Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  cpuset: fix regression when failed to generate sched domains
  sched, signals: fix the racy usage of ->signal in account_group_xxx/run_posix_cpu_timers
  sched: fix kernel warning on /proc/sched_debug access
  sched: correct sched-rt-group.txt pathname in init/Kconfig

5 files changed, 34 insertions, 18 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 3e00526f52ec..81fc6791a296 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -587,7 +587,6 @@ static int generate_sched_domains(cpumask_t **domains,
         int ndoms;              /* number of sched domains in result */
         int nslot;              /* next empty doms[] cpumask_t slot */
 
-        ndoms = 0;
         doms = NULL;
         dattr = NULL;
         csa = NULL;
@@ -674,10 +673,8 @@ restart:
          * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
          */
         doms = kmalloc(ndoms * sizeof(cpumask_t), GFP_KERNEL);
-        if (!doms) {
-                ndoms = 0;
+        if (!doms)
                 goto done;
-        }
 
         /*
          * The rest of the code, including the scheduler, can deal with
@@ -732,6 +729,13 @@ restart:
 done:
         kfree(csa);
 
+        /*
+         * Fallback to the default domain if kmalloc() failed.
+         * See comments in partition_sched_domains().
+         */
+        if (doms == NULL)
+                ndoms = 1;
+
         *domains    = doms;
         *attributes = dattr;
         return ndoms;
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 153dcb2639c3..895337b16a24 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -1308,9 +1308,10 @@ static inline int task_cputime_expired(const struct task_cputime *sample,
  */
 static inline int fastpath_timer_check(struct task_struct *tsk)
 {
-        struct signal_struct *sig = tsk->signal;
+        struct signal_struct *sig;
 
-        if (unlikely(!sig))
+        /* tsk == current, ensure it is safe to use ->signal/sighand */
+        if (unlikely(tsk->exit_state))
                 return 0;
 
         if (!task_cputime_zero(&tsk->cputime_expires)) {
@@ -1323,6 +1324,8 @@ static inline int fastpath_timer_check(struct task_struct *tsk)
                 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
                         return 1;
         }
+
+        sig = tsk->signal;
         if (!task_cputime_zero(&sig->cputime_expires)) {
                 struct task_cputime group_sample;
 
diff --git a/kernel/sched.c b/kernel/sched.c
index c94baf2969e7..9b1e79371c20 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -7789,13 +7789,14 @@ static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
  *
  * The passed in 'doms_new' should be kmalloc'd. This routine takes
  * ownership of it and will kfree it when done with it. If the caller
- * failed the kmalloc call, then it can pass in doms_new == NULL,
- * and partition_sched_domains() will fallback to the single partition
- * 'fallback_doms', it also forces the domains to be rebuilt.
+ * failed the kmalloc call, then it can pass in doms_new == NULL &&
+ * ndoms_new == 1, and partition_sched_domains() will fallback to
+ * the single partition 'fallback_doms', it also forces the domains
+ * to be rebuilt.
  *
- * If doms_new==NULL it will be replaced with cpu_online_map.
- * ndoms_new==0 is a special case for destroying existing domains.
- * It will not create the default domain.
+ * If doms_new == NULL it will be replaced with cpu_online_map.
+ * ndoms_new == 0 is a special case for destroying existing domains,
+ * and it will not create the default domain.
  *
  * Call with hotplug lock held
  */
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 48ecc51e7701..26ed8e3d1c15 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -423,10 +423,11 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
 #undef __P
 
         {
+                unsigned int this_cpu = raw_smp_processor_id();
                 u64 t0, t1;
 
-                t0 = sched_clock();
-                t1 = sched_clock();
+                t0 = cpu_clock(this_cpu);
+                t1 = cpu_clock(this_cpu);
                 SEQ_printf(m, "%-35s:%21Ld\n",
                            "clock-delta", (long long)(t1-t0));
         }
diff --git a/kernel/sched_stats.h b/kernel/sched_stats.h
index ee71bec1da66..7dbf72a2b02c 100644
--- a/kernel/sched_stats.h
+++ b/kernel/sched_stats.h
@@ -298,9 +298,11 @@ static inline void account_group_user_time(struct task_struct *tsk,
 {
         struct signal_struct *sig;
 
-        sig = tsk->signal;
-        if (unlikely(!sig))
+        /* tsk == current, ensure it is safe to use ->signal */
+        if (unlikely(tsk->exit_state))
                 return;
+
+        sig = tsk->signal;
         if (sig->cputime.totals) {
                 struct task_cputime *times;
 
@@ -325,9 +327,11 @@ static inline void account_group_system_time(struct task_struct *tsk,
 {
         struct signal_struct *sig;
 
-        sig = tsk->signal;
-        if (unlikely(!sig))
+        /* tsk == current, ensure it is safe to use ->signal */
+        if (unlikely(tsk->exit_state))
                 return;
+
+        sig = tsk->signal;
         if (sig->cputime.totals) {
                 struct task_cputime *times;
 
@@ -353,8 +357,11 @@ static inline void account_group_exec_runtime(struct task_struct *tsk,
         struct signal_struct *sig;
 
         sig = tsk->signal;
+        /* see __exit_signal()->task_rq_unlock_wait() */
+        barrier();
         if (unlikely(!sig))
                 return;
+
         if (sig->cputime.totals) {
                 struct task_cputime *times;