1 files changed, 119 insertions, 135 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index f76db9dcaa05..026faccca869 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -128,10 +128,6 @@ static inline struct cpuset *task_cs(struct task_struct *task)
         return container_of(task_subsys_state(task, cpuset_subsys_id),
                             struct cpuset, css);
 }
-struct cpuset_hotplug_scanner {
-        struct cgroup_scanner scan;
-        struct cgroup *to;
-};
 
 /* bits in struct cpuset flags field */
 typedef enum {
@@ -521,6 +517,7 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
         return 0;
 }
 
+#ifdef CONFIG_SMP
 /*
  * Helper routine for generate_sched_domains().
  * Do cpusets a, b have overlapping cpus_allowed masks?
@@ -815,6 +812,18 @@ static void do_rebuild_sched_domains(struct work_struct *unused)
 
         put_online_cpus();
 }
+#else /* !CONFIG_SMP */
+static void do_rebuild_sched_domains(struct work_struct *unused)
+{
+}
+
+static int generate_sched_domains(struct cpumask **domains,
+                        struct sched_domain_attr **attributes)
+{
+        *domains = NULL;
+        return 1;
+}
+#endif /* CONFIG_SMP */
 
 static DECLARE_WORK(rebuild_sched_domains_work, do_rebuild_sched_domains);
 
@@ -1026,101 +1035,70 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
         mutex_unlock(&callback_mutex);
 }
 
+/*
+ * Rebind task's vmas to cpuset's new mems_allowed, and migrate pages to new
+ * nodes if memory_migrate flag is set. Called with cgroup_mutex held.
+ */
+static void cpuset_change_nodemask(struct task_struct *p,
+                                   struct cgroup_scanner *scan)
+{
+        struct mm_struct *mm;
+        struct cpuset *cs;
+        int migrate;
+        const nodemask_t *oldmem = scan->data;
+
+        mm = get_task_mm(p);
+        if (!mm)
+                return;
+
+        cs = cgroup_cs(scan->cg);
+        migrate = is_memory_migrate(cs);
+
+        mpol_rebind_mm(mm, &cs->mems_allowed);
+        if (migrate)
+                cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
+        mmput(mm);
+}
+
 static void *cpuset_being_rebound;
 
 /**
  * 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
+ * @heap: if NULL, defer allocating heap memory to cgroup_scan_tasks()
  *
  * Called with cgroup_mutex held
- * Return 0 if successful, -errno if not.
+ * No return value. It's guaranteed that cgroup_scan_tasks() always returns 0
+ * if @heap != NULL.
  */
-static int update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem)
+static void update_tasks_nodemask(struct cpuset *cs, const nodemask_t *oldmem,
+                                 struct ptr_heap *heap)
 {
-        struct task_struct *p;
-        struct mm_struct **mmarray;
-        int i, n, ntasks;
-        int migrate;
-        int fudge;
-        struct cgroup_iter it;
-        int retval;
+        struct cgroup_scanner scan;
 
         cpuset_being_rebound = cs;              /* causes mpol_dup() rebind */
 
-        fudge = 10;                             /* spare mmarray[] slots */
-        fudge += cpumask_weight(cs->cpus_allowed);/* imagine 1 fork-bomb/cpu */
-        retval = -ENOMEM;
-
-        /*
-         * Allocate mmarray[] to hold mm reference for each task
-         * in cpuset cs.  Can't kmalloc GFP_KERNEL while holding
-         * tasklist_lock.  We could use GFP_ATOMIC, but with a
-         * few more lines of code, we can retry until we get a big
-         * enough mmarray[] w/o using GFP_ATOMIC.
-         */
-        while (1) {
-                ntasks = cgroup_task_count(cs->css.cgroup);  /* guess */
-                ntasks += fudge;
-                mmarray = kmalloc(ntasks * sizeof(*mmarray), GFP_KERNEL);
-                if (!mmarray)
-                        goto done;
-                read_lock(&tasklist_lock);              /* block fork */
-                if (cgroup_task_count(cs->css.cgroup) <= ntasks)
-                        break;                          /* got enough */
-                read_unlock(&tasklist_lock);            /* try again */
-                kfree(mmarray);
-        }
-
-        n = 0;
-
-        /* Load up mmarray[] with mm reference for each task in cpuset. */
-        cgroup_iter_start(cs->css.cgroup, &it);
-        while ((p = cgroup_iter_next(cs->css.cgroup, &it))) {
-                struct mm_struct *mm;
-
-                if (n >= ntasks) {
-                        printk(KERN_WARNING
-                                "Cpuset mempolicy rebind incomplete.\n");
-                        break;
-                }
-                mm = get_task_mm(p);
-                if (!mm)
-                        continue;
-                mmarray[n++] = mm;
-        }
-        cgroup_iter_end(cs->css.cgroup, &it);
-        read_unlock(&tasklist_lock);
+        scan.cg = cs->css.cgroup;
+        scan.test_task = NULL;
+        scan.process_task = cpuset_change_nodemask;
+        scan.heap = heap;
+        scan.data = (nodemask_t *)oldmem;
 
