE_MEMORY_PRESSURE_ENABLED: retval = update_memory_pressure_enabled(cs, buffer); break; case FILE_MEMORY_PRESSURE: retval = -EACCES; break; case FILE_SPREAD_PAGE: retval = update_flag(CS_SPREAD_PAGE, cs, buffer); cs->mems_generation = cpuset_mems_generation++; break; case FILE_SPREAD_SLAB: retval = update_flag(CS_SPREAD_SLAB, cs, buffer); cs->mems_generation = cpuset_mems_generation++; break; default: retval = -EINVAL; goto out2; } if (retval == 0) retval = nbytes; out2: cgroup_unlock(); out1: kfree(buffer); 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; case FILE_CPU_EXCLUSIVE: *s++ = is_cpu_exclusive(cs) ? '1' : '0'; break; case FILE_MEM_EXCLUSIVE: *s++ = is_mem_exclusive(cs) ? '1' : '0'; break; case FILE_SCHED_LOAD_BALANCE: *s++ = is_sched_load_balance(cs) ? '1' : '0'; break; case FILE_MEMORY_MIGRATE: *s++ = is_memory_migrate(cs) ? '1' : '0'; break; case FILE_MEMORY_PRESSURE_ENABLED: *s++ = cpuset_memory_pressure_enabled ? '1' : '0'; break; case FILE_MEMORY_PRESSURE: s += sprintf(s, "%d", fmeter_getrate(&cs->fmeter)); break; case FILE_SPREAD_PAGE: *s++ = is_spread_page(cs) ? '1' : '0'; break; case FILE_SPREAD_SLAB: *s++ = is_spread_slab(cs) ? '1' : '0'; 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; } /* * for the common functions, 'private' gives the type of file */ static struct cftype cft_cpus = { .name = "cpus", .read = cpuset_common_file_read, .write = cpuset_common_file_write, .private = FILE_CPULIST, }; static struct cftype cft_mems = { .name = "mems", .read = cpuset_common_file_read, .write = cpuset_common_file_write, .private = FILE_MEMLIST, }; static struct cftype cft_cpu_exclusive = { .name = "cpu_exclusive", .read = cpuset_common_file_read, .write = cpuset_common_file_write, .private = FILE_CPU_EXCLUSIVE, }; static struct cftype cft_mem_exclusive = { .name = "mem_exclusive", .read = cpuset_common_file_read, .write = cpuset_common_file_write, .private = FILE_MEM_EXCLUSIVE, }; static struct cftype cft_sched_load_balance = { .name = "sched_load_balance", .read = cpuset_common_file_read, .write = cpuset_common_file_write, .private = FILE_SCHED_LOAD_BALANCE, }; static struct cftype cft_memory_migrate = { .name = "memory_migrate", .read = cpuset_common_file_read, .write = cpuset_common_file_write, .private = FILE_MEMORY_MIGRATE, }; static struct cftype cft_memory_pressure_enabled = { .name = "memory_pressure_enabled", .read = cpuset_common_file_read, .write = cpuset_common_file_write, .private = FILE_MEMORY_PRESSURE_ENABLED, }; static struct cftype cft_memory_pressure = { .name = "memory_pressure", .read = cpuset_common_file_read, .write = cpuset_common_file_write, .private = FILE_MEMORY_PRESSURE, }; static struct cftype cft_spread_page = { .name = "memory_spread_page", .read = cpuset_common_file_read, .write = cpuset_common_file_write, .private = FILE_SPREAD_PAGE, }; static struct cftype cft_spread_slab = { .name = "memory_spread_slab", .read = cpuset_common_file_read, .write = cpuset_common_file_write, .private = FILE_SPREAD_SLAB, }; static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont) { int err; if ((err = cgroup_add_file(cont, ss, &cft_cpus)) < 0) return err; if ((err = cgroup_add_file(cont, ss, &cft_mems)) < 0) return err; if ((err = cgroup_add_file(cont, ss, &cft_cpu_exclusive)) < 0) return err; if ((err = cgroup_add_file(cont, ss, &cft_mem_exclusive)) < 0) return err; if ((err = cgroup_add_file(cont, ss, &cft_memory_migrate)) < 0) return err; if ((err = cgroup_add_file(cont, ss, &cft_sched_load_balance)) < 0) return err; if ((err = cgroup_add_file(cont, ss, &cft_memory_pressure)) < 0) return err; if ((err = cgroup_add_file(cont, ss, &cft_spread_page)) < 0) return err; if ((err = cgroup_add_file(cont, ss, &cft_spread_slab)) < 0) return err; /* memory_pressure_enabled is in root cpuset only */ if (err == 0 && !cont->parent) err = cgroup_add_file(cont, ss, &cft_memory_pressure_enabled); return 0; } /* * 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. */ 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 * parent: cpuset that will be parent of the new cpuset. * name: name of the new cpuset. Will be strcpy'ed. * mode: mode to set on new inode * * Must be called with the mutex on the parent inode held */ 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); cs->cpus_allowed = CPU_MASK_NONE; cs->mems_allowed = NODE_MASK_NONE; cs->mems_generation = cpuset_mems_generation++; fmeter_init(&cs->fmeter); cs->parent = parent; number_of_cpusets++; return &cs->css ; } /* * Locking note on the strange update_flag() call below: * * If the cpuset being removed has its flag 'sched_load_balance' * enabled, then simulate turning sched_load_balance off, which * will call rebuild_sched_domains(). The get_online_cpus() * call in rebuild_sched_domains() must not be made while holding * callback_mutex. Elsewhere the kernel nests callback_mutex inside * get_online_cpus() calls. So the reverse nesting would risk an * ABBA deadlock. */ 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; top_cpuset.cpus_allowed = CPU_MASK_ALL; top_cpuset.mems_allowed = NODE_MASK_ALL; fmeter_init(&top_cpuset.fmeter); top_cpuset.mems_generation = cpuset_mems_generation++; set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags); err = register_filesystem(&cpuset_fs_type); if (err < 0) return err; number_of_cpusets = 1; return 0; } /* * If common_cpu_mem_hotplug_unplug(), below, unplugs 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 