diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 655ed8d..a8635f6 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1333,20 +1333,15 @@
 	prstatus->pr_pgrp = task_pgrp_vnr(p);
 	prstatus->pr_sid = task_session_vnr(p);
 	if (thread_group_leader(p)) {
+		struct task_cputime cputime;
+
 		/*
-		 * This is the record for the group leader.  Add in the
-		 * cumulative times of previous dead threads.  This total
-		 * won't include the time of each live thread whose state
-		 * is included in the core dump.  The final total reported
-		 * to our parent process when it calls wait4 will include
-		 * those sums as well as the little bit more time it takes
-		 * this and each other thread to finish dying after the
-		 * core dump synchronization phase.
+		 * This is the record for the group leader.  It shows the
+		 * group-wide total, not its individual thread total.
 		 */
-		cputime_to_timeval(cputime_add(p->utime, p->signal->utime),
-				   &prstatus->pr_utime);
-		cputime_to_timeval(cputime_add(p->stime, p->signal->stime),
-				   &prstatus->pr_stime);
+		thread_group_cputime(p, &cputime);
+		cputime_to_timeval(cputime.utime, &prstatus->pr_utime);
+		cputime_to_timeval(cputime.stime, &prstatus->pr_stime);
 	} else {
 		cputime_to_timeval(p->utime, &prstatus->pr_utime);
 		cputime_to_timeval(p->stime, &prstatus->pr_stime);
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 71c9be5..933953c 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -395,20 +395,20 @@
 
 		/* add up live thread stats at the group level */
 		if (whole) {
+			struct task_cputime cputime;
 			struct task_struct *t = task;
 			do {
 				min_flt += t->min_flt;
 				maj_flt += t->maj_flt;
-				utime = cputime_add(utime, task_utime(t));
-				stime = cputime_add(stime, task_stime(t));
 				gtime = cputime_add(gtime, task_gtime(t));
 				t = next_thread(t);
 			} while (t != task);
 
 			min_flt += sig->min_flt;
 			maj_flt += sig->maj_flt;
-			utime = cputime_add(utime, sig->utime);
-			stime = cputime_add(stime, sig->stime);
+			thread_group_cputime(task, &cputime);
+			utime = cputime.utime;
+			stime = cputime.stime;
 			gtime = cputime_add(gtime, sig->gtime);
 		}
 
diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index a7dd38f..f9d8e9e 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -115,4 +115,6 @@
 
 long clock_nanosleep_restart(struct restart_block *restart_block);
 
+void update_rlimit_cpu(unsigned long rlim_new);
+
 #endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3d9120c..26d7a5f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -425,6 +425,45 @@
 	unsigned long		ac_minflt, ac_majflt;
 };
 
+/**
+ * struct task_cputime - collected CPU time counts
+ * @utime:		time spent in user mode, in &cputime_t units
+ * @stime:		time spent in kernel mode, in &cputime_t units
+ * @sum_exec_runtime:	total time spent on the CPU, in nanoseconds
+ * 
+ * This structure groups together three kinds of CPU time that are
+ * tracked for threads and thread groups.  Most things considering
+ * CPU time want to group these counts together and treat all three
+ * of them in parallel.
+ */
+struct task_cputime {
+	cputime_t utime;
+	cputime_t stime;
+	unsigned long long sum_exec_runtime;
+};
+/* Alternate field names when used to cache expirations. */
+#define prof_exp	stime
+#define virt_exp	utime
+#define sched_exp	sum_exec_runtime
+
+/**
+ * struct thread_group_cputime - thread group interval timer counts
+ * @totals:		thread group interval timers; substructure for
+ *			uniprocessor kernel, per-cpu for SMP kernel.
+ *
+ * This structure contains the version of task_cputime, above, that is
+ * used for thread group CPU clock calculations.
+ */
+#ifdef CONFIG_SMP
+struct thread_group_cputime {
+	struct task_cputime *totals;
+};
+#else
+struct thread_group_cputime {
+	struct task_cputime totals;
+};
+#endif
+
 /*
  * NOTE! "signal_struct" does not have it's own
  * locking, because a shared signal_struct always
@@ -470,6 +509,17 @@
 	cputime_t it_prof_expires, it_virt_expires;
 	cputime_t it_prof_incr, it_virt_incr;
 
+	/*
+	 * Thread group totals for process CPU clocks.
+	 * See thread_group_cputime(), et al, for details.
+	 */
+	struct thread_group_cputime cputime;
+
+	/* Earliest-expiration cache. */
+	struct task_cputime cputime_expires;
+
+	struct list_head cpu_timers[3];
+
 	/* job control IDs */
 