         /*
-         * Now that we've dropped the tasklist spinlock, we can
-         * rebind the vma mempolicies of each mm in mmarray[] to their
-         * new cpuset, and release that mm.  The mpol_rebind_mm()
-         * call takes mmap_sem, which we couldn't take while holding
-         * tasklist_lock.  Forks can happen again now - the mpol_dup()
-         * cpuset_being_rebound check will catch such forks, and rebind
-         * their vma mempolicies too.  Because we still hold the global
-         * cgroup_mutex, we know that no other rebind effort will
-         * be contending for the global variable cpuset_being_rebound.
+         * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
+         * take while holding tasklist_lock.  Forks can happen - the
+         * mpol_dup() cpuset_being_rebound check will catch such forks,
+         * and rebind their vma mempolicies too.  Because we still hold
+         * the global cgroup_mutex, we know that no other rebind effort
+         * will be contending for the global variable cpuset_being_rebound.
          * It's ok if we rebind the same mm twice; mpol_rebind_mm()
          * is idempotent.  Also migrate pages in each mm to new nodes.
          */
-        migrate = is_memory_migrate(cs);
-        for (i = 0; i < n; i++) {
-                struct mm_struct *mm = mmarray[i];
-
-                mpol_rebind_mm(mm, &cs->mems_allowed);
-                if (migrate)
-                        cpuset_migrate_mm(mm, oldmem, &cs->mems_allowed);
-                mmput(mm);
-        }
+        cgroup_scan_tasks(&scan);
 
         /* We're done rebinding vmas to this cpuset's new mems_allowed. */
-        kfree(mmarray);
         cpuset_being_rebound = NULL;
-        retval = 0;
-done:
-        return retval;
 }
 
 /*
@@ -1141,6 +1119,7 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
 {
         nodemask_t oldmem;
         int retval;
+        struct ptr_heap heap;
 
         /*
          * top_cpuset.mems_allowed tracks node_stats[N_HIGH_MEMORY];
@@ -1175,12 +1154,18 @@ static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
         if (retval < 0)
                 goto done;
 
+        retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
+        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);
+        update_tasks_nodemask(cs, &oldmem, &heap);
+
+        heap_free(&heap);
 done:
         return retval;
 }
@@ -1192,8 +1177,10 @@ int current_cpuset_is_being_rebound(void)
 
 static int update_relax_domain_level(struct cpuset *cs, s64 val)
 {
+#ifdef CONFIG_SMP
         if (val < -1 || val >= SD_LV_MAX)
                 return -EINVAL;
+#endif
 
         if (val != cs->relax_domain_level) {
                 cs->relax_domain_level = val;
@@ -1355,19 +1342,22 @@ static int cpuset_can_attach(struct cgroup_subsys *ss,
                              struct cgroup *cont, struct task_struct *tsk)
 {
         struct cpuset *cs = cgroup_cs(cont);
-        int ret = 0;
 
         if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
                 return -ENOSPC;
 
-        if (tsk->flags & PF_THREAD_BOUND) {
-                mutex_lock(&callback_mutex);
-                if (!cpumask_equal(&tsk->cpus_allowed, cs->cpus_allowed))
-                        ret = -EINVAL;
-                mutex_unlock(&callback_mutex);
-        }
+        /*
+         * Kthreads bound to specific cpus cannot be moved to a new cpuset; we
+         * cannot change their cpu affinity and isolating such threads by their
+         * set of allowed nodes is unnecessary.  Thus, cpusets are not
+         * applicable for such threads.  This prevents checking for success of
+         * set_cpus_allowed_ptr() on all attached tasks before cpus_allowed may
+         * be changed.
+         */
+        if (tsk->flags & PF_THREAD_BOUND)
+                return -EINVAL;
 
