Merge commit 'v2.6.28-rc2' into x86/pci-ioapic-boot-irq-quirks

1 files changed, 380 insertions, 322 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 459d601947a8..3e00526f52ec 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -14,6 +14,8 @@
  *  2003-10-22 Updates by Stephen Hemminger.
  *  2004 May-July Rework by Paul Jackson.
  *  2006 Rework by Paul Menage to use generic cgroups
+ *  2008 Rework of the scheduler domains and CPU hotplug handling
+ *       by Max Krasnyansky
  *
  *  This file is subject to the terms and conditions of the GNU General Public
  *  License.  See the file COPYING in the main directory of the Linux
@@ -54,7 +56,6 @@
 #include <asm/uaccess.h>
 #include <asm/atomic.h>
 #include <linux/mutex.h>
-#include <linux/kfifo.h>
 #include <linux/workqueue.h>
 #include <linux/cgroup.h>
 
@@ -227,10 +228,6 @@ static struct cpuset top_cpuset = {
  * The task_struct fields mems_allowed and mems_generation may only
  * be accessed in the context of that task, so require no locks.
  *
- * The cpuset_common_file_write handler for operations that modify
- * the cpuset hierarchy holds cgroup_mutex across the entire operation,
- * single threading all such cpuset modifications across the system.
- *
  * The cpuset_common_file_read() handlers only hold callback_mutex across
  * small pieces of code, such as when reading out possibly multi-word
  * cpumasks and nodemasks.
@@ -241,9 +238,11 @@ static struct cpuset top_cpuset = {
 
 static DEFINE_MUTEX(callback_mutex);
 
-/* This is ugly, but preserves the userspace API for existing cpuset
+/*
+ * This is ugly, but preserves the userspace API for existing cpuset
  * users. If someone tries to mount the "cpuset" filesystem, we
- * silently switch it to mount "cgroup" instead */
+ * silently switch it to mount "cgroup" instead
+ */
 static int cpuset_get_sb(struct file_system_type *fs_type,
                          int flags, const char *unused_dev_name,
                          void *data, struct vfsmount *mnt)
@@ -369,7 +368,7 @@ void cpuset_update_task_memory_state(void)
                 my_cpusets_mem_gen = top_cpuset.mems_generation;
         } else {
                 rcu_read_lock();
-                my_cpusets_mem_gen = task_cs(current)->mems_generation;
+                my_cpusets_mem_gen = task_cs(tsk)->mems_generation;
                 rcu_read_unlock();
         }
 
@@ -478,10 +477,9 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
 }
 
 /*
- * Helper routine for rebuild_sched_domains().
+ * Helper routine for generate_sched_domains().
  * Do cpusets a, b have overlapping cpus_allowed masks?
  */
-
 static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
 {
         return cpus_intersects(a->cpus_allowed, b->cpus_allowed);
@@ -490,29 +488,48 @@ static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
 static void
 update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
 {
-        if (!dattr)
-                return;
         if (dattr->relax_domain_level < c->relax_domain_level)
                 dattr->relax_domain_level = c->relax_domain_level;
         return;
 }
 
