1 files changed, 396 insertions, 309 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 9fceb97e989c..eab7bd6628e0 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;
@@ -1083,7 +1193,7 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
 	mutex_unlock(&callback_mutex);
 
 	if (cpus_nonempty && balance_flag_changed)
-		rebuild_sched_domains();
+		async_rebuild_sched_domains();
 
 	return 0;
 }
@@ -1194,6 +1304,15 @@ static int cpuset_can_attach(struct cgroup_subsys *ss,
 
 	if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
 		return -ENOSPC;
+	if (tsk->flags & PF_THREAD_BOUND) {
+		cpumask_t mask;
+
+		mutex_lock(&callback_mutex);
+		mask = cs->cpus_allowed;
+		mutex_unlock(&callback_mutex);
+		if (!cpus_equal(tsk->cpus_allowed, mask))
+			return -EINVAL;
+	}
 
 	return security_task_setscheduler(tsk, 0, NULL);
 }
@@ -1207,11 +1326,14 @@ static void cpuset_attach(struct cgroup_subsys *ss,
 	struct mm_struct *mm;
 	struct cpuset *cs = cgroup_cs(cont);
 	struct cpuset *oldcs = cgroup_cs(oldcont);
+	int err;
 
 	mutex_lock(&callback_mutex);
 	guarantee_online_cpus(cs, &cpus);
-	set_cpus_allowed_ptr(tsk, &cpus);
+	err = set_cpus_allowed_ptr(tsk, &cpus);
 	mutex_unlock(&callback_mutex);
+	if (err)
+		return;
 
 	from = oldcs->mems_allowed;
 	to = cs->mems_allowed;
@@ -1242,72 +1364,14 @@ 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:
@@ -1353,12 +1417,9 @@ 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);
@@ -1372,6 +1433,32 @@ 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
@@ -1467,6 +1554,9 @@ 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)
@@ -1479,6 +1569,9 @@ static s64 cpuset_read_s64(struct cgroup *cont, struct cftype *cft)
 	default:
 		BUG();
 	}
+
+	/* Unrechable but makes gcc happy */
+	return 0;
 }
 
 
@@ -1490,14 +1583,16 @@ 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,
 	},
 
@@ -1665,15 +1760,9 @@ 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)
@@ -1692,7 +1781,7 @@ 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,
@@ -1778,13 +1867,13 @@ 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
@@ -1832,31 +1921,31 @@ 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);
@@ -1868,38 +1957,14 @@ 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(void)
-{
-	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.
-	 */
-	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
@@ -1907,29 +1972,52 @@ static void common_cpu_mem_hotplug_unplug(void)
  *
  * 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)
 {
-	if (phase == CPU_DYING || phase == CPU_DYING_FROZEN)
+	struct sched_domain_attr *attr;
+	cpumask_t *doms;
+	int ndoms;
+
+	switch (phase) {
+	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		break;
+
+	default:
 		return NOTIFY_DONE;
+	}
 
-	common_cpu_mem_hotplug_unplug();
-	return 0;
+	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();
+	cgroup_lock();
+	top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
+	scan_for_empty_cpusets(&top_cpuset);
+	cgroup_unlock();
 }
 #endif
 
@@ -1944,11 +2032,10 @@ 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.