-        return ret < 0 ? ret : security_task_setscheduler(tsk, 0, NULL);
+        return security_task_setscheduler(tsk, 0, NULL);
 }
 
 static void cpuset_attach(struct cgroup_subsys *ss,
@@ -1706,6 +1696,7 @@ static struct cftype files[] = {
                 .read_u64 = cpuset_read_u64,
                 .write_u64 = cpuset_write_u64,
                 .private = FILE_MEMORY_PRESSURE,
+                .mode = S_IRUGO,
         },
 
         {
@@ -1913,10 +1904,9 @@ int __init cpuset_init(void)
 static void cpuset_do_move_task(struct task_struct *tsk,
                                 struct cgroup_scanner *scan)
 {
-        struct cpuset_hotplug_scanner *chsp;
+        struct cgroup *new_cgroup = scan->data;
 
-        chsp = container_of(scan, struct cpuset_hotplug_scanner, scan);
-        cgroup_attach_task(chsp->to, tsk);
+        cgroup_attach_task(new_cgroup, tsk);
 }
 
 /**
@@ -1932,15 +1922,15 @@ static void cpuset_do_move_task(struct task_struct *tsk,
  */
 static void move_member_tasks_to_cpuset(struct cpuset *from, struct cpuset *to)
 {
-        struct cpuset_hotplug_scanner scan;
+        struct cgroup_scanner scan;
 
-        scan.scan.cg = from->css.cgroup;
-        scan.scan.test_task = NULL; /* select all tasks in cgroup */
-        scan.scan.process_task = cpuset_do_move_task;
-        scan.scan.heap = NULL;
-        scan.to = to->css.cgroup;
+        scan.cg = from->css.cgroup;
+        scan.test_task = NULL; /* select all tasks in cgroup */
+        scan.process_task = cpuset_do_move_task;
+        scan.heap = NULL;
+        scan.data = to->css.cgroup;
 
-        if (cgroup_scan_tasks(&scan.scan))
+        if (cgroup_scan_tasks(&scan))
                 printk(KERN_ERR "move_member_tasks_to_cpuset: "
                                 "cgroup_scan_tasks failed\n");
 }
@@ -2033,7 +2023,7 @@ static void scan_for_empty_cpusets(struct cpuset *root)
                         remove_tasks_in_empty_cpuset(cp);
                 else {
                         update_tasks_cpumask(cp, NULL);
-                        update_tasks_nodemask(cp, &oldmems);
+                        update_tasks_nodemask(cp, &oldmems, NULL);
                 }
         }
 }
@@ -2069,7 +2059,9 @@ static int cpuset_track_online_cpus(struct notifier_block *unused_nb,
         }
 
         cgroup_lock();
+        mutex_lock(&callback_mutex);
         cpumask_copy(top_cpuset.cpus_allowed, cpu_online_mask);
+        mutex_unlock(&callback_mutex);
         scan_for_empty_cpusets(&top_cpuset);
         ndoms = generate_sched_domains(&doms, &attr);
         cgroup_unlock();
@@ -2092,11 +2084,12 @@ static int cpuset_track_online_nodes(struct notifier_block *self,
         cgroup_lock();
         switch (action) {
         case MEM_ONLINE:
-                top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
-                break;
         case MEM_OFFLINE:
+                mutex_lock(&callback_mutex);
                 top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY];
-                scan_for_empty_cpusets(&top_cpuset);
+                mutex_unlock(&callback_mutex);
+                if (action == MEM_OFFLINE)
+                        scan_for_empty_cpusets(&top_cpuset);
                 break;
         default:
                 break;
@@ -2206,26 +2199,24 @@ static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
 }
 