+static void
+update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c)
+{
+        LIST_HEAD(q);
+
+        list_add(&c->stack_list, &q);
+        while (!list_empty(&q)) {
+                struct cpuset *cp;
+                struct cgroup *cont;
+                struct cpuset *child;
+
+                cp = list_first_entry(&q, struct cpuset, stack_list);
+                list_del(q.next);
+
+                if (cpus_empty(cp->cpus_allowed))
+                        continue;
+
+                if (is_sched_load_balance(cp))
+                        update_domain_attr(dattr, cp);
+
+                list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
+                        child = cgroup_cs(cont);
+                        list_add_tail(&child->stack_list, &q);
+                }
+        }
+}
+
 /*
- * rebuild_sched_domains()
+ * generate_sched_domains()
  *
- * If the flag 'sched_load_balance' of any cpuset with non-empty
- * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
- * which has that flag enabled, or if any cpuset with a non-empty
- * 'cpus' is removed, then call this routine to rebuild the
- * scheduler's dynamic sched domains.
- *
- * This routine builds a partial partition of the systems CPUs
- * (the set of non-overlappping cpumask_t's in the array 'part'
- * below), and passes that partial partition to the kernel/sched.c
- * partition_sched_domains() routine, which will rebuild the
- * schedulers load balancing domains (sched domains) as specified
- * by that partial partition.  A 'partial partition' is a set of
- * non-overlapping subsets whose union is a subset of that set.
+ * This function builds a partial partition of the systems CPUs
+ * A 'partial partition' is a set of non-overlapping subsets whose
+ * union is a subset of that set.
+ * The output of this function needs to be passed to kernel/sched.c
+ * partition_sched_domains() routine, which will rebuild the scheduler's
+ * load balancing domains (sched domains) as specified by that partial
+ * partition.
  *
  * See "What is sched_load_balance" in Documentation/cpusets.txt
  * for a background explanation of this.
@@ -522,16 +539,10 @@ update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
  * domains when operating in the severe memory shortage situations
  * that could cause allocation failures below.
  *
- * Call with cgroup_mutex held.  May take callback_mutex during
- * call due to the kfifo_alloc() and kmalloc() calls.  May nest
- * a call to the get_online_cpus()/put_online_cpus() pair.
- * Must not be called holding callback_mutex, because we must not
- * call get_online_cpus() while holding callback_mutex.  Elsewhere
- * the kernel nests callback_mutex inside get_online_cpus() calls.
- * So the reverse nesting would risk an ABBA deadlock.
+ * Must be called with cgroup_lock held.
  *
  * The three key local variables below are:
- *    q  - a kfifo queue of cpuset pointers, used to implement a
+ *    q  - a linked-list queue of cpuset pointers, used to implement a
  *         top-down scan of all cpusets.  This scan loads a pointer
  *         to each cpuset marked is_sched_load_balance into the
  *         array 'csa'.  For our purposes, rebuilding the schedulers
@@ -563,10 +574,10 @@ update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
  *      element of the partition (one sched domain) to be passed to
  *      partition_sched_domains().
  */
-
-static void rebuild_sched_domains(void)
+static int generate_sched_domains(cpumask_t **domains,
+                        struct sched_domain_attr **attributes)
 {
-        struct kfifo *q;        /* queue of cpusets to be scanned */
+        LIST_HEAD(q);           /* queue of cpusets to be scanned */
         struct cpuset *cp;      /* scans q */
         struct cpuset **csa;    /* array of all cpuset ptrs */
         int csn;                /* how many cpuset ptrs in csa so far */
@@ -576,44 +587,58 @@ static void rebuild_sched_domains(void)
         int ndoms;              /* number of sched domains in result */
         int nslot;              /* next empty doms[] cpumask_t slot */
 
-        q = NULL;
-        csa = NULL;
+        ndoms = 0;
         doms = NULL;
         dattr = NULL;
+        csa = NULL;
 
         /* Special case for the 99% of systems with one, full, sched domain */
         if (is_sched_load_balance(&top_cpuset)) {
-                ndoms = 1;
                 doms = kmalloc(sizeof(cpumask_t), GFP_KERNEL);
                 if (!doms)
-                        goto rebuild;
+                        goto done;
+
                 dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
                 if (dattr) {
                         *dattr = SD_ATTR_INIT;
-                        update_domain_attr(dattr, &top_cpuset);
+                        update_domain_attr_tree(dattr, &top_cpuset);
                 }
                 *doms = top_cpuset.cpus_allowed;
-                goto rebuild;
-        }
 
-        q = kfifo_alloc(number_of_cpusets * sizeof(cp), GFP_KERNEL, NULL);
-        if (IS_ERR(q))
+                ndoms = 1;
                 goto done;
+        }
+
         csa = kmalloc(number_of_cpusets * sizeof(cp), GFP_KERNEL);
         if (!csa)
                 goto done;
         csn = 0;
 
-        cp = &top_cpuset;
-        __kfifo_put(q, (void *)&cp, sizeof(cp));
-        while (__kfifo_get(q, (void *)&cp, sizeof(cp))) {
+        list_add(&top_cpuset.stack_list, &q);
+        while (!list_empty(&q)) {
                 struct cgroup *cont;
                 struct cpuset *child;   /* scans child cpusets of cp */
-                if (is_sched_load_balance(cp))
+
+                cp = list_first_entry(&q, struct cpuset, stack_list);
+                list_del(q.next);
+
+                if (cpus_empty(cp->cpus_allowed))
+                        continue;
+
+                /*
+                 * All child cpusets contain a subset of the parent's cpus, so
+                 * just skip them, and then we call update_domain_attr_tree()
+                 * to calc relax_domain_level of the corresponding sched
+                 * domain.
+                 */
+                if (is_sched_load_balance(cp)) {
                         csa[csn++] = cp;
+                        continue;
+                }
+
                 list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
                         child = cgroup_cs(cont);
-                        __kfifo_put(q, (void *)&child, sizeof(cp));
+                        list_add_tail(&child->stack_list, &q);
                 }
         }
 
@@ -644,91 +669,141 @@ restart:
                 }
         }
 
-        /* Convert <csn, csa> to <ndoms, doms> */
+        /*
+         * Now we know how many domains to create.
+         * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
+         */
         doms = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL);
-        if (!doms)
-                goto rebuild;
+        if (!doms) {
+                ndoms = 0;
+                goto done;
+        }
+
+        /*
+         * The rest of the code, including the scheduler, can deal with
+         * dattr==NULL case. No need to abort if alloc fails.
+         */
         dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
 
         for (nslot = 0, i = 0; i < csn; i++) {
                 struct cpuset *a = csa[i];
+                cpumask_t *dp;
                 int apn = a->pn;
 