the guarantee_online_cpus() * or guarantee_online_mems() code will use that emptied cpusets * parent online CPUs or nodes. Cpusets that were already empty of * CPUs or nodes are left empty. * * This routine is intentionally inefficient in a couple of regards. * It will check all cpusets in a subtree even if the top cpuset of * the subtree has no offline CPUs or nodes. It checks both CPUs and * nodes, even though the caller could have been coded to know that * only one of CPUs or nodes needed to be checked on a given call. * This was done to minimize text size rather than cpu cycles. * * Call with both manage_mutex and callback_mutex held. * * Recursive, on depth of cpuset subtree. */ static void guarantee_online_cpus_mems_in_subtree(const struct cpuset *cur) { struct cgroup *cont; struct cpuset *c; /* Each of our child cpusets mems must be online */ list_for_each_entry(cont, &cur->css.cgroup->children, sibling) { c = cgroup_cs(cont); guarantee_online_cpus_mems_in_subtree(c); if (!cpus_empty(c->cpus_allowed)) guarantee_online_cpus(c, &c->cpus_allowed); if (!nodes_empty(c->mems_allowed)) guarantee_online_mems(c, &c->mems_allowed); } } /* * The cpus_allowed and mems_allowed nodemasks in the top_cpuset track * cpu_online_map and node_states[N_HIGH_MEMORY]. Force the top cpuset to * track what's online after any CPU or memory node hotplug or unplug * event. * * To ensure that we don't remove a CPU or node from the top cpuset * that is currently in use by a child cpuset (which would violate * the rule that cpusets must be subsets of their parent), we first * call the recursive routine guarantee_online_cpus_mems_in_subtree(). * * Since there are two callers of this routine, one for CPU hotplug * events and one for memory node hotplug events, we could have coded * two separate routines here. We code it as a single common routine * in order to minimize text size. */ static void common_cpu_mem_hotplug_unplug(void) { cgroup_lock(); mutex_lock(&callback_mutex); guarantee_online_cpus_mems_in_subtree(&top_cpuset); top_cpuset.cpus_allowed = cpu_online_map; top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; mutex_unlock(&callback_mutex); cgroup_unlock(); } /* * 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. */ static int cpuset_handle_cpuhp(struct notifier_block *unused_nb, unsigned long phase, void *unused_cpu) { if (phase == CPU_DYING || phase == CPU_DYING_FROZEN) return NOTIFY_DONE; common_cpu_mem_hotplug_unplug(); return 0; } #ifdef CONFIG_MEMORY_HOTPLUG /* * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY]. * Call this routine anytime after you change * node_states[N_HIGH_MEMORY]. * See also the previous routine cpuset_handle_cpuhp(). */ void cpuset_track_online_nodes(void) { common_cpu_mem_hotplug_unplug(); } #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_handle_cpuhp, 0); } /** * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset. * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed. * * 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. **/ cpumask_t cpuset_cpus_allowed(struct task_struct *tsk) { cpumask_t mask; mutex_lock(&callback_mutex); mask = cpuset_cpus_allowed_locked(tsk); mutex_unlock(&callback_mutex); return mask; } /** * cpuset_cpus_allowed_locked - return cpus_allowed mask from a tasks cpuset. * Must be called with callback_mutex held. **/ cpumask_t cpuset_cpus_allowed_locked(struct task_struct *tsk) { cpumask_t mask; task_lock(tsk); guarantee_online_cpus(task_cs(tsk), &mask); task_unlock(tsk); return mask; } void cpuset_init_current_mems_allowed(void) { current->mems_allowed = NODE_MASK_ALL; } /** * 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_zonelist_valid_mems_allowed - check zonelist vs. curremt mems_allowed * @zl: the zonelist to be checked * * Are any of the nodes on zonelist zl allowed in current->mems_allowed? */ int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl) { int i; for (i = 0; zl->zones[i]; i++) { int nid = zone_to_nid(zl->zones[i]); if (node_isset(nid, current->mems_allowed)) return 1; } return 0; } /* * nearest_exclusive_ancestor() - Returns the nearest mem_exclusive * ancestor to the specified cpuset. Call holding callback_mutex. * If no ancestor is mem_exclusive (an unusual configuration), then * returns the root cpuset. */ static const struct cpuset *nearest_exclusive_ancestor(const struct cpuset *cs) { while (!is_mem_exclusive(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 * mem_exclusive 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 mem_exclusive 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 mem_exclusive 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_exclusive_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//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 manage_mutex, keeping attach_task() from changing it * anyway. No need to check that tsk->cpuset != NULL, thanks to * the_top_cpuset_hack in cpuset_exit(), which sets an exiting tasks * cpuset to top_cpuset. */ 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//status file. */ char *cpuset_task_status_allowed(struct task_struct *task, char *buffer) { buffer += sprintf(buffer, "Cpus_allowed:\t"); buffer += cpumask_scnprintf(buffer, PAGE_SIZE, task->cpus_allowed); buffer += sprintf(buffer, "\n"); buffer += sprintf(buffer, "Mems_allowed:\t"); buffer += nodemask_scnprintf(buffer, PAGE_SIZE, task->mems_allowed); buffer += sprintf(buffer, "\n"); return buffer; }