1 files changed, 1564 insertions, 0 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
new file mode 100644
index 000000000000..69792bbe2281
--- /dev/null
+++ b/kernel/cpuset.c
@@ -0,0 +1,1564 @@
+/*
+ *  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 <simon.derr@bull.net>
+ *  2003-10-22 Updates by Stephen Hemminger.
+ *  2004 May-July Rework by Paul Jackson <pj@sgi.com>
+ *
+ *  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/config.h>
+#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/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/sched.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/smp_lock.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 <asm/semaphore.h>
+
+#define CPUSET_SUPER_MAGIC              0x27e0eb
+
+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 */
+
+        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;
+};
+
+/* bits in struct cpuset flags field */
+typedef enum {
+        CS_CPU_EXCLUSIVE,
+        CS_MEM_EXCLUSIVE,
+        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);
+}
+
+/*
+ * 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),
+        .parent = NULL,
+        .dentry = NULL,
+        .mems_generation = 0,
+};
+
+static struct vfsmount *cpuset_mount;
+static struct super_block *cpuset_sb = NULL;
+
+/*
+ * cpuset_sem should be held by anyone who is depending on the children
+ * or sibling lists of any cpuset, or performing non-atomic operations
+ * on the flags or *_allowed values of a cpuset, such as raising the
+ * CS_REMOVED flag bit iff it is not already raised, or reading and
+ * conditionally modifying the *_allowed values.  One kernel global
+ * cpuset semaphore should be sufficient - these things don't change
+ * that much.
+ *
+ * The code that modifies cpusets holds cpuset_sem across the entire
+ * operation, from cpuset_common_file_write() down, single threading
+ * all cpuset modifications (except for counter manipulations from
+ * fork and exit) across the system.  This presumes that cpuset
+ * modifications are rare - better kept simple and safe, even if slow.
+ *
+ * The code that reads cpusets, such as in cpuset_common_file_read()
+ * and below, only holds cpuset_sem across small pieces of code, such
+ * as when reading out possibly multi-word cpumasks and nodemasks, as
+ * the risks are less, and the desire for performance a little greater.
+ * The proc_cpuset_show() routine needs to hold cpuset_sem to insure
+ * that no cs->dentry is NULL, as it walks up the cpuset tree to root.
+ *
+ * The hooks from fork and exit, cpuset_fork() and cpuset_exit(), don't
+ * (usually) grab cpuset_sem.  These are the two most performance
+ * critical pieces of code here.  The exception occurs on exit(),
+ * if the last task using a cpuset exits, and the cpuset was marked
+ * notify_on_release.  In that case, the cpuset_sem is taken, the
+ * path to the released cpuset calculated, and 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 no need
+ * for any special hack to ensure that top_cpuset cannot be deleted.
+ */
+
+static DECLARE_MUTEX(cpuset_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 qstr qstr;
+        struct dentry *d;
+
+        qstr.name = name;
+        qstr.len = strlen(name);
+        qstr.hash = full_name_hash(name, qstr.len);
+        d = lookup_hash(&qstr, parent);
+        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 cpuset_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.
+ *
+ * Note final arg to call_usermodehelper() is 0 - that means
+ * don't wait.  Since we are holding the global cpuset_sem here,
+ * and we are asking another thread (started from keventd) to rmdir a
+ * cpuset, we can't wait - or we'd deadlock with the removing thread
+ * on cpuset_sem.
+ */
+
+static int cpuset_release_agent(char *cpuset_str)
+{
+        char *argv[3], *envp[3];
+        int i;
+
+        i = 0;
+        argv[i++] = "/sbin/cpuset_release_agent";
+        argv[i++] = cpuset_str;
+        argv[i] = NULL;
+
+        i = 0;
+        /* minimal command environment */
+        envp[i++] = "HOME=/";
+        envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+        envp[i] = NULL;
+
+        return call_usermodehelper(argv[0], argv, envp, 0);
+}
+
+/*
+ * 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, send notice to user land.
+ */
+
+static void check_for_release(struct cpuset *cs)
+{
+        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)
+                        goto out;
+                cpuset_release_agent(buf);
+out:
+                kfree(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 cpuset_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 cpuset_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 with cpuset_sem held.
+ *
+ * Be sure to call refresh_mems() on any cpuset operation which
+ * (1) holds cpuset_sem, and (2) might possibly alloc memory.