-                if (apn >= 0) {
-                        cpumask_t *dp = doms + nslot;
-
-                        if (nslot == ndoms) {
-                                static int warnings = 10;
-                                if (warnings) {
-                                        printk(KERN_WARNING
-                                         "rebuild_sched_domains confused:"
-                                          " nslot %d, ndoms %d, csn %d, i %d,"
-                                          " apn %d\n",
-                                          nslot, ndoms, csn, i, apn);
-                                        warnings--;
-                                }
-                                continue;
+                if (apn < 0) {
+                        /* Skip completed partitions */
+                        continue;
+                }
+
+                dp = doms + nslot;
+
+                if (nslot == ndoms) {
+                        static int warnings = 10;
+                        if (warnings) {
+                                printk(KERN_WARNING
+                                 "rebuild_sched_domains confused:"
+                                  " nslot %d, ndoms %d, csn %d, i %d,"
+                                  " apn %d\n",
+                                  nslot, ndoms, csn, i, apn);
+                                warnings--;
                         }
+                        continue;
+                }
 
-                        cpus_clear(*dp);
-                        if (dattr)
-                                *(dattr + nslot) = SD_ATTR_INIT;
-                        for (j = i; j < csn; j++) {
-                                struct cpuset *b = csa[j];
+                cpus_clear(*dp);
+                if (dattr)
+                        *(dattr + nslot) = SD_ATTR_INIT;
+                for (j = i; j < csn; j++) {
+                        struct cpuset *b = csa[j];
 
-                                if (apn == b->pn) {
-                                        cpus_or(*dp, *dp, b->cpus_allowed);
-                                        b->pn = -1;
-                                        update_domain_attr(dattr, b);
-                                }
+                        if (apn == b->pn) {
+                                cpus_or(*dp, *dp, b->cpus_allowed);
+                                if (dattr)
+                                        update_domain_attr_tree(dattr + nslot, b);
+
+                                /* Done with this partition */
+                                b->pn = -1;
                         }
-                        nslot++;
                 }
+                nslot++;
         }
         BUG_ON(nslot != ndoms);
 
-rebuild:
-        /* Have scheduler rebuild sched domains */
-        get_online_cpus();
-        partition_sched_domains(ndoms, doms, dattr);
-        put_online_cpus();
-
 done:
-        if (q && !IS_ERR(q))
-                kfifo_free(q);
         kfree(csa);
-        /* Don't kfree(doms) -- partition_sched_domains() does that. */
-        /* Don't kfree(dattr) -- partition_sched_domains() does that. */
+
+        *domains    = doms;
+        *attributes = dattr;
+        return ndoms;
 }
 
-static inline int started_after_time(struct task_struct *t1,
-                                     struct timespec *time,
-                                     struct task_struct *t2)
+/*
+ * Rebuild scheduler domains.
+ *
+ * Call with neither cgroup_mutex held nor within get_online_cpus().
+ * Takes both cgroup_mutex and get_online_cpus().
+ *
+ * Cannot be directly called from cpuset code handling changes
+ * to the cpuset pseudo-filesystem, because it cannot be called
+ * from code that already holds cgroup_mutex.
+ */
+static void do_rebuild_sched_domains(struct work_struct *unused)
 {
-        int start_diff = timespec_compare(&t1->start_time, time);
-        if (start_diff > 0) {
-                return 1;
-        } else if (start_diff < 0) {
-                return 0;
-        } else {
-                /*
-                 * Arbitrarily, if two processes started at the same
-                 * time, we'll say that the lower pointer value
-                 * started first. Note that t2 may have exited by now
-                 * so this may not be a valid pointer any longer, but
-                 * that's fine - it still serves to distinguish
-                 * between two tasks started (effectively)
-                 * simultaneously.
-                 */
-                return t1 > t2;
-        }
+        struct sched_domain_attr *attr;
+        cpumask_t *doms;
+        int ndoms;
+
+        get_online_cpus();
+
+        /* Generate domain masks and attrs */
+        cgroup_lock();
+        ndoms = generate_sched_domains(&doms, &attr);
+        cgroup_unlock();
+
+        /* Have scheduler rebuild the domains */
+        partition_sched_domains(ndoms, doms, attr);
+
+        put_online_cpus();
+}
+
+static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains);
+
+/*
+ * Rebuild scheduler domains, asynchronously via workqueue.
+ *
+ * If the flag 'sched_load_balance' of any cpuset with non-empty
+ * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
+ * which has that flag enabled, or if any cpuset with a non-empty
+ * 'cpus' is removed, then call this routine to rebuild the
+ * scheduler's dynamic sched domains.
+ *
+ * The rebuild_sched_domains() and partition_sched_domains()
+ * routines must nest cgroup_lock() inside get_online_cpus(),
+ * but such cpuset changes as these must nest that locking the
+ * other way, holding cgroup_lock() for much of the code.
+ *
+ * So in order to avoid an ABBA deadlock, the cpuset code handling
+ * these user changes delegates the actual sched domain rebuilding
+ * to a separate workqueue thread, which ends up processing the
+ * above do_rebuild_sched_domains() function.
+ */
+static void async_rebuild_sched_domains(void)
+{
+        schedule_work(&rebuild_sched_domains_work);
 }
 
