/* * kernel/cpuset.c * * Processor and Memory placement constraints for sets of tasks. * * Copyright (C) 2003 BULL SA. * Copyright (C) 2004-2006 Silicon Graphics, 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. * * This file is subject to the terms and conditions of the GNU General Public * License. See the file COPYING in the main directory of the Linux * distribution for more details. */ #include <linux/cpu.h> #include <linux/cpumask.h> #include <linux/cpuset.h> #include <linux/err.h> #include <linux/errno.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/interrupt.h> #include <linux/kernel.h> #include <linux/kmod.h> #include <linux/list.h> #include <linux/mempolicy.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/mount.h> #include <linux/namei.h> #include <linux/pagemap.h> #include <linux/proc_fs.h> #include <linux/rcupdate.h> #include <linux/sched.h> #include <linux/seq_file.h> #include <linux/security.h> #include <linux/slab.h> #include <linux/spinlock.h> #include <linux/stat.h> #include <linux/string.h> #include <linux/time.h> #include <linux/backing-dev.h> #include <linux/sort.h> #include <asm/uaccess.h> #include <asm/atomic.h> #include <linux/mutex.h> #define CPUSET_SUPER_MAGIC 0x27e0eb /* * 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; /* 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 { 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 */ /* * Count is atomic so can incr (fork) or decr (exit) without a lock. */ atomic_t count; /* count tasks using this cpuset */ /* * We link our 'sibling' struct into our parents 'children'. * Our children link their 'sibling' into our 'children'. */ struct list_head sibling; /* my parents children */ struct list_head children; /* my children */ struct cpuset *parent; /* my parent */ struct dentry *dentry; /* cpuset fs entry */ /* * 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 */ }; /* bits in struct cpuset flags field */ typedef enum { CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE, CS_MEMORY_MIGRATE, CS_REMOVED, CS_NOTIFY_ON_RELEASE, 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_removed(const struct cpuset *cs) { return test_bit(CS_REMOVED, &cs->flags); } static inline int notify_on_release(const struct cpuset *cs) { return test_bit(CS_NOTIFY_ON_RELEASE, &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, .count = ATOMIC_INIT(0), .sibling = LIST_HEAD_INIT(top_cpuset.sibling), .children = LIST_HEAD_INIT(top_cpuset.children), }; static struct vfsmount *cpuset_mount; static struct super_block *cpuset_sb; /* * 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(manage_mutex); static DEFINE_MUTEX(callback_mutex); /* * A couple of forward declarations required, due to cyclic reference loop: * cpuset_mkdir -> cpuset_create -> cpuset_populate_dir -> cpuset_add_file * -> cpuset_create_file -> cpuset_dir_inode_operations -> cpuset_mkdir. */ static int cpuset_mkdir(struct inode *dir, struct dentry *dentry, int mode); static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry); static struct backing_dev_info cpuset_backing_dev_info = { .ra_pages = 0, /* No readahead */ .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, }; static struct inode *cpuset_new_inode(mode_t mode) { struct inode *inode = new_inode(cpuset_sb); if (inode) { inode->i_mode = mode; inode->i_uid = current->fsuid; inode->i_gid = current->fsgid; inode->i_blocks = 0; inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; inode->i_mapping->backing_dev_info = &cpuset_backing_dev_info; } return inode; } static void cpuset_diput(struct dentry *dentry, struct inode *inode) { /* is dentry a directory ? if so, kfree() associated cpuset */ if (S_ISDIR(inode->i_mode)) { struct cpuset *cs = dentry->d_fsdata; BUG_ON(!(is_removed(cs))); kfree(cs); } iput(inode); } static struct dentry_operations cpuset_dops = { .d_iput = cpuset_diput, }; static struct dentry *cpuset_get_dentry(struct dentry *parent, const char *name) { struct dentry *d = lookup_one_len(name, parent, strlen(name)); if (!IS_ERR(d)) d->d_op = &cpuset_dops; return d; } static void remove_dir(struct dentry *d) { struct dentry *parent = dget(d->d_parent); d_delete(d); simple_rmdir(parent->d_inode, d); dput(parent); } /* * NOTE : the dentry must have been dget()'ed */ static void cpuset_d_remove_dir(struct dentry *dentry) { struct list_head *node; spin_lock(&dcache_lock); node = dentry->d_subdirs.next; while (node != &dentry->d_subdirs) { struct dentry *d = list_entry(node, struct dentry, d_u.d_child); list_del_init(node); if (d->d_inode) { d = dget_locked(d); spin_unlock(&dcache_lock); d_delete(d); simple_unlink(dentry->d_inode, d); dput(d); spin_lock(&dcache_lock); } node = dentry->d_subdirs.next; } list_del_init(&dentry->d_u.d_child); spin_unlock(&dcache_lock); remove_dir(dentry); } static struct super_operations cpuset_ops = { .statfs = simple_statfs, .drop_inode = generic_delete_inode, }; static int cpuset_fill_super(struct super_block *sb, void *unused_data, int unused_silent) { struct inode *inode; struct dentry *root; sb->s_blocksize = PAGE_CACHE_SIZE; sb->s_blocksize_bits = PAGE_CACHE_SHIFT; sb->s_magic = CPUSET_SUPER_MAGIC; sb->s_op = &cpuset_ops; cpuset_sb = sb; inode = cpuset_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR); if (inode) { inode->i_op = &simple_dir_inode_operations; inode->i_fop = &simple_dir_operations; /* directories start off with i_nlink == 2 (for "." entry) */ inc_nlink(inode); } else { return -ENOMEM; } root = d_alloc_root(inode); if (!root) { iput(inode); return -ENOMEM; } sb->s_root = root; return 0; } static int cpuset_get_sb(struct file_system_type *fs_type, int flags, const char *unused_dev_name, void *data, struct vfsmount *mnt) { return get_sb_single(fs_type, flags, data, cpuset_fill_super, mnt); } static struct file_system_type cpuset_fs_type = { .name = "cpuset", .get_sb = cpuset_get_sb, .kill_sb = kill_litter_super, }; /* struct cftype: * * The files in the cpuset filesystem mostly have a very simple read/write * handling, some common function will take care of it. Nevertheless some cases * (read tasks) are special and therefore I define this structure for every * kind of file. * * * When reading/writing to a file: * - the cpuset to use in file->f_path.dentry->d_parent->d_fsdata * - the 'cftype' of the file is file->f_path.dentry->d_fsdata */ struct cftype { char *name; int private; int (*open) (struct inode *inode, struct file *file); ssize_t (*read) (struct file *file, char __user *buf, size_t nbytes, loff_t *ppos); int (*write) (struct file *file, const char __user *buf, size_t nbytes, loff_t *ppos); int (*release) (struct inode *inode, struct file *file); }; static inline struct cpuset *__d_cs(struct dentry *dentry) { return dentry->d_fsdata; } static inline struct cftype *__d_cft(struct dentry *dentry) { return dentry->d_fsdata; } /* * Call with manage_mutex held. Writes path of cpuset into buf. * Returns 0 on success, -errno on error. */ static int cpuset_path(const struct cpuset *cs, char *buf, int buflen) { char *start; start = buf + buflen; *--start = '\0'; for (;;) { int len = cs->dentry->d_name.len; if ((start -= len) < buf) return -ENAMETOOLONG; memcpy(start, cs->dentry->d_name.name, len); cs = cs->parent; if (!cs) break; if (!cs->parent) continue; if (--start < buf) return -ENAMETOOLONG; *start = '/'; } memmove(buf, start, buf + buflen - start); return 0; } /* * Notify userspace when a cpuset is released, by running * /sbin/cpuset_release_agent with the name of the cpuset (path * relative to the root of cpuset file system) as the argument. * * Most likely, this user command will try to rmdir this cpuset. * * This races with the possibility that some other task will be * attached to this cpuset before it is removed, or that some other * user task will 'mkdir' a child cpuset of this cpuset. That's ok. * The presumed 'rmdir' will fail quietly if this cpuset is no longer * unused, and this cpuset will be reprieved from its death sentence, * to continue to serve a useful existence. Next time it's released, * we will get notified again, if it still has 'notify_on_release' set. * * The final arg to call_usermodehelper() is 0, which means don't * wait. The separate /sbin/cpuset_release_agent task is forked by * call_usermodehelper(), then control in this thread returns here, * without waiting for the release agent task. We don't bother to * wait because the caller of this routine has no use for the exit * status of the /sbin/cpuset_release_agent task, so no sense holding * our caller up for that. * * When we had only one cpuset mutex, we had to call this * without holding it, to avoid deadlock when call_usermodehelper() * allocated memory. With two locks, we could now call this while * holding manage_mutex, but we still don't, so as to minimize * the time manage_mutex is held. */ static void cpuset_release_agent(const char *pathbuf) { char *argv[3], *envp[3]; int i; if (!pathbuf) return; i = 0; argv[i++] = "/sbin/cpuset_release_agent"; argv[i++] = (char *)pathbuf; argv[i] = NULL; i = 0; /* minimal command environment */ envp[i++] = "HOME=/"; envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; envp[i] = NULL; call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); kfree(pathbuf); } /* * Either cs->count of using tasks transitioned to zero, or the * cs->children list of child cpusets just became empty. If this * cs is notify_on_release() and now both the user count is zero and * the list of children is empty, prepare cpuset path in a kmalloc'd * buffer, to be returned via ppathbuf, so that the caller can invoke * cpuset_release_agent() with it later on, once manage_mutex is dropped. * Call here with manage_mutex held. * * This check_for_release() routine is responsible for kmalloc'ing * pathbuf. The above cpuset_release_agent() is responsible for * kfree'ing pathbuf. The caller of these routines is responsible * for providing a pathbuf pointer, initialized to NULL, then * calling check_for_release() with manage_mutex held and the address * of the pathbuf pointer, then dropping manage_mutex, then calling * cpuset_release_agent() with pathbuf, as set by check_for_release(). */ static void check_for_release(struct cpuset *cs, char **ppathbuf) { if (notify_on_release(cs) && atomic_read(&cs->count) == 0 && list_empty(&cs->children)) { char *buf; buf = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!buf) return; if (cpuset_path(cs, buf, PAGE_SIZE) < 0) kfree(buf); else *ppathbuf = buf; } } /* * 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 (tsk->cpuset == &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(); cs = rcu_dereference(tsk->cpuset); my_cpusets_mem_gen = cs->mems_generation; rcu_read_unlock(); } if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) { mutex_lock(&callback_mutex); task_lock(tsk); cs = tsk->cpuset; /* 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 cpuset *c, *par; /* Each of our child cpusets must be a subset of us */ list_for_each_entry(c, &cur->children, sibling) { if (!is_cpuset_subset(c, 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(c, &par->children, sibling) { 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; } return 0; } /* * 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; /* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */ if (cs == &top_cpuset) return -EACCES; trialcs = *cs; /* * We allow a cpuset's cpus_allowed to be empty; if it has attached * tasks, we'll catch it later when we validate the change and return * -ENOSPC. */ if (!buf[0] || (buf[0] == '\n' && !buf[1])) { 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); /* cpus_allowed cannot be empty for a cpuset with attached tasks. */ if (atomic_read(&cs->count) && cpus_empty(trialcs.cpus_allowed)) return -ENOSPC; retval = validate_change(cs, &trialcs); if (retval < 0) return retval; mutex_lock(&callback_mutex); cs->cpus_allowed = trialcs.cpus_allowed; mutex_unlock(&callback_mutex); 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(tsk->cpuset, &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 int update_nodemask(struct cpuset *cs, char *buf) { struct cpuset trialcs; nodemask_t oldmem; struct task_struct *g, *p; struct mm_struct **mmarray; int i, n, ntasks; int migrate; int fudge; int retval; /* * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY]; * it's read-only */ if (cs == &top_cpuset) return -EACCES; trialcs = *cs; /* * We allow a cpuset's mems_allowed to be empty; if it has attached * tasks, we'll catch it later when we validate the change and return * -ENOSPC. */ if (!buf[0] || (buf[0] == '\n' && !buf[1])) { nodes_clear(trialcs.mems_allowed); } else { retval = nodelist_parse(buf, trialcs.mems_allowed); if (retval < 0) goto done; if (!nodes_intersects(trialcs.mems_allowed, node_states[N_HIGH_MEMORY])) { /* * error if only memoryless nodes specified. */ retval = -ENOSPC; goto done; } } /* * Exclude memoryless nodes. We know that trialcs.mems_allowed * contains at least one node with memory. */ 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; } /* mems_allowed cannot be empty for a cpuset with attached tasks. */ if (atomic_read(&cs->count) && nodes_empty(trialcs.mems_allowed)) { retval = -ENOSPC; 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); set_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 = atomic_read(&cs->count); /* guess */ ntasks += fudge; mmarray = kmalloc(ntasks * sizeof(*mmarray), GFP_KERNEL); if (!mmarray) goto done; read_lock(&tasklist_lock); /* block fork */ if (atomic_read(&cs->count) <= 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. */ do_each_thread(g, p) { struct mm_struct *mm; if (n >= ntasks) { printk(KERN_WARNING "Cpuset mempolicy rebind incomplete.