1 files changed, 24 insertions, 16 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 16395644a98f..059b38cae384 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -112,8 +112,6 @@ static void __exit_signal(struct task_struct *tsk)
                  * We won't ever get here for the group leader, since it
                  * will have been the last reference on the signal_struct.
                  */
-                sig->utime = cputime_add(sig->utime, task_utime(tsk));
-                sig->stime = cputime_add(sig->stime, task_stime(tsk));
                 sig->gtime = cputime_add(sig->gtime, task_gtime(tsk));
                 sig->min_flt += tsk->min_flt;
                 sig->maj_flt += tsk->maj_flt;
@@ -122,7 +120,6 @@ static void __exit_signal(struct task_struct *tsk)
                 sig->inblock += task_io_get_inblock(tsk);
                 sig->oublock += task_io_get_oublock(tsk);
                 task_io_accounting_add(&sig->ioac, &tsk->ioac);
-                sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
                 sig = NULL; /* Marker for below. */
         }
 
@@ -583,8 +580,6 @@ mm_need_new_owner(struct mm_struct *mm, struct task_struct *p)
          * If there are other users of the mm and the owner (us) is exiting
          * we need to find a new owner to take on the responsibility.
          */
-        if (!mm)
-                return 0;
         if (atomic_read(&mm->mm_users) <= 1)
                 return 0;
         if (mm->owner != p)
@@ -627,29 +622,38 @@ retry:
         } while_each_thread(g, c);
 
         read_unlock(&tasklist_lock);
+        /*
+         * We found no owner yet mm_users > 1: this implies that we are
+         * most likely racing with swapoff (try_to_unuse()) or /proc or
+         * ptrace or page migration (get_task_mm()).  Mark owner as NULL,
+         * so that subsystems can understand the callback and take action.
+         */
+        down_write(&mm->mmap_sem);
+        cgroup_mm_owner_callbacks(mm->owner, NULL);
+        mm->owner = NULL;
+        up_write(&mm->mmap_sem);
         return;
 
 assign_new_owner:
         BUG_ON(c == p);
         get_task_struct(c);
+        read_unlock(&tasklist_lock);
+        down_write(&mm->mmap_sem);
         /*
          * The task_lock protects c->mm from changing.
          * We always want mm->owner->mm == mm
          */
         task_lock(c);
-        /*
-         * Delay read_unlock() till we have the task_lock()
-         * to ensure that c does not slip away underneath us
-         */
-        read_unlock(&tasklist_lock);
         if (c->mm != mm) {
                 task_unlock(c);
+                up_write(&mm->mmap_sem);
                 put_task_struct(c);
                 goto retry;
         }
         cgroup_mm_owner_callbacks(mm->owner, c);
         mm->owner = c;
         task_unlock(c);
+        up_write(&mm->mmap_sem);
         put_task_struct(c);
 }
 #endif /* CONFIG_MM_OWNER */
@@ -1294,6 +1298,7 @@ static int wait_task_zombie(struct task_struct *p, int options,
         if (likely(!traced)) {
                 struct signal_struct *psig;
                 struct signal_struct *sig;
+                struct task_cputime cputime;
 
                 /*
                  * The resource counters for the group leader are in its
@@ -1309,20 +1314,23 @@ static int wait_task_zombie(struct task_struct *p, int options,
                  * need to protect the access to p->parent->signal fields,
                  * as other threads in the parent group can be right
                  * here reaping other children at the same time.
+                 *
+                 * We use thread_group_cputime() to get times for the thread
+                 * group, which consolidates times for all threads in the
+                 * group including the group leader.
                  */
                 spin_lock_irq(&p->parent->sighand->siglock);
                 psig = p->parent->signal;
                 sig = p->signal;
+                thread_group_cputime(p, &cputime);
                 psig->cutime =
                         cputime_add(psig->cutime,
-                        cputime_add(p->utime,
-                        cputime_add(sig->utime,
-                                    sig->cutime)));
+                        cputime_add(cputime.utime,
+                                    sig->cutime));
                 psig->cstime =
                         cputime_add(psig->cstime,
-                        cputime_add(p->stime,
-                        cputime_add(sig->stime,
-                                    sig->cstime)));
+                        cputime_add(cputime.stime,
+                                    sig->cstime));
                 psig->cgtime =
                         cputime_add(psig->cgtime,
                         cputime_add(p->gtime,