/* * kernel/cpuset.c * * Processor and Memory placement constraints for sets of tasks. * * Copyright (C) 2003 BULL SA. * Copyright (C) 2004 Silicon Graphics, Inc. * * Portions derived from Patrick Mochel's sysfs code. * sysfs is Copyright (c) 2001-3 Patrick Mochel * Portions Copyright (c) 2004 Silicon Graphics, Inc. * * 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 #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 #define CPUSET_SUPER_MAGIC 0x27e0eb /* 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 } 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); } /* * Increment this atomic 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. */ static atomic_t cpuset_mems_generation = ATOMIC_INIT(1); 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 semaphores below. They can nest. * It is ok to first take manage_sem, then nest callback_sem. 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 semaphores to modify cpusets. If a task * holds manage_sem, then it blocks others wanting that semaphore, * ensuring that it is the only task able to also acquire callback_sem * 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_sem. While it is * performing these checks, various callback routines can briefly * acquire callback_sem to query cpusets. Once it is ready to make * the changes, it takes callback_sem, blocking everyone else. * * Calls to the kernel memory allocator can not be made while holding * callback_sem, as that would risk double tripping on callback_sem * from one of the callbacks into the cpuset code from within * __alloc_pages(). * * If a task is only holding callback_sem, 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_sem or callback_sem can't rely * on the count field not changing. However, if the count goes to * zero, then only attach_task(), which holds both semaphores, 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_sem or callback_sem can safely assume that * if the count is zero, it will stay zero. Similarly, if a task * holds manage_sem or callback_sem on a cpuset with zero count, it * knows that the cpuset won't be removed, as cpuset_rmdir() needs * both of those semaphores. * * A possible optimization to improve parallelism would be to make * callback_sem a R/W semaphore (rwsem), allowing the callback routines * to proceed in parallel, with read access, until the holder of * manage_sem needed to take this rwsem for exclusive write access * and modify some cpusets. * * The cpuset_common_file_write handler for operations that modify * the cpuset hierarchy holds manage_sem across the entire operation, * single threading all such cpuset modifications across the system. * * The cpuset_common_file_read() handlers only hold callback_sem 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 semaphore. 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_sem * 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, pid == 1), 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 semaphores, however there are several performance * critical places that need to reference task->cpuset without the * expense of grabbing a system global semaphore. 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. */ static DECLARE_MUTEX(manage_sem); static DECLARE_MUTEX(callback_sem); /* * 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_blksize = PAGE_CACHE_SIZE; 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_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_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) */ inode->i_nlink++; } else { return -ENOMEM; } root = d_alloc_root(inode); if (!root) { iput(inode); return -ENOMEM; } sb->s_root = root; return 0; } static struct super_block *cpuset_get_sb(struct file_system_type *fs_type, int flags, const char *unused_dev_name, void *data) { return get_sb_single(fs_type, flags, data, cpuset_fill_super); } 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_dentry->d_parent->d_fsdata * - the 'cftype' of the file is file->f_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_sem 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 semaphore, 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_sem, but we still don't, so as to minimize * the time manage_sem 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, 0); 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_sem is dropped. * Call here with manage_sem 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_sem held and the address * of the pathbuf pointer, then dropping manage_sem, 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_sem 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. If none are online, 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_online_map. * * One way or another, we guarantee to return some non-empty subset * of node_online_map. * * Call with callback_sem held. */ static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask) { while (cs && !nodes_intersects(cs->mems_allowed, node_online_map)) cs = cs->parent; if (cs) nodes_and(*pmask, cs->mems_allowed, node_online_map); else *pmask = node_online_map; BUG_ON(!nodes_intersects(*pmask, node_online_map)); } /* * Refresh current tasks mems_allowed and mems_generation from current * tasks cpuset. * * Call without callback_sem or task_lock() held. May be called with * or without manage_sem held. Will acquire task_lock() and might * acquire callback_sem during