 	/*
@@ -500,7 +550,7 @@
 	 * Live threads maintain their own counters and add to these
 	 * in __exit_signal, except for the group leader.
 	 */
-	cputime_t utime, stime, cutime, cstime;
+	cputime_t cutime, cstime;
 	cputime_t gtime;
 	cputime_t cgtime;
 	unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
@@ -509,14 +559,6 @@
 	struct task_io_accounting ioac;
 
 	/*
-	 * Cumulative ns of scheduled CPU time for dead threads in the
-	 * group, not including a zombie group leader.  (This only differs
-	 * from jiffies_to_ns(utime + stime) if sched_clock uses something
-	 * other than jiffies.)
-	 */
-	unsigned long long sum_sched_runtime;
-
-	/*
 	 * We don't bother to synchronize most readers of this at all,
 	 * because there is no reader checking a limit that actually needs
 	 * to get both rlim_cur and rlim_max atomically, and either one
@@ -527,8 +569,6 @@
 	 */
 	struct rlimit rlim[RLIM_NLIMITS];
 
-	struct list_head cpu_timers[3];
-
 	/* keep the process-shared keyrings here so that they do the right
 	 * thing in threads created with CLONE_THREAD */
 #ifdef CONFIG_KEYS
@@ -1134,8 +1174,7 @@
 /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
 	unsigned long min_flt, maj_flt;
 
-  	cputime_t it_prof_expires, it_virt_expires;
-	unsigned long long it_sched_expires;
+	struct task_cputime cputime_expires;
 	struct list_head cpu_timers[3];
 
 /* process credentials */
@@ -1585,6 +1624,7 @@
 
 extern unsigned long long
 task_sched_runtime(struct task_struct *task);
+extern unsigned long long thread_group_sched_runtime(struct task_struct *task);
 
 /* sched_exec is called by processes performing an exec */
 #ifdef CONFIG_SMP
@@ -2082,6 +2122,197 @@
 }
 
 /*
+ * Thread group CPU time accounting.
+ */
+#ifdef CONFIG_SMP
+
+extern int thread_group_cputime_alloc_smp(struct task_struct *);
+extern void thread_group_cputime_smp(struct task_struct *, struct task_cputime *);
+
+static inline void thread_group_cputime_init(struct signal_struct *sig)
+{
+	sig->cputime.totals = NULL;
+}
+
+static inline int thread_group_cputime_clone_thread(struct task_struct *curr,
+						    struct task_struct *new)
+{
+	if (curr->signal->cputime.totals)
+		return 0;
+	return thread_group_cputime_alloc_smp(curr);
+}
+
+static inline void thread_group_cputime_free(struct signal_struct *sig)
+{
+	free_percpu(sig->cputime.totals);
+}
+
+/**
+ * thread_group_cputime - Sum the thread group time fields across all CPUs.
+ *
+ * This is a wrapper for the real routine, thread_group_cputime_smp().  See
+ * that routine for details.
+ */
+static inline void thread_group_cputime(
+	struct task_struct *tsk,
+	struct task_cputime *times)
+{
+	thread_group_cputime_smp(tsk, times);
+}
+
+/**
+ * thread_group_cputime_account_user - Maintain utime for a thread group.
+ *
+ * @tgtimes:	Pointer to thread_group_cputime structure.
+ * @cputime:	Time value by which to increment the utime field of that
+ *		structure.
+ *
+ * If thread group time is being maintained, get the structure for the
+ * running CPU and update the utime field there.
+ */
+static inline void thread_group_cputime_account_user(
+	struct thread_group_cputime *tgtimes,
+	cputime_t cputime)
+{
+	if (tgtimes->totals) {
+		struct task_cputime *times;
+
+		times = per_cpu_ptr(tgtimes->totals, get_cpu());
+		times->utime = cputime_add(times->utime, cputime);
+		put_cpu_no_resched();
+	}
+}
+
+/**
+ * thread_group_cputime_account_system - Maintain stime for a thread group.
+ *
+ * @tgtimes:	Pointer to thread_group_cputime structure.
+ * @cputime:	Time value by which to increment the stime field of that
+ *		structure.
+ *
+ * If thread group time is being maintained, get the structure for the
+ * running CPU and update the stime field there.
+ */
+static inline void thread_group_cputime_account_system(
+	struct thread_group_cputime *tgtimes,
+	cputime_t cputime)
+{
+	if (tgtimes->totals) {
+		struct task_cputime *times;
+
+		times = per_cpu_ptr(tgtimes->totals, get_cpu());
+		times->stime = cputime_add(times->stime, cputime);
+		put_cpu_no_resched();
+	}
+}
+
+/**
+ * thread_group_cputime_account_exec_runtime - Maintain exec runtime for a
+ *						thread group.
+ *
+ * @tgtimes:	Pointer to thread_group_cputime structure.
+ * @ns:		Time value by which to increment the sum_exec_runtime field
+ *		of that structure.
+