-static inline int started_after(void *p1, void *p2)
+/*
+ * Accomplishes the same scheduler domain rebuild as the above
+ * async_rebuild_sched_domains(), however it directly calls the
+ * rebuild routine synchronously rather than calling it via an
+ * asynchronous work thread.
+ *
+ * This can only be called from code that is not holding
+ * cgroup_mutex (not nested in a cgroup_lock() call.)
+ */
+void rebuild_sched_domains(void)
 {
-        struct task_struct *t1 = p1;
-        struct task_struct *t2 = p2;
-        return started_after_time(t1, &t2->start_time, t2);
+        do_rebuild_sched_domains(NULL);
 }
 
 /**
@@ -766,15 +841,38 @@ static void cpuset_change_cpumask(struct task_struct *tsk,
 }
 
 /**
+ * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
+ * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
+ * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
+ *
+ * Called with cgroup_mutex held
+ *
+ * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
+ * calling callback functions for each.
+ *
+ * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
+ * if @heap != NULL.
+ */
+static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
+{
+        struct cgroup_scanner scan;
+
+        scan.cg = cs->css.cgroup;
+        scan.test_task = cpuset_test_cpumask;
+        scan.process_task = cpuset_change_cpumask;
+        scan.heap = heap;
+        cgroup_scan_tasks(&scan);
+}
+
+/**
  * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
  * @cs: the cpuset to consider
  * @buf: buffer of cpu numbers written to this cpuset
  */
-static int update_cpumask(struct cpuset *cs, char *buf)
+static int update_cpumask(struct cpuset *cs, const char *buf)
 {
-        struct cpuset trialcs;
-        struct cgroup_scanner scan;
         struct ptr_heap heap;
+        struct cpuset trialcs;
         int retval;
         int is_load_balanced;
 
@@ -790,7 +888,6 @@ static int update_cpumask(struct cpuset *cs, char *buf)
          * that parsing.  The validate_change() call ensures that cpusets
          * with tasks have cpus.
          */
-        buf = strstrip(buf);
         if (!*buf) {
                 cpus_clear(trialcs.cpus_allowed);
         } else {
@@ -809,7 +906,7 @@ static int update_cpumask(struct cpuset *cs, char *buf)
         if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed))
                 return 0;
 
-        retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, &started_after);
+        retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
         if (retval)
                 return retval;
 
@@ -823,15 +920,12 @@ static int update_cpumask(struct cpuset *cs, char *buf)
          * Scan tasks in the cpuset, and update the cpumasks of any
          * that need an update.
          */
-        scan.cg = cs->css.cgroup;
-        scan.test_task = cpuset_test_cpumask;
-        scan.process_task = cpuset_change_cpumask;
-        scan.heap = &heap;
-        cgroup_scan_tasks(&scan);
+        update_tasks_cpumask(cs, &heap);
+
         heap_free(&heap);
 
         if (is_load_balanced)
-                rebuild_sched_domains();
+                async_rebuild_sched_domains();
         return 0;
 }
 
@@ -884,74 +978,25 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
         mutex_unlock(&callback_mutex);
 }
 
-/*
- * Handle user request to change the 'mems' memory placement
- * of a cpuset.  Needs to validate the request, update the
- * cpusets mems_allowed and mems_generation, and for each
- * task in the cpuset, rebind any vma mempolicies and if
- * the cpuset is marked 'memory_migrate', migrate the tasks
- * pages to the new memory.
- *
- * Call with cgroup_mutex held.  May take callback_mutex during call.
- * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
- * lock each such tasks mm->mmap_sem, scan its vma's and rebind
- * their mempolicies to the cpusets new mems_allowed.
- */
-
 static void *cpuset_being_rebound;
 