 /**
- * cpuset_zone_allowed_softwall - Can we allocate on zone z's memory node?
- * @z: is this zone on an allowed node?
+ * cpuset_node_allowed_softwall - Can we allocate on a memory node?
+ * @node: is this an allowed node?
  * @gfp_mask: memory allocation flags
  *
- * If we're in interrupt, yes, we can always allocate.  If
- * __GFP_THISNODE is set, yes, we can always allocate.  If zone
- * z's node is in our tasks mems_allowed, yes.  If it's not a
- * __GFP_HARDWALL request and this zone's nodes is in the nearest
- * hardwalled cpuset ancestor to this tasks cpuset, yes.
- * If the task has been OOM killed and has access to memory reserves
- * as specified by the TIF_MEMDIE flag, yes.
+ * If we're in interrupt, yes, we can always allocate.  If __GFP_THISNODE is
+ * set, yes, we can always allocate.  If node is in our task's mems_allowed,
+ * yes.  If it's not a __GFP_HARDWALL request and this node is in the nearest
+ * hardwalled cpuset ancestor to this task's cpuset, yes.  If the task has been
+ * OOM killed and has access to memory reserves as specified by the TIF_MEMDIE
+ * flag, yes.
  * Otherwise, no.
  *
- * If __GFP_HARDWALL is set, cpuset_zone_allowed_softwall()
- * reduces to cpuset_zone_allowed_hardwall().  Otherwise,
- * cpuset_zone_allowed_softwall() might sleep, and might allow a zone
- * from an enclosing cpuset.
+ * If __GFP_HARDWALL is set, cpuset_node_allowed_softwall() reduces to
+ * cpuset_node_allowed_hardwall().  Otherwise, cpuset_node_allowed_softwall()
+ * might sleep, and might allow a node from an enclosing cpuset.
  *
- * cpuset_zone_allowed_hardwall() only handles the simpler case of
- * hardwall cpusets, and never sleeps.
+ * cpuset_node_allowed_hardwall() only handles the simpler case of hardwall
+ * cpusets, and never sleeps.
  *
  * The __GFP_THISNODE placement logic is really handled elsewhere,
  * by forcibly using a zonelist starting at a specified node, and by
@@ -2264,20 +2255,17 @@ static const struct cpuset *nearest_hardwall_ancestor(const struct cpuset *cs)
  *      GFP_USER     - only nodes in current tasks mems allowed ok.
  *
  * Rule:
- *    Don't call cpuset_zone_allowed_softwall if you can't sleep, unless you
+ *    Don't call cpuset_node_allowed_softwall if you can't sleep, unless you
  *    pass in the __GFP_HARDWALL flag set in gfp_flag, which disables
  *    the code that might scan up ancestor cpusets and sleep.
  */
-
-int __cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
+int __cpuset_node_allowed_softwall(int node, gfp_t gfp_mask)
 {
-        int node;                       /* node that zone z is on */
         const struct cpuset *cs;        /* current cpuset ancestors */
         int allowed;                    /* is allocation in zone z allowed? */
 
         if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
                 return 1;
-        node = zone_to_nid(z);
         might_sleep_if(!(gfp_mask & __GFP_HARDWALL));
         if (node_isset(node, current->mems_allowed))
                 return 1;
@@ -2306,15 +2294,15 @@ int __cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
 }
 
 /*
- * cpuset_zone_allowed_hardwall - Can we allocate on zone z's memory node?
- * @z: is this zone on an allowed node?
+ * cpuset_node_allowed_hardwall - Can we allocate on a memory node?
+ * @node: is this an allowed node?
  * @gfp_mask: memory allocation flags
  *
- * If we're in interrupt, yes, we can always allocate.
- * If __GFP_THISNODE is set, yes, we can always allocate.  If zone
- * z's node is in our tasks mems_allowed, yes.   If the task has been
- * OOM killed and has access to memory reserves as specified by the
- * TIF_MEMDIE flag, yes.  Otherwise, no.
+ * If we're in interrupt, yes, we can always allocate.  If __GFP_THISNODE is
+ * set, yes, we can always allocate.  If node is in our task's mems_allowed,
+ * yes.  If the task has been OOM killed and has access to memory reserves as
+ * specified by the TIF_MEMDIE flag, yes.
+ * Otherwise, no.
  *
  * The __GFP_THISNODE placement logic is really handled elsewhere,
  * by forcibly using a zonelist starting at a specified node, and by
@@ -2322,20 +2310,16 @@ int __cpuset_zone_allowed_softwall(struct zone *z, gfp_t gfp_mask)
  * any node on the zonelist except the first.  By the time any such
  * calls get to this routine, we should just shut up and say 'yes'.
  *
- * Unlike the cpuset_zone_allowed_softwall() variant, above,
- * this variant requires that the zone be in the current tasks
+ * Unlike the cpuset_node_allowed_softwall() variant, above,
+ * this variant requires that the node be in the current task's
  * mems_allowed or that we're in interrupt.  It does not scan up the
  * cpuset hierarchy for the nearest enclosing mem_exclusive cpuset.
  * It never sleeps.
  */
-
-int __cpuset_zone_allowed_hardwall(struct zone *z, gfp_t gfp_mask)
+int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
 {
-        int node;                       /* node that zone z is on */
-
         if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
                 return 1;
-        node = zone_to_nid(z);
         if (node_isset(node, current->mems_allowed))
                 return 1;
         /*