+ * Call after obtaining cpuset_sem lock, before any possible
+ * allocation.  Otherwise one risks trying to allocate memory
+ * while the task cpuset_mems_generation is not the same as
+ * the mems_generation in its cpuset, which would deadlock on
+ * cpuset_sem in cpuset_update_current_mems_allowed().
+ *
+ * Since we hold cpuset_sem, once refresh_mems() is called, the
+ * test (current->cpuset_mems_generation != cs->mems_generation)
+ * in cpuset_update_current_mems_allowed() will remain false,
+ * until we drop cpuset_sem.  Anyone else who would change our
+ * cpusets mems_generation needs to lock cpuset_sem first.
+ */
+
+static void refresh_mems(void)
+{
+        struct cpuset *cs = current->cpuset;
+
+        if (current->cpuset_mems_generation != cs->mems_generation) {
+                guarantee_online_mems(cs, &current->mems_allowed);
+                current->cpuset_mems_generation = cs->mems_generation;
+        }
+}
+
+/*
+ * 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.
+ */
+
+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
+ * cpuset_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;
+}
+
+static int update_cpumask(struct cpuset *cs, char *buf)
+{
+        struct cpuset trialcs;
+        int retval;
+
+        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)
+                cs->cpus_allowed = trialcs.cpus_allowed;
+        return retval;
+}
+
+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)
+                return retval;
+        nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map);
+        if (nodes_empty(trialcs.mems_allowed))
+                return -ENOSPC;
+        retval = validate_change(cs, &trialcs);
+        if (retval == 0) {
+                cs->mems_allowed = trialcs.mems_allowed;
+                atomic_inc(&cpuset_mems_generation);
+                cs->mems_generation = atomic_read(&cpuset_mems_generation);
+        }
+        return retval;
+}
+
+/*
+ * 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:  the cpuset to update
+ * buf: the buffer where we read the 0 or 1
+ */
+
+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) {
+                if (turning_on)
+                        set_bit(bit, &cs->flags);
+                else
+                        clear_bit(bit, &cs->flags);
+        }
+        return err;
+}
+
+static int attach_task(struct cpuset *cs, char *buf)
+{
+        pid_t pid;
+        struct task_struct *tsk;
+        struct cpuset *oldcs;
+        cpumask_t cpus;
+
+        if (sscanf(buf, "%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) {
+                        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);
+        }
+
+        task_lock(tsk);
+        oldcs = tsk->cpuset;
+        if (!oldcs) {
+                task_unlock(tsk);
+                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);
+
+        put_task_struct(tsk);
+        if (atomic_dec_and_test(&oldcs->count))
+                check_for_release(oldcs);
+        return 0;
+}
+
+/* The various types of files and directories in a cpuset file system */
+
+typedef enum {
+        FILE_ROOT,
+        FILE_DIR,
+        FILE_CPULIST,
+        FILE_MEMLIST,
+        FILE_CPU_EXCLUSIVE,
+        FILE_MEM_EXCLUSIVE,
+        FILE_NOTIFY_ON_RELEASE,
+        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;
+        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(&cpuset_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_TASKLIST:
+                retval = attach_task(cs, buffer);
+                break;
+        default:
+                retval = -EINVAL;
+                goto out2;
+        }
+
+        if (retval == 0)
+                retval = nbytes;
+out2:
+        up(&cpuset_sem);
+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(&cpuset_sem);
+        mask = cs->cpus_allowed;
+        up(&cpuset_sem);
+
+        return cpulist_scnprintf(page, PAGE_SIZE, mask);
+}
+
+static int cpuset_sprintf_memlist(char *page, struct cpuset *cs)
+{
+        nodemask_t mask;
+
+        down(&cpuset_sem);
+        mask = cs->mems_allowed;
+        up(&cpuset_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;
+        char *start;
+        size_t n;
+
+        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;
+        default:
+                retval = -EINVAL;
+                goto out;
+        }
+        *s++ = '\n';
+        *s = '\0';
+
+        start = page + *ppos;
+        n = s - start;
+        retval = n - copy_to_user(buf, start, min(n, nbytes));
+        *ppos += retval;
+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;
+}
+
+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,
+};
+
+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.