call. * * The task_lock() is required to dereference current->cpuset safely. * Without it, we could pick up the pointer value of current->cpuset * in one instruction, and then attach_task could give us a different * cpuset, and then the cpuset we had could be removed and freed, * and then on our next instruction, we could dereference a no longer * valid cpuset pointer to get its mems_generation field. * * 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. */ static void refresh_mems(void) { int my_cpusets_mem_gen; task_lock(current); my_cpusets_mem_gen = current->cpuset->mems_generation; task_unlock(current); if (current->cpuset_mems_generation != my_cpusets_mem_gen) { struct cpuset *cs; nodemask_t oldmem = current->mems_allowed; int migrate; down(&callback_sem); task_lock(current); cs = current->cpuset; migrate = is_memory_migrate(cs); guarantee_online_mems(cs, ¤t->mems_allowed); current->cpuset_mems_generation = cs->mems_generation; task_unlock(current); up(&callback_sem); if (!nodes_equal(oldmem, current->mems_allowed)) { numa_policy_rebind(&oldmem, ¤t->mems_allowed); if (migrate) { do_migrate_pages(current->mm, &oldmem, ¤t->mems_allowed, MPOL_MF_MOVE_ALL); } } } } /* * 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_sem. */ 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_sem 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 ((par = cur->parent) == NULL) return 0; /* 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; } /* * For a given cpuset cur, partition the system as follows * a. All cpus in the parent cpuset's cpus_allowed that are not part of any * exclusive child cpusets * b. All cpus in the current cpuset's cpus_allowed that are not part of any * exclusive child cpusets * Build these two partitions by calling partition_sched_domains * * Call with manage_sem held. May nest a call to the * lock_cpu_hotplug()/unlock_cpu_hotplug() pair. */ static void update_cpu_domains(struct cpuset *cur) { struct cpuset *c, *par = cur->parent; cpumask_t pspan, cspan; if (par == NULL || cpus_empty(cur->cpus_allowed)) return; /* * Get all cpus from parent's cpus_allowed not part of exclusive * children */ pspan = par->cpus_allowed; list_for_each_entry(c, &par->children, sibling) { if (is_cpu_exclusive(c)) cpus_andnot(pspan, pspan, c->cpus_allowed); } if (is_removed(cur) || !is_cpu_exclusive(cur)) { cpus_or(pspan, pspan, cur->cpus_allowed); if (cpus_equal(pspan, cur->cpus_allowed)) return; cspan = CPU_MASK_NONE; } else { if (cpus_empty(pspan)) return; cspan = cur->cpus_allowed; /* * Get all cpus from current cpuset's cpus_allowed not part * of exclusive children */ list_for_each_entry(c, &cur->children, sibling) { if (is_cpu_exclusive(c)) cpus_andnot(cspan, cspan, c->cpus_allowed); } } lock_cpu_hotplug(); partition_sched_domains(&pspan, &cspan); unlock_cpu_hotplug(); } /* * Call with manage_sem held. May take callback_sem during call. */ static int update_cpumask(struct cpuset *cs, char *buf) { struct cpuset trialcs; int retval, cpus_unchanged; trialcs = *cs; retval = cpulist_parse(buf, trialcs.cpus_allowed); if (retval < 0) return retval; cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map); if (cpus_empty(trialcs.cpus_allowed)) return -ENOSPC; retval = validate_change(cs, &trialcs); if (retval < 0) return retval; cpus_unchanged = cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed); down(&callback_sem); cs->cpus_allowed = trialcs.cpus_allowed; up(&callback_sem); if (is_cpu_exclusive(cs) && !cpus_unchanged) update_cpu_domains(cs); return 0; } /* * Call with manage_sem held. May take callback_sem during call. */ static int update_nodemask(struct cpuset *cs, char *buf) { struct cpuset trialcs; int retval; trialcs = *cs; retval = nodelist_parse(buf, trialcs.mems_allowed); if (retval < 0) goto done; nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map); if (nodes_empty(trialcs.mems_allowed)) { retval = -ENOSPC; goto done; } retval = validate_change(cs, &trialcs); if (retval < 0) goto done; down(&callback_sem); cs->mems_allowed = trialcs.mems_allowed; atomic_inc(&cpuset_mems_generation); cs->mems_generation = atomic_read(&cpuset_mems_generation); up(&callback_sem); done: return retval; } /* * Call with manage_sem 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: the cpuset to update * buf: the buffer where we read the 0 or 1 * * Call with manage_sem held. */ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, char *buf) { int turning_on; struct cpuset trialcs; int err, cpu_exclusive_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; cpu_exclusive_changed = (is_cpu_exclusive(cs) != is_cpu_exclusive(&trialcs)); down(&callback_sem); if (turning_on) set_bit(bit, &cs->flags); else clear_bit(bit, &cs->flags); up(&callback_sem); if (cpu_exclusive_changed) update_cpu_domains(cs); return 0; } /* * Frequency meter - How fast is some event occuring? * * 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_sem. May take callback_sem 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; 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); } down(&callback_sem); task_lock(tsk); oldcs = tsk->cpuset; if (!oldcs) { task_unlock(tsk); up(&callback_sem); put_task_struct(tsk); return -ESRCH; } atomic_inc(&cs->count); tsk->cpuset = cs; task_unlock(tsk); guarantee_online_cpus(cs, &cpus); set_cpus_allowed(tsk, cpus); from = oldcs->mems_allowed; to = cs->mems_allowed; up(&callback_sem); if (is_memory_migrate(cs)) do_migrate_pages(tsk->mm, &from, &to, MPOL_MF_MOVE_ALL); put_task_struct(tsk); 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_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_dentry->d_parent); struct cftype *cft = __d_cft(file->f_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 * NR_CPUS) 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 */ down(&manage_sem); 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_TASKLIST: retval = attach_task(cs, buffer, &pathbuf); break; default: retval = -EINVAL; goto out2; } if (retval == 0) retval = nbytes; out2: up(&manage_sem); 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_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; down(&callback_sem); mask = cs->cpus_allowed; up(&callback_sem); return cpulist_scnprintf(page, PAGE_SIZE, mask); } static int cpuset_sprintf_memlist(char *page, struct cpuset *cs) { nodemask_t mask; down(&callback_sem); mask = cs->mems_allowed; up(&callback_sem); 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_dentry); struct cpuset *cs = __d_cs(file->f_dentry->d_parent); cpuset_filetype_t type = cft->private; char *page; ssize_t retval = 0; char *s; if (!(page = (char *)__get_free_page(GFP_KERNEL))) 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; 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_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_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_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 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 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) */ inode->i_nlink++; } 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; parent->d_inode->i_nlink++; cs->dentry = dentry; } dput(dentry); return error; } static int cpuset_add_file(struct dentry *dir, const struct cftype *cft) { struct dentry *dentry; int error; down(&dir->d_inode->i_sem); 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); up(&dir->d_inode->i_sem); 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 inline 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) { pidarray[n++] = p->pid; if (unlikely(n == npids)) goto array_full; } } 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 semaphores, and does not take any. */ static int cpuset_tasks_open(struct inode *unused, struct file *file) { struct cpuset *cs = __d_cs(file->f_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; if (*ppos + nbytes > ctr->bufsz) nbytes = ctr->bufsz - *ppos; if (copy_to_user(buf, ctr->buf + *ppos, nbytes)) return -EFAULT; *ppos += nbytes; return nbytes; } 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 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_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 semaphore 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; down(&manage_sem); refresh_mems(); cs->flags = 0; if (notify_on_release(parent)) set_bit(CS_NOTIFY_ON_RELEASE, &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); atomic_inc(&cpuset_mems_generation); cs->mems_generation = atomic_read(&cpuset_mems_generation); fmeter_init(&cs->fmeter); cs->parent = parent; down(&callback_sem); list_add(&cs->sibling, &cs->parent->children); up(&callback_sem); err = cpuset_create_dir(cs, name, mode); if (err < 0) goto err; /* * Release manage_sem before cpuset_populate_dir() because it * will down() this new directory's i_sem and if we race with * another mkdir, we might deadlock. */ up(&manage_sem); err = cpuset_populate_dir(cs->dentry); /* If err < 0, we have a half-filled directory - oh well ;) */ return 0; err: list_del(&cs->sibling); up(&manage_sem); 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_sem 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_sem already */ down(&manage_sem); refresh_mems(); if (atomic_read(&cs->count) > 0) { up(&manage_sem); return -EBUSY; } if (!list_empty(&cs->children)) { up(&manage_sem); return -EBUSY; } parent = cs->parent; down(&callback_sem); set_bit(CS_REMOVED, &cs->flags); if (is_cpu_exclusive(cs)) update_cpu_domains(cs); 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); up(&callback_sem); if (list_empty(&parent->children)) check_for_release(parent, &pathbuf); up(&manage_sem); cpuset_release_agent(pathbuf); 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); atomic_inc(&cpuset_mems_generation); top_cpuset.mems_generation = atomic_read(&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; root->d_inode->i_nlink++; top_cpuset.dentry = root; root->d_inode->i_op = &cpuset_dir_inode_operations; 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; } /** * 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_online_map; } /** * 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_sem semaphore 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_sem * or callback_sem. 