-static int update_nodemask(struct cpuset *cs, char *buf)
+/**
+ * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
+ * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
+ * @oldmem: old mems_allowed of cpuset cs
+ *
+ * Called with cgroup_mutex held
+ * Return 0 if successful, -errno if not.
+ */
+static int update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem)
 {
-        struct cpuset trialcs;
-        nodemask_t oldmem;
         struct task_struct *p;
         struct mm_struct **mmarray;
         int i, n, ntasks;
         int migrate;
         int fudge;
-        int retval;
         struct cgroup_iter it;
-
-        /*
-         * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
-         * it's read-only
-         */
-        if (cs == &top_cpuset)
-                return -EACCES;
-
-        trialcs = *cs;
-
-        /*
-         * An empty mems_allowed is ok iff there are no tasks in the cpuset.
-         * Since nodelist_parse() fails on an empty mask, we special case
-         * that parsing.  The validate_change() call ensures that cpusets
-         * with tasks have memory.
-         */
-        buf = strstrip(buf);
-        if (!*buf) {
-                nodes_clear(trialcs.mems_allowed);
-        } else {
-                retval = nodelist_parse(buf, trialcs.mems_allowed);
-                if (retval < 0)
-                        goto done;
-
-                if (!nodes_subset(trialcs.mems_allowed,
-                                node_states[N_HIGH_MEMORY]))
-                        return -EINVAL;
-        }
-        oldmem = cs->mems_allowed;
-        if (nodes_equal(oldmem, trialcs.mems_allowed)) {
-                retval = 0;             /* Too easy - nothing to do */
-                goto done;
-        }
-        retval = validate_change(cs, &trialcs);
-        if (retval < 0)
-                goto done;
-
-        mutex_lock(&callback_mutex);
-        cs->mems_allowed = trialcs.mems_allowed;
-        cs->mems_generation = cpuset_mems_generation++;
-        mutex_unlock(&callback_mutex);
+        int retval;
 
         cpuset_being_rebound = cs;              /* causes mpol_dup() rebind */
 
@@ -1018,7 +1063,7 @@ static int update_nodemask(struct cpuset *cs, char *buf)
 
                 mpol_rebind_mm(mm, &cs->mems_allowed);
                 if (migrate)
-                        cpuset_migrate_mm(mm, &oldmem, &cs->mems_allowed);
+                        cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
                 mmput(mm);
         }
 
@@ -1030,6 +1075,70 @@ done:
         return retval;
 }
 
+/*
+ * Handle user request to change the 'mems' memory placement
+ * of a cpuset.  Needs to validate the request, update the
+ * cpusets mems_allowed and mems_generation, and for each
+ * task in the cpuset, rebind any vma mempolicies and if
+ * the cpuset is marked 'memory_migrate', migrate the tasks
+ * pages to the new memory.
+ *
+ * Call with cgroup_mutex held.  May take callback_mutex during call.
+ * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
+ * lock each such tasks mm->mmap_sem, scan its vma's and rebind
+ * their mempolicies to the cpusets new mems_allowed.
+ */
+static int update_nodemask(struct cpuset *cs, const char *buf)
+{
+        struct cpuset trialcs;
+        nodemask_t oldmem;
+        int retval;
+
+        /*
+         * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
+         * it's read-only
+         */
+        if (cs == &top_cpuset)
+                return -EACCES;
+
+        trialcs = *cs;
+
+        /*
+         * An empty mems_allowed is ok iff there are no tasks in the cpuset.
+         * Since nodelist_parse() fails on an empty mask, we special case
+         * that parsing.  The validate_change() call ensures that cpusets
+         * with tasks have memory.
+         */
+        if (!*buf) {
+                nodes_clear(trialcs.mems_allowed);
+        } else {
+                retval = nodelist_parse(buf, trialcs.mems_allowed);
+                if (retval < 0)
+                        goto done;
+
+                if (!nodes_subset(trialcs.mems_allowed,
+                                node_states[N_HIGH_MEMORY]))
+                        return -EINVAL;
+        }
+        oldmem = cs->mems_allowed;
+        if (nodes_equal(oldmem, trialcs.mems_allowed)) {
+                retval = 0;             /* Too easy - nothing to do */
+                goto done;
+        }
+        retval = validate_change(cs, &trialcs);
+        if (retval < 0)
+                goto done;
+
+        mutex_lock(&callback_mutex);
+        cs->mems_allowed = trialcs.mems_allowed;
+        cs->mems_generation = cpuset_mems_generation++;
+        mutex_unlock(&callback_mutex);
+
+        retval = update_tasks_nodemask(cs, &oldmem);
+done:
+        return retval;
+}
+
 int current_cpuset_is_being_rebound(void)
 {
         return task_cs(current) == cpuset_being_rebound;
@@ -1042,7 +1151,8 @@ static int update_relax_domain_level(struct cpuset *cs, s64 val)
 
         if (val != cs->relax_domain_level) {
                 cs->relax_domain_level = val;
-                rebuild_sched_domains();
+                if (!cpus_empty(cs->cpus_allowed) && is_sched_load_balance(cs))
+                        async_rebuild_sched_domains();
         }
 
         return 0;
@@ -1062,7 +1172,7 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
 {
         struct cpuset trialcs;
         int err;
-        int cpus_nonempty, balance_flag_changed;
+        int balance_flag_changed;
 
         trialcs = *cs;
         if (turning_on)
@@ -1074,7 +1184,6 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
         if (err < 0)
                 return err;
 