\n"); continue; } if (p->cpuset != cs) continue; mm = get_task_mm(p); if (!mm) continue; mmarray[n++] = mm; } while_each_thread(g, p); 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); set_cpuset_being_rebound(NULL); retval = 0; done: return retval; } /* * 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_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; 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; mutex_lock(&callback_mutex); cs->flags = trialcs.flags; mutex_unlock(&callback_mutex); 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; } /* * Attack task specified by pid in 'pidbuf' to cpuset 'cs', possibly * writing the path of the old cpuset in 'ppathbuf' if it needs to be * notified on release. * * Call holding manage_mutex. May take callback_mutex and task_lock of * the task 'pid' during call. */ static int attach_task(struct cpuset *cs, char *pidbuf, char **ppathbuf) { pid_t pid; struct task_struct *tsk; struct cpuset *oldcs; cpumask_t cpus; nodemask_t from, to; struct mm_struct *mm; int retval; if (sscanf(pidbuf, "%d", &pid) != 1) return -EIO; if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)) return -ENOSPC; if (pid) { read_lock(&tasklist_lock); tsk = find_task_by_pid(pid); if (!tsk || tsk->flags & PF_EXITING) { read_unlock(&tasklist_lock); return -ESRCH; } get_task_struct(tsk); read_unlock(&tasklist_lock); if ((current->euid) && (current->euid != tsk->uid) && (current->euid != tsk->suid)) { put_task_struct(tsk); return -EACCES; } } else { tsk = current; get_task_struct(tsk); } retval = security_task_setscheduler(tsk, 0, NULL); if (retval) { put_task_struct(tsk); return retval; } mutex_lock(&callback_mutex); task_lock(tsk); oldcs = tsk->cpuset; /* * After getting 'oldcs' cpuset ptr, be sure still not exiting. * If 'oldcs' might be the top_cpuset due to the_top_cpuset_hack * then fail this attach_task(), to avoid breaking top_cpuset.count. */ if (tsk->flags & PF_EXITING) { task_unlock(tsk); mutex_unlock(&callback_mutex); put_task_struct(tsk); return -ESRCH; } atomic_inc(&cs->count); rcu_assign_pointer(tsk->cpuset, cs); task_unlock(tsk); guarantee_online_cpus(cs, &cpus); set_cpus_allowed(tsk, cpus); from = oldcs->mems_allowed; to = cs->mems_allowed; mutex_unlock(&callback_mutex); 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); } put_task_struct(tsk); synchronize_rcu(); if (atomic_dec_and_test(&oldcs->count)) check_for_release(oldcs, ppathbuf); return 0; } /* The various types of files and directories in a cpuset file system */ typedef enum { FILE_ROOT, FILE_DIR, FILE_MEMORY_MIGRATE, FILE_CPULIST, FILE_MEMLIST, FILE_CPU_EXCLUSIVE, FILE_MEM_EXCLUSIVE, FILE_NOTIFY_ON_RELEASE, FILE_MEMORY_PRESSURE_ENABLED, FILE_MEMORY_PRESSURE, FILE_SPREAD_PAGE, FILE_SPREAD_SLAB, FILE_TASKLIST, } cpuset_filetype_t; static ssize_t cpuset_common_file_write(struct file *file, const char __user *userbuf, size_t nbytes, loff_t *unused_ppos) { struct cpuset *cs = __d_cs(file->f_path.dentry->d_parent); struct cftype *cft = __d_cft(file->f_path.dentry); cpuset_filetype_t type = cft->private; char *buffer; char *pathbuf = NULL; int retval = 0; /* Crude upper limit on largest legitimate cpulist user might write. */ if (nbytes > 100 + 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 */ mutex_lock(&manage_mutex); if (is_removed(cs)) { 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_NOTIFY_ON_RELEASE: retval = update_flag(CS_NOTIFY_ON_RELEASE, 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; case FILE_TASKLIST: retval = attach_task(cs, buffer, &pathbuf); break; default: retval = -EINVAL; goto out2; } if (retval == 0) retval = nbytes; out2: mutex_unlock(&manage_mutex); cpuset_release_agent(pathbuf); out1: kfree(buffer); return retval; } static ssize_t cpuset_file_write(struct file *file, const char __user *buf, size_t nbytes, loff_t *ppos) { ssize_t retval = 0; struct cftype *cft = __d_cft(file->f_path.dentry); if (!cft) return -ENODEV; /* special function ? */ if (cft->write) retval = cft->write(file, buf, nbytes, ppos); else retval = cpuset_common_file_write(file, buf, nbytes, ppos); 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 file *file, char __user *buf, size_t nbytes, loff_t *ppos) { struct cftype *cft = __d_cft(file->f_path.dentry); struct cpuset *cs = __d_cs(file->f_path.dentry->d_parent); 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_NOTIFY_ON_RELEASE: *s++ = notify_on_release(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; } static ssize_t cpuset_file_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) { ssize_t retval = 0; struct cftype *cft = __d_cft(file->f_path.dentry); if (!cft) return -ENODEV; /* special function ? */ if (cft->read) retval = cft->read(file, buf, nbytes, ppos); else retval = cpuset_common_file_read(file, buf, nbytes, ppos); return retval; } static int cpuset_file_open(struct inode *inode, struct file *file) { int err; struct cftype *cft; err = generic_file_open(inode, file); if (err) return err; cft = __d_cft(file->f_path.dentry); if (!cft) return -ENODEV; if (cft->open) err = cft->open(inode, file); else err = 0; return err; } static int cpuset_file_release(struct inode *inode, struct file *file) { struct cftype *cft = __d_cft(file->f_path.dentry); if (cft->release) return cft->release(inode, file); return 0; } /* * cpuset_rename - Only allow simple rename of directories in place. */ static int cpuset_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) { if (!S_ISDIR(old_dentry->d_inode->i_mode)) return -ENOTDIR; if (new_dentry->d_inode) return -EEXIST; if (old_dir != new_dir) return -EIO; return simple_rename(old_dir, old_dentry, new_dir, new_dentry); } static const struct file_operations cpuset_file_operations = { .read = cpuset_file_read, .write = cpuset_file_write, .llseek = generic_file_llseek, .open = cpuset_file_open, .release = cpuset_file_release, }; static const struct inode_operations cpuset_dir_inode_operations = { .lookup = simple_lookup, .mkdir = cpuset_mkdir, .rmdir = cpuset_rmdir, .rename = cpuset_rename, }; static int cpuset_create_file(struct dentry *dentry, int mode) { struct inode *inode; if (!dentry) return -ENOENT; if (dentry->d_inode) return -EEXIST; inode = cpuset_new_inode(mode); if (!inode) return -ENOMEM; if (S_ISDIR(mode)) { inode->i_op = &cpuset_dir_inode_operations; inode->i_fop = &simple_dir_operations; /* start off with i_nlink == 2 (for "." entry) */ inc_nlink(inode); } else if (S_ISREG(mode)) { inode->i_size = 0; inode->i_fop = &cpuset_file_operations; } d_instantiate(dentry, inode); dget(dentry); /* Extra count - pin the dentry in core */ return 0; } /* * cpuset_create_dir - create a directory for an object. * cs: the cpuset we create the directory for. * It must have a valid ->parent field * And we are going to fill its ->dentry field. * name: The name to give to the cpuset directory. Will be copied. * mode: mode to set on new directory. */ static int cpuset_create_dir(struct cpuset *cs, const char *name, int mode) { struct dentry *dentry = NULL; struct dentry *parent; int error = 0; parent = cs->parent->dentry; dentry = cpuset_get_dentry(parent, name); if (IS_ERR(dentry)) return PTR_ERR(dentry); error = cpuset_create_file(dentry, S_IFDIR | mode); if (!error) { dentry->d_fsdata = cs; inc_nlink(parent->d_inode); cs->dentry = dentry; } dput(dentry); return error; } static int cpuset_add_file(struct dentry *dir, const struct cftype *cft) { struct dentry *dentry; int error; mutex_lock(&dir->d_inode->i_mutex); dentry = cpuset_get_dentry(dir, cft->name); if (!IS_ERR(dentry)) { error = cpuset_create_file(dentry, 0644 | S_IFREG); if (!error) dentry->d_fsdata = (void *)cft; dput(dentry); } else error = PTR_ERR(dentry); mutex_unlock(&dir->d_inode->i_mutex); return error; } /* * Stuff for reading the 'tasks' file. * * Reading this file can return large amounts of data if a cpuset has * *lots* of attached tasks. So it may need several calls to read(), * but we cannot guarantee that the information we produce is correct * unless we produce it entirely atomically. * * Upon tasks file open(), a struct ctr_struct is allocated, that * will have a pointer to an array (also allocated here). The struct * ctr_struct * is stored in file->private_data. Its resources will * be freed by release() when the file is closed. The array is used * to sprintf the PIDs and then used by read(). */ /* cpusets_tasks_read array */ struct ctr_struct { char *buf; int bufsz; }; /* * Load into 'pidarray' up to 'npids' of the tasks using cpuset 'cs'. * Return actual number of pids loaded. No need to task_lock(p) * when reading out p->cpuset, as we don't really care if it changes * on the next cycle, and we are not going to try to dereference it. */ static int pid_array_load(pid_t *pidarray, int npids, struct cpuset *cs) { int n = 0; struct task_struct *g, *p; read_lock(&tasklist_lock); do_each_thread(g, p) { if (p->cpuset == cs) { if (unlikely(n == npids)) goto array_full; pidarray[n++] = p->pid; } } while_each_thread(g, p); array_full: read_unlock(&tasklist_lock); return n; } static int cmppid(const void *a, const void *b) { return *(pid_t *)a - *(pid_t *)b; } /* * Convert array 'a' of 'npids' pid_t's to a string of newline separated * decimal pids in 'buf'. Don't write more than 'sz' chars, but return * count 'cnt' of how many chars would be written if buf were large enough. */ static int pid_array_to_buf(char *buf, int sz, pid_t *a, int npids) { int cnt = 0; int i; for (i = 0; i < npids; i++) cnt += snprintf(buf + cnt, max(sz - cnt, 0), "%d\n", a[i]); return cnt; } /* * Handle an open on 'tasks' file. Prepare a buffer listing the * process id's of tasks currently attached to the cpuset being opened. * * Does not require any specific cpuset mutexes, and does not take any. */ static int cpuset_tasks_open(struct inode *unused, struct file *file) { struct cpuset *cs = __d_cs(file->f_path.dentry->d_parent); struct ctr_struct *ctr; pid_t *pidarray; int npids; char c; if (!(file->f_mode & FMODE_READ)) return 0; ctr = kmalloc(sizeof(*ctr), GFP_KERNEL); if (!ctr) goto err0; /* * If cpuset gets more users after we read count, we won't have * enough space - tough. This race is indistinguishable to the * caller from the case that the additional cpuset users didn't * show up until sometime later on. */ npids = atomic_read(&cs->count); pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL); if (!pidarray) goto err1; npids = pid_array_load(pidarray, npids, cs); sort(pidarray, npids, sizeof(pid_t), cmppid, NULL); /* Call pid_array_to_buf() twice, first just to get bufsz */ ctr->bufsz = pid_array_to_buf(&c, sizeof(c), pidarray, npids) + 1; ctr->buf = kmalloc(ctr->bufsz, GFP_KERNEL); if (!ctr->buf) goto err2; ctr->bufsz = pid_array_to_buf(ctr->buf, ctr->bufsz, pidarray, npids); kfree(pidarray); file->private_data = ctr; return 0; err2: kfree(pidarray); err1: kfree(ctr); err0: return -ENOMEM; } static ssize_t cpuset_tasks_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) { struct ctr_struct *ctr = file->private_data; return simple_read_from_buffer(buf, nbytes, ppos, ctr->buf, ctr->bufsz); } static int cpuset_tasks_release(struct inode *unused_inode, struct file *file) { struct ctr_struct *ctr; if (file->f_mode & FMODE_READ) { ctr = file->private_data; kfree(ctr->buf); kfree(ctr); } return 0; } /* * for the common functions, 'private' gives the type of file */ static struct cftype cft_tasks = { .name = "tasks", .open = cpuset_tasks_open, .read = cpuset_tasks_read, .release = cpuset_tasks_release, .private = FILE_TASKLIST, }; static struct cftype cft_cpus = { .name = "cpus", .private = FILE_CPULIST, }; static struct cftype cft_mems = { .name = "mems", .private = FILE_MEMLIST, }; static struct cftype cft_cpu_exclusive = { .name = "cpu_exclusive", .private = FILE_CPU_EXCLUSIVE, }; static struct cftype cft_mem_exclusive = { .name = "mem_exclusive", .private = FILE_MEM_EXCLUSIVE, }; static struct cftype cft_notify_on_release = { .name = "notify_on_release", .private = FILE_NOTIFY_ON_RELEASE, }; static struct cftype cft_memory_migrate = { .name = "memory_migrate", .private = FILE_MEMORY_MIGRATE, }; static struct cftype cft_memory_pressure_enabled = { .name = "memory_pressure_enabled", .private = FILE_MEMORY_PRESSURE_ENABLED, }; static struct cftype cft_memory_pressure = { .name = "memory_pressure", .private = FILE_MEMORY_PRESSURE, }; static struct cftype cft_spread_page = { .name = "memory_spread_page", .private = FILE_SPREAD_PAGE, }; static struct cftype cft_spread_slab = { .name = "memory_spread_slab", .private = FILE_SPREAD_SLAB, }; static int cpuset_populate_dir(struct dentry *cs_dentry) { int err; if ((err = cpuset_add_file(cs_dentry, &cft_cpus)) < 0) return err; if ((err = cpuset_add_file(cs_dentry, &cft_mems)) < 0) return err; if ((err = cpuset_add_file(cs_dentry, &cft_cpu_exclusive)) < 0) return err; if ((err = cpuset_add_file(cs_dentry, &cft_mem_exclusive)) < 0) return err; if ((err = cpuset_add_file(cs_dentry, &cft_notify_on_release)) < 0) return err; if ((err = cpuset_add_file(cs_dentry, &cft_memory_migrate)) < 0) return err; if ((err = cpuset_add_file(cs_dentry, &cft_memory_pressure)) < 0) return err; if ((err = cpuset_add_file(cs_dentry, &cft_spread_page)) < 0) return err; if ((err = cpuset_add_file(cs_dentry, &cft_spread_slab)) < 0) return err; if ((err = cpuset_add_file(cs_dentry, &cft_tasks)) < 0) return err; return 0; } /* * 