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_sem, not callback_sem, because * it is holding that semaphore while calling check_for_release(), * which calls kmalloc(), so can't be called holding callback__sem(). * * We don't need to task_lock() this reference to tsk->cpuset, * because tsk is already marked PF_EXITING, so attach_task() won't * mess with it, or task is a failed fork, never visible to attach_task. **/ void cpuset_exit(struct task_struct *tsk) { struct cpuset *cs; cs = tsk->cpuset; tsk->cpuset = NULL; if (notify_on_release(cs)) { char *pathbuf = NULL; down(&manage_sem); if (atomic_dec_and_test(&cs->count)) check_for_release(cs, &pathbuf); up(&manage_sem); 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(const struct task_struct *tsk) { cpumask_t mask; down(&callback_sem); task_lock((struct task_struct *)tsk); guarantee_online_cpus(tsk->cpuset, &mask); task_unlock((struct task_struct *)tsk); up(&callback_sem); return mask; } void cpuset_init_current_mems_allowed(void) { current->mems_allowed = NODE_MASK_ALL; } /** * cpuset_update_current_mems_allowed - update mems parameters to new values * * If the current tasks cpusets mems_allowed changed behind our backs, * update current->mems_allowed and mems_generation to the new value. * Do not call this routine if in_interrupt(). * * Call without callback_sem or task_lock() held. May be called * with or without manage_sem held. Unless exiting, it will acquire * task_lock(). Also might acquire callback_sem during call to * refresh_mems(). */ void cpuset_update_current_mems_allowed(void) { struct cpuset *cs; int need_to_refresh = 0; task_lock(current); cs = current->cpuset; if (!cs) goto done; if (current->cpuset_mems_generation != cs->mems_generation) need_to_refresh = 1; done: task_unlock(current); if (need_to_refresh) refresh_mems(); } /** * 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 = zl->zones[i]->zone_pgdat->node_id; 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_sem. * 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 - Can we allocate memory on zone z's memory node? * @z: is this zone on an allowed node? * @gfp_mask: memory allocation flags (we use __GFP_HARDWALL) * * If we're in interrupt, 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. * Otherwise, no. * * GFP_USER allocations are marked with the __GFP_HARDWALL bit, * and do not allow allocations outside the current tasks cpuset. * GFP_KERNEL allocations are not so marked, so can escape to the * nearest mem_exclusive ancestor cpuset. * * Scanning up parent cpusets requires callback_sem. 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_sem semaphore. * * The first loop over the zonelist in mm/page_alloc.c:__alloc_pages() * calls here with __GFP_HARDWALL always set in gfp_mask, enforcing * hardwall cpusets - no allocation on a node outside the cpuset is * allowed (unless in interrupt, of course). * * The second loop doesn't even call here for GFP_ATOMIC requests * (if the __alloc_pages() local variable 'wait' is set). That check * and the checks below have the combined affect in the second loop of * the __alloc_pages() routine that: * in_interrupt - any node ok (current task context irrelevant) * GFP_ATOMIC - any node ok * GFP_KERNEL - any node in enclosing mem_exclusive cpuset ok * GFP_USER - only nodes in current tasks mems allowed ok. **/ int cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask) { int node; /* node that zone z is on */ const struct cpuset *cs; /* current cpuset ancestors */ int allowed = 1; /* is allocation in zone z allowed? */ if (in_interrupt()) return 1; node = z->zone_pgdat->node_id; if (node_isset(node, current->mems_allowed)) 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 */ down(&callback_sem); task_lock(current); cs = nearest_exclusive_ancestor(current->cpuset); task_unlock(current); allowed = node_isset(node, cs->mems_allowed); up(&callback_sem); return allowed; } /** * cpuset_excl_nodes_overlap - Do we overlap @p's mem_exclusive ancestors? * @p: pointer to task_struct of some other task. * * Description: Return true if the nearest mem_exclusive ancestor * cpusets of tasks @p and current overlap. Used by oom killer to * determine if task @p's memory usage might impact the memory * available to the current task. * * Acquires callback_sem - not suitable for calling from a fast path. **/ int cpuset_excl_nodes_overlap(const struct task_struct *p) { const struct cpuset *cs1, *cs2; /* my and p's cpuset ancestors */ int overlap = 0; /* do cpusets overlap? */ down(&callback_sem); task_lock(current); if (current->flags & PF_EXITING) { task_unlock(current); goto done; } cs1 = nearest_exclusive_ancestor(current->cpuset); task_unlock(current); task_lock((struct task_struct *)p); if (p->flags & PF_EXITING) { task_unlock((struct task_struct *)p); goto done; } cs2 = nearest_exclusive_ancestor(p->cpuset); task_unlock((struct task_struct *)p); overlap = nodes_intersects(cs1->mems_allowed, cs2->mems_allowed); done: up(&callback_sem); return overlap; } /* * 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//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_sem, keeping attach_task() from changing it * anyway. */ static int proc_cpuset_show(struct seq_file *m, void *v) { struct cpuset *cs; struct task_struct *tsk; char *buf; int retval = 0; buf = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!buf) return -ENOMEM; tsk = m->private; down(&manage_sem); cs = tsk->cpuset; if (!cs) { retval = -EINVAL; goto out; } retval = cpuset_path(cs, buf, PAGE_SIZE); if (retval < 0) goto out; seq_puts(m, buf); seq_putc(m, '\n'); out: up(&manage_sem); kfree(buf); return retval; } static int cpuset_open(struct inode *inode, struct file *file) { struct task_struct *tsk = PROC_I(inode)->task; return single_open(file, proc_cpuset_show, tsk); } 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//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; }