-        cpus_nonempty = !cpus_empty(trialcs.cpus_allowed);
         balance_flag_changed = (is_sched_load_balance(cs) !=
                                         is_sched_load_balance(&trialcs));
 
@@ -1082,8 +1191,8 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
         cs->flags = trialcs.flags;
         mutex_unlock(&callback_mutex);
 
-        if (cpus_nonempty && balance_flag_changed)
-                rebuild_sched_domains();
+        if (!cpus_empty(trialcs.cpus_allowed) && balance_flag_changed)
+                async_rebuild_sched_domains();
 
         return 0;
 }
@@ -1254,72 +1363,14 @@ typedef enum {
         FILE_SPREAD_SLAB,
 } cpuset_filetype_t;
 
-static ssize_t cpuset_common_file_write(struct cgroup *cont,
-                                        struct cftype *cft,
-                                        struct file *file,
-                                        const char __user *userbuf,
-                                        size_t nbytes, loff_t *unused_ppos)
-{
-        struct cpuset *cs = cgroup_cs(cont);
-        cpuset_filetype_t type = cft->private;
-        char *buffer;
-        int retval = 0;
-
-        /* Crude upper limit on largest legitimate cpulist user might write. */
-        if (nbytes > 100U + 6 * max(NR_CPUS, MAX_NUMNODES))
-                return -E2BIG;
-
-        /* +1 for nul-terminator */
-        buffer = kmalloc(nbytes + 1, GFP_KERNEL);
-        if (!buffer)
-                return -ENOMEM;
-
-        if (copy_from_user(buffer, userbuf, nbytes)) {
-                retval = -EFAULT;
-                goto out1;
-        }
-        buffer[nbytes] = 0;     /* nul-terminate */
-
-        cgroup_lock();
-
-        if (cgroup_is_removed(cont)) {
-                retval = -ENODEV;
-                goto out2;
-        }
-
-        switch (type) {
-        case FILE_CPULIST:
-                retval = update_cpumask(cs, buffer);
-                break;
-        case FILE_MEMLIST:
-                retval = update_nodemask(cs, buffer);
-                break;
-        default:
-                retval = -EINVAL;
-                goto out2;
-        }
-
-        if (retval == 0)
-                retval = nbytes;
-out2:
-        cgroup_unlock();
-out1:
-        kfree(buffer);
-        return retval;
-}
-
 static int cpuset_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
 {
         int retval = 0;
         struct cpuset *cs = cgroup_cs(cgrp);
         cpuset_filetype_t type = cft->private;
 
-        cgroup_lock();
-
-        if (cgroup_is_removed(cgrp)) {
-                cgroup_unlock();
+        if (!cgroup_lock_live_group(cgrp))
                 return -ENODEV;
-        }
 
         switch (type) {
         case FILE_CPU_EXCLUSIVE:
@@ -1365,12 +1416,9 @@ static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val)
         struct cpuset *cs = cgroup_cs(cgrp);
         cpuset_filetype_t type = cft->private;
 
-        cgroup_lock();
-
-        if (cgroup_is_removed(cgrp)) {
-                cgroup_unlock();
+        if (!cgroup_lock_live_group(cgrp))
                 return -ENODEV;
-        }
+
         switch (type) {
         case FILE_SCHED_RELAX_DOMAIN_LEVEL:
                 retval = update_relax_domain_level(cs, val);
@@ -1384,6 +1432,32 @@ static int cpuset_write_s64(struct cgroup *cgrp, struct cftype *cft, s64 val)
 }
 
 /*
+ * Common handling for a write to a "cpus" or "mems" file.
+ */
+static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
+                                const char *buf)
+{
+        int retval = 0;
+
+        if (!cgroup_lock_live_group(cgrp))
+                return -ENODEV;
+
+        switch (cft->private) {
+        case FILE_CPULIST:
+                retval = update_cpumask(cgroup_cs(cgrp), buf);
+                break;
+        case FILE_MEMLIST:
+                retval = update_nodemask(cgroup_cs(cgrp), buf);
+                break;
+        default:
+                retval = -EINVAL;
+                break;
+        }
+        cgroup_unlock();
+        return retval;
+}
+
+/*
  * These ascii lists should be read in a single call, by using a user
  * buffer large enough to hold the entire map.  If read in smaller
  * chunks, there is no guarantee of atomicity.  Since the display format
@@ -1479,6 +1553,9 @@ static u64 cpuset_read_u64(struct cgroup *cont, struct cftype *cft)
         default:
                 BUG();
         }
+
+        /* Unreachable but makes gcc happy */
+        return 0;
 }
 
 static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft)
@@ -1491,6 +1568,9 @@ static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft)
         default:
                 BUG();
         }
+
+        /* Unrechable but makes gcc happy */
+        return 0;
 }
 