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 long cpuset_create(struct cpuset *parent, const char *name, int mode) { struct cpuset *cs; int err; cs = kmalloc(sizeof(*cs), GFP_KERNEL); if (!cs) return -ENOMEM; mutex_lock(&manage_mutex); cpuset_update_task_memory_state(); cs->flags = 0; if (notify_on_release(parent)) set_bit(CS_NOTIFY_ON_RELEASE, &cs->flags); if (is_spread_page(parent)) set_bit(CS_SPREAD_PAGE, &cs->flags); if (is_spread_slab(parent)) set_bit(CS_SPREAD_SLAB, &cs->flags); cs->cpus_allowed = CPU_MASK_NONE; cs->mems_allowed = NODE_MASK_NONE; atomic_set(&cs->count, 0); INIT_LIST_HEAD(&cs->sibling); INIT_LIST_HEAD(&cs->children); cs->mems_generation = cpuset_mems_generation++; fmeter_init(&cs->fmeter); cs->parent = parent; mutex_lock(&callback_mutex); list_add(&cs->sibling, &cs->parent->children); number_of_cpusets++; mutex_unlock(&callback_mutex); err = cpuset_create_dir(cs, name, mode); if (err < 0) goto err; /* * Release manage_mutex before cpuset_populate_dir() because it * will down() this new directory's i_mutex and if we race with * another mkdir, we might deadlock. */ mutex_unlock(&manage_mutex); err = cpuset_populate_dir(cs->dentry); /* If err < 0, we have a half-filled directory - oh well ;) */ return 0; err: list_del(&cs->sibling); mutex_unlock(&manage_mutex); kfree(cs); return err; } static int cpuset_mkdir(struct inode *dir, struct dentry *dentry, int mode) { struct cpuset *c_parent = dentry->d_parent->d_fsdata; /* the vfs holds inode->i_mutex already */ return cpuset_create(c_parent, dentry->d_name.name, mode | S_IFDIR); } static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry) { struct cpuset *cs = dentry->d_fsdata; struct dentry *d; struct cpuset *parent; char *pathbuf = NULL; /* the vfs holds both inode->i_mutex already */ mutex_lock(&manage_mutex); cpuset_update_task_memory_state(); if (atomic_read(&cs->count) > 0) { mutex_unlock(&manage_mutex); return -EBUSY; } if (!list_empty(&cs->children)) { mutex_unlock(&manage_mutex); return -EBUSY; } parent = cs->parent; mutex_lock(&callback_mutex); set_bit(CS_REMOVED, &cs->flags); list_del(&cs->sibling); /* delete my sibling from parent->children */ spin_lock(&cs->dentry->d_lock); d = dget(cs->dentry); cs->dentry = NULL; spin_unlock(&d->d_lock); cpuset_d_remove_dir(d); dput(d); number_of_cpusets--; mutex_unlock(&callback_mutex); if (list_empty(&parent->children)) check_for_release(parent, &pathbuf); mutex_unlock(&manage_mutex); cpuset_release_agent(pathbuf); return 0; } /* * 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) { struct task_struct *tsk = current; tsk->cpuset = &top_cpuset; tsk->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) { struct dentry *root; int err; 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++; init_task.cpuset = &top_cpuset; err = register_filesystem(&cpuset_fs_type); if (err < 0) goto out; cpuset_mount = kern_mount(&cpuset_fs_type); if (IS_ERR(cpuset_mount)) { printk(KERN_ERR "cpuset: could not mount!\n"); err = PTR_ERR(cpuset_mount); cpuset_mount = NULL; goto out; } root = cpuset_mount->mnt_sb->s_root; root->d_fsdata = &top_cpuset; inc_nlink(root->d_inode); top_cpuset.dentry = root; root->d_inode->i_op = &cpuset_dir_inode_operations; number_of_cpusets = 1; err = cpuset_populate_dir(root); /* memory_pressure_enabled is in root cpuset only */ if (err == 0) err = cpuset_add_file(root, &cft_memory_pressure_enabled); out: return err; } /* * 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 cpuset *c; /* Each of our child cpusets mems must be online */ list_for_each_entry(c, &cur->children, sibling) { 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) { mutex_lock(&manage_mutex); 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); mutex_unlock(&manage_mutex); } /* * 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 *nb, unsigned long phase, void *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_fork - attach newly forked task to its parents cpuset. * @tsk: pointer to task_struct of forking parent process. * * Description: A task inherits its parent's cpuset at fork(). * * A pointer to the shared cpuset was automatically copied in fork.c * by dup_task_struct(). However, we ignore that copy, since it was * not made under the protection of task_lock(), so might no longer be * a valid cpuset pointer. attach_task() might have already changed * current->cpuset, allowing the previously referenced cpuset to * be removed and freed. Instead, we task_lock(current) and copy * its present value of current->cpuset