1 files changed, 178 insertions, 185 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 459d601947a8..91cf85b36dd5 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -227,10 +227,6 @@ 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.
@@ -369,7 +365,7 @@ 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();
         }
 
@@ -500,11 +496,16 @@ update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
 /*
  * rebuild_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 will be called to rebuild the scheduler's dynamic
+ * 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 the 'sched_relax_domain_level' of any cpuset which has
+ *   that flag enabled and with non-empty 'cpus' changes,
+ * - or if any cpuset with non-empty 'cpus' is removed,
+ * - or if a cpu gets offlined.
  *
  * This routine builds a partial partition of the systems CPUs
  * (the set of non-overlappping cpumask_t's in the array 'part'
@@ -564,7 +565,7 @@ update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
  *      partition_sched_domains().
  */
 
-static void rebuild_sched_domains(void)
+void rebuild_sched_domains(void)
 {
         struct kfifo *q;        /* queue of cpusets to be scanned */
         struct cpuset *cp;      /* scans q */
@@ -609,8 +610,13 @@ static void rebuild_sched_domains(void)
         while (__kfifo_get(q, (void *)&cp, sizeof(cp))) {
                 struct cgroup *cont;
                 struct cpuset *child;   /* scans child cpusets of cp */
+
+                if (cpus_empty(cp->cpus_allowed))
+                        continue;
+
                 if (is_sched_load_balance(cp))
                         csa[csn++] = cp;
+
                 list_for_each_entry(cont, &cp->css.cgroup->children, sibling) {
                         child = cgroup_cs(cont);
                         __kfifo_put(q, (void *)&child, sizeof(cp));
@@ -679,7 +685,9 @@ restart:
                                 if (apn == b->pn) {
                                         cpus_or(*dp, *dp, b->cpus_allowed);
                                         b->pn = -1;
-                                        update_domain_attr(dattr, b);
+                                        if (dattr)
+                                                update_domain_attr(dattr
+                                                                   + nslot, b);
                                 }
                         }
                         nslot++;
@@ -701,36 +709,6 @@ done:
         /* Don't kfree(dattr) -- partition_sched_domains() does that. */
 }
 
-static inline int started_after_time(struct task_struct *t1,
-                                     struct timespec *time,
-                                     struct task_struct *t2)
-{
-        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;
-        }
-}
-
-static inline int started_after(void *p1, void *p2)
-{
-        struct task_struct *t1 = p1;
-        struct task_struct *t2 = p2;
-        return started_after_time(t1, &t2->start_time, t2);
-}
-
 /**
  * cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's
  * @tsk: task to test
@@ -766,15 +744,49 @@ 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
+ *
+ * Called with cgroup_mutex held
+ *
+ * The cgroup_scan_tasks() function will scan all the tasks in a cgroup,
+ * calling callback functions for each.
+ *
+ * Return 0 if successful, -errno if not.
+ */
+static int update_tasks_cpumask(struct cpuset *cs)
+{
+        struct cgroup_scanner scan;
+        struct ptr_heap heap;
+        int retval;
+
+        /*
+         * cgroup_scan_tasks() will initialize heap->gt for us.
+         * heap_init() is still needed here for we should not change
+         * cs->cpus_allowed when heap_init() fails.
+         */
+        retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
+        if (retval)
+                return retval;
+
+        scan.cg = cs->css.cgroup;
+        scan.test_task = cpuset_test_cpumask;
+        scan.process_task = cpuset_change_cpumask;
+        scan.heap = &heap;
+        retval = cgroup_scan_tasks(&scan);
+
+        heap_free(&heap);
+        return retval;
+}
+
+/**
  * 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;
         int retval;
         int is_load_balanced;
 
@@ -790,7 +802,6 @@ 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 {
@@ -809,10 +820,6 @@ 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);
-        if (retval)
-                return retval;
-
         is_load_balanced = is_sched_load_balance(&trialcs);
 
         mutex_lock(&callback_mutex);
@@ -823,12 +830,9 @@ 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);
-        heap_free(&heap);
+        retval = update_tasks_cpumask(cs);
+        if (retval < 0)
+                return retval;
 
         if (is_load_balanced)
                 rebuild_sched_domains();
@@ -884,74 +888,25 @@ 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 +973,7 @@ 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 +985,70 @@ 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 +1061,8 @@ 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))
+                        rebuild_sched_domains();
         }
 
         return 0;
@@ -1254,72 +1274,14 @@ 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 +1327,9 @@ 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 +1343,32 @@ 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
@@ -1502,14 +1487,16 @@ 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,
         },
 
@@ -1790,7 +1777,7 @@ 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");
 }
@@ -1850,6 +1837,7 @@ static void scan_for_empty_cpusets(const struct cpuset *root)
         struct cpuset *child;   /* scans child cpusets of cp */
         struct list_head queue;
         struct cgroup *cont;
+        nodemask_t oldmems;
 
         INIT_LIST_HEAD(&queue);
 
@@ -1869,6 +1857,8 @@ static void scan_for_empty_cpusets(const struct cpuset *root)
                     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);
@@ -1880,6 +1870,10 @@ 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);
+                        update_tasks_nodemask(cp, &oldmems);
+                }
         }
 }
 
@@ -1972,7 +1966,6 @@ void __init cpuset_init_smp(void)
 }
 
 /**
-
  * 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.