 
@@ -1502,14 +1582,16 @@ static struct cftype files[] = {
         {
                 .name = "cpus",
                 .read = cpuset_common_file_read,
-                .write = cpuset_common_file_write,
+                .write_string = cpuset_write_resmask,
+                .max_write_len = (100U + 6 * NR_CPUS),
                 .private = FILE_CPULIST,
         },
 
         {
                 .name = "mems",
                 .read = cpuset_common_file_read,
-                .write = cpuset_common_file_write,
+                .write_string = cpuset_write_resmask,
+                .max_write_len = (100U + 6 * MAX_NUMNODES),
                 .private = FILE_MEMLIST,
         },
 
@@ -1677,15 +1759,9 @@ static struct cgroup_subsys_state *cpuset_create(
 }
 
 /*
- * Locking note on the strange update_flag() call below:
- *
  * If the cpuset being removed has its flag 'sched_load_balance'
  * enabled, then simulate turning sched_load_balance off, which
- * will call rebuild_sched_domains().  The get_online_cpus()
- * call in rebuild_sched_domains() must not be made while holding
- * callback_mutex.  Elsewhere the kernel nests callback_mutex inside
- * get_online_cpus() calls.  So the reverse nesting would risk an
- * ABBA deadlock.
+ * will call async_rebuild_sched_domains().
  */
 
 static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
@@ -1704,7 +1780,7 @@ static void cpuset_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
 struct cgroup_subsys cpuset_subsys = {
         .name = "cpuset",
         .create = cpuset_create,
-        .destroy  = cpuset_destroy,
+        .destroy = cpuset_destroy,
         .can_attach = cpuset_can_attach,
         .attach = cpuset_attach,
         .populate = cpuset_populate,
@@ -1790,13 +1866,13 @@ static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to)
         scan.scan.heap = NULL;
         scan.to = to->css.cgroup;
 
-        if (cgroup_scan_tasks((struct cgroup_scanner *)&scan))
+        if (cgroup_scan_tasks(&scan.scan))
                 printk(KERN_ERR "move_member_tasks_to_cpuset: "
                                 "cgroup_scan_tasks failed\n");
 }
 
 /*
- * If common_cpu_mem_hotplug_unplug(), below, unplugs any CPUs
+ * If CPU and/or memory hotplug handlers, below, unplug any CPUs
  * or memory nodes, we need to walk over the cpuset hierarchy,
  * removing that CPU or node from all cpusets.  If this removes the
  * last CPU or node from a cpuset, then move the tasks in the empty
@@ -1844,31 +1920,31 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
  * that has tasks along with an empty 'mems'.  But if we did see such
  * a cpuset, we'd handle it just like we do if its 'cpus' was empty.
  */
-static void scan_for_empty_cpusets(const struct cpuset *root)
+static void scan_for_empty_cpusets(struct cpuset *root)
 {
+        LIST_HEAD(queue);
         struct cpuset *cp;      /* scans cpusets being updated */
         struct cpuset *child;   /* scans child cpusets of cp */
-        struct list_head queue;
         struct cgroup *cont;
-
-        INIT_LIST_HEAD(&queue);
+        nodemask_t oldmems;
 
         list_add_tail((struct list_head *)&root->stack_list, &queue);
 
         while (!list_empty(&queue)) {
-                cp = container_of(queue.next, struct cpuset, stack_list);
+                cp = list_first_entry(&queue, struct cpuset, stack_list);
                 list_del(queue.next);
                 list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
                         child = cgroup_cs(cont);
                         list_add_tail(&child->stack_list, &queue);
                 }
-                cont = cp->css.cgroup;
 
                 /* Continue past cpusets with all cpus, mems online */
                 if (cpus_subset(cp->cpus_allowed, cpu_online_map) &&
                     nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))
                         continue;
 
+                oldmems = cp->mems_allowed;
+
                 /* Remove offline cpus and mems from this cpuset. */
                 mutex_lock(&callback_mutex);
                 cpus_and(cp->cpus_allowed, cp->cpus_allowed, cpu_online_map);
@@ -1880,39 +1956,14 @@ static void scan_for_empty_cpusets(const struct cpuset *root)
                 if (cpus_empty(cp->cpus_allowed) ||
                      nodes_empty(cp->mems_allowed))
                         remove_tasks_in_empty_cpuset(cp);
+                else {
+                        update_tasks_cpumask(cp, NULL);
+                        update_tasks_nodemask(cp, &oldmems);
+                }
         }
 }
 