+ */
+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;
+}
+
+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 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_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(&cpuset_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);
+
+        cs->parent = parent;
+
+        list_add(&cs->sibling, &cs->parent->children);
+
+        err = cpuset_create_dir(cs, name, mode);
+        if (err < 0)
+                goto err;
+
+        /*
+         * Release cpuset_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(&cpuset_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(&cpuset_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;
+
+        /* the vfs holds both inode->i_sem already */
+
+        down(&cpuset_sem);
+        refresh_mems();
+        if (atomic_read(&cs->count) > 0) {
+                up(&cpuset_sem);
+                return -EBUSY;
+        }
+        if (!list_empty(&cs->children)) {
+                up(&cpuset_sem);
+                return -EBUSY;
+        }
+        spin_lock(&cs->dentry->d_lock);
+        parent = cs->parent;
+        set_bit(CS_REMOVED, &cs->flags);
+        list_del(&cs->sibling); /* delete my sibling from parent->children */
+        if (list_empty(&parent->children))
+                check_for_release(parent);
+        d = dget(cs->dentry);
+        cs->dentry = NULL;
+        spin_unlock(&d->d_lock);
+        cpuset_d_remove_dir(d);
+        dput(d);
+        up(&cpuset_sem);
+        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;
+
+        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);
+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.
+ * @p: pointer to task_struct of forking parent process.
+ *
+ * Description: By default, on fork, a task inherits its
+ * parents cpuset.  The pointer to the shared cpuset is
+ * automatically copied in fork.c by dup_task_struct().
+ * This cpuset_fork() routine need only increment the usage
+ * counter in that cpuset.
+ **/
+
+void cpuset_fork(struct task_struct *tsk)
+{
+        atomic_inc(&tsk->cpuset->count);
+}
+
+/**
+ * cpuset_exit - detach cpuset from exiting task
+ * @tsk: pointer to task_struct of exiting process
+ *
+ * Description: Detach cpuset from @tsk and release it.
+ *
+ **/
+
+void cpuset_exit(struct task_struct *tsk)
+{
+        struct cpuset *cs;
+
+        task_lock(tsk);
+        cs = tsk->cpuset;
+        tsk->cpuset = NULL;
+        task_unlock(tsk);
+
+        if (atomic_dec_and_test(&cs->count)) {
+                down(&cpuset_sem);
+                check_for_release(cs);
+                up(&cpuset_sem);
+        }
+}
+
+/**
+ * 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.
+ **/
+
+const cpumask_t cpuset_cpus_allowed(const struct task_struct *tsk)
+{
+        cpumask_t mask;
+
+        down(&cpuset_sem);
+        task_lock((struct task_struct *)tsk);
+        guarantee_online_cpus(tsk->cpuset, &mask);
+        task_unlock((struct task_struct *)tsk);
+        up(&cpuset_sem);
+
+        return mask;
+}
+
+void cpuset_init_current_mems_allowed(void)
+{
+        current->mems_allowed = NODE_MASK_ALL;
+}
+
+/*
+ * 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().
+ */
+
+void cpuset_update_current_mems_allowed(void)
+{
+        struct cpuset *cs = current->cpuset;
+
+        if (!cs)
+                return;         /* task is exiting */
+        if (current->cpuset_mems_generation != cs->mems_generation) {
+                down(&cpuset_sem);
+                refresh_mems();
+                up(&cpuset_sem);
+        }
+}
+
+void cpuset_restrict_to_mems_allowed(unsigned long *nodes)
+{
+        bitmap_and(nodes, nodes, nodes_addr(current->mems_allowed),
+                                                        MAX_NUMNODES);
+}
+
+/*
+ * 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;
+}
+
+/*
+ * Is 'current' valid, and is zone z allowed in current->mems_allowed?
+ */
+int cpuset_zone_allowed(struct zone *z)
+{
+        return in_interrupt() ||
+                node_isset(z->zone_pgdat->node_id, current->mems_allowed);
+}
+
+/*
+ * proc_cpuset_show()
+ *  - Print tasks cpuset path into seq_file.
+ *  - Used for /proc/<pid>/cpuset.
+ */
+
+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(&cpuset_sem);
+        task_lock(tsk);
+        cs = tsk->cpuset;
+        task_unlock(tsk);
+        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(&cpuset_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/<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;
+}