for our freshly forked child. * * At the point that cpuset_fork() is called, 'current' is the parent * task, and the passed argument 'child' points to the child task. **/ void cpuset_fork(struct task_struct *child) { task_lock(current); child->cpuset = current->cpuset; atomic_inc(&child->cpuset->count); task_unlock(current); } /** * cpuset_exit - detach cpuset from exiting task * @tsk: pointer to task_struct of exiting process * * Description: Detach cpuset from @tsk and release it. * * Note that cpusets marked notify_on_release force every task in * them to take the global manage_mutex mutex when exiting. * This could impact scaling on very large systems. Be reluctant to * use notify_on_release cpusets where very high task exit scaling * is required on large systems. * * Don't even think about derefencing 'cs' after the cpuset use count * goes to zero, except inside a critical section guarded by manage_mutex * or callback_mutex. Otherwise a zero cpuset use count is a license to * any other task to nuke the cpuset immediately, via cpuset_rmdir(). * * This routine has to take manage_mutex, not callback_mutex, because * it is holding that mutex while calling check_for_release(), * which calls kmalloc(), so can't be called holding callback_mutex(). * * the_top_cpuset_hack: * * Set the exiting tasks cpuset to the root cpuset (top_cpuset). * * Don't leave a task unable to allocate memory, as that is an * accident waiting to happen should someone add a callout in * do_exit() after the cpuset_exit() call that might allocate. * If a task tries to allocate memory with an invalid cpuset, * it will oops in cpuset_update_task_memory_state(). * * We call cpuset_exit() while the task is still competent to * handle notify_on_release(), then leave the task attached to * the root cpuset (top_cpuset) for the remainder of its exit. * * To do this properly, we would increment the reference count on * top_cpuset, and near the very end of the kernel/exit.c do_exit() * code we would add a second cpuset function call, to drop that * reference. This would just create an unnecessary hot spot on * the top_cpuset reference count, to no avail. * * Normally, holding a reference to a cpuset without bumping its * count is unsafe. The cpuset could go away, or someone could * attach us to a different cpuset, decrementing the count on * the first cpuset that we never incremented. But in this case, * top_cpuset isn't going away, and either task has PF_EXITING set, * which wards off any attach_task() attempts, or task is a failed * fork, never visible to attach_task. * * Another way to do this would be to set the cpuset pointer * to NULL here, and check in cpuset_update_task_memory_state() * for a NULL pointer. This hack avoids that NULL check, for no * cost (other than this way too long comment ;). **/ void cpuset_exit(struct task_struct *tsk) { struct cpuset *cs; task_lock(current); cs = tsk->cpuset; tsk->cpuset = &top_cpuset; /* the_top_cpuset_hack - see above */ task_unlock(current); if (notify_on_release(cs)) { char *pathbuf = NULL; mutex_lock(&manage_mutex); if (atomic_dec_and_test(&cs->count)) check_for_release(cs, &pathbuf); mutex_unlock(&manage_mutex); cpuset_release_agent(pathbuf); } else { atomic_dec(&cs->count); } } /** * 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); task_lock(tsk); guarantee_online_cpus(tsk->cpuset, &mask); task_unlock(tsk); mutex_unlock(&callback_mutex); 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(tsk->cpuset, &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(current->cpuset); 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) { struct cpuset *cs; task_lock(current); cs = current->cpuset; fmeter_markevent(&cs->fmeter); task_unlock(current); } /* * proc_cpuset_show() * - Print tasks cpuset path into seq_file. * - Used for /proc/<pid>/cpuset. * - No need to task_lock(tsk) on this tsk->cpuset reference, as it * doesn't really matter if tsk->cpuset changes after we read it, * and we take 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 *v) { struct pid *pid; struct task_struct *tsk; char *buf; 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; mutex_lock(&manage_mutex); retval = cpuset_path(tsk->cpuset, buf, PAGE_SIZE); if (retval < 0) goto out_unlock; seq_puts(m, buf); seq_putc(m, '\n'); out_unlock: mutex_unlock(&manage_mutex); 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, }; /* Display task cpus_allowed, mems_allowed in /proc/<pid>/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; }