 /*
- * The cpus_allowed and mems_allowed nodemasks in the top_cpuset track
- * cpu_online_map and node_states[N_HIGH_MEMORY].  Force the top cpuset to
- * track what's online after any CPU or memory node hotplug or unplug event.
- *
- * Since there are two callers of this routine, one for CPU hotplug
- * events and one for memory node hotplug events, we could have coded
- * two separate routines here.  We code it as a single common routine
- * in order to minimize text size.
- */
-
-static void common_cpu_mem_hotplug_unplug(int rebuild_sd)
-{
-        cgroup_lock();
-
-        top_cpuset.cpus_allowed = cpu_online_map;
-        top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
-        scan_for_empty_cpusets(&top_cpuset);
-
-        /*
-         * Scheduler destroys domains on hotplug events.
-         * Rebuild them based on the current settings.
-         */
-        if (rebuild_sd)
-                rebuild_sched_domains();
-
-        cgroup_unlock();
-}
-
-/*
  * The top_cpuset tracks what CPUs and Memory Nodes are online,
  * period.  This is necessary in order to make cpusets transparent
  * (of no affect) on systems that are actively using CPU hotplug
@@ -1920,40 +1971,52 @@ static void common_cpu_mem_hotplug_unplug(int rebuild_sd)
  *
  * This routine ensures that top_cpuset.cpus_allowed tracks
  * cpu_online_map on each CPU hotplug (cpuhp) event.
+ *
+ * Called within get_online_cpus().  Needs to call cgroup_lock()
+ * before calling generate_sched_domains().
  */
-
-static int cpuset_handle_cpuhp(struct notifier_block *unused_nb,
+static int cpuset_track_online_cpus(struct notifier_block *unused_nb,
                                 unsigned long phase, void *unused_cpu)
 {
+        struct sched_domain_attr *attr;
+        cpumask_t *doms;
+        int ndoms;
+
         switch (phase) {
-        case CPU_UP_CANCELED:
-        case CPU_UP_CANCELED_FROZEN:
-        case CPU_DOWN_FAILED:
-        case CPU_DOWN_FAILED_FROZEN:
         case CPU_ONLINE:
         case CPU_ONLINE_FROZEN:
         case CPU_DEAD:
         case CPU_DEAD_FROZEN:
-                common_cpu_mem_hotplug_unplug(1);
                 break;
+
         default:
                 return NOTIFY_DONE;
         }
 
+        cgroup_lock();
+        top_cpuset.cpus_allowed = cpu_online_map;
+        scan_for_empty_cpusets(&top_cpuset);
+        ndoms = generate_sched_domains(&doms, &attr);
+        cgroup_unlock();
+
+        /* Have scheduler rebuild the domains */
+        partition_sched_domains(ndoms, doms, attr);
+
         return NOTIFY_OK;
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
 /*
  * Keep top_cpuset.mems_allowed tracking node_states[N_HIGH_MEMORY].
- * Call this routine anytime after you change
- * node_states[N_HIGH_MEMORY].
- * See also the previous routine cpuset_handle_cpuhp().
+ * Call this routine anytime after node_states[N_HIGH_MEMORY] changes.
+ * See also the previous routine cpuset_track_online_cpus().
  */
-
 void cpuset_track_online_nodes(void)
 {
-        common_cpu_mem_hotplug_unplug(0);
+        cgroup_lock();
+        top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
+        scan_for_empty_cpusets(&top_cpuset);
+        cgroup_unlock();
 }
 #endif
 
@@ -1968,11 +2031,10 @@ void __init cpuset_init_smp(void)
         top_cpuset.cpus_allowed = cpu_online_map;
         top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
 
-        hotcpu_notifier(cpuset_handle_cpuhp, 0);
+        hotcpu_notifier(cpuset_track_online_cpus, 0);
 }
 
 /**
-
  * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
  * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
  * @pmask: pointer to cpumask_t variable to receive cpus_allowed set.
@@ -2374,19 +2436,15 @@ const struct file_operations proc_cpuset_operations = {
 void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
 {
         seq_printf(m, "Cpus_allowed:\t");
-        m->count += cpumask_scnprintf(m->buf + m->count, m->size - m->count,
-                                        task->cpus_allowed);
+        seq_cpumask(m, &task->cpus_allowed);
         seq_printf(m, "\n");
         seq_printf(m, "Cpus_allowed_list:\t");
-        m->count += cpulist_scnprintf(m->buf + m->count, m->size - m->count,
-                                        task->cpus_allowed);
+        seq_cpumask_list(m, &task->cpus_allowed);
         seq_printf(m, "\n");
         seq_printf(m, "Mems_allowed:\t");
-        m->count += nodemask_scnprintf(m->buf + m->count, m->size - m->count,
-                                        task->mems_allowed);
+        seq_nodemask(m, &task->mems_allowed);
         seq_printf(m, "\n");
         seq_printf(m, "Mems_allowed_list:\t");
-        m->count += nodelist_scnprintf(m->buf + m->count, m->size - m->count,
-                                        task->mems_allowed);
+        seq_nodemask_list(m, &task->mems_allowed);
         seq_printf(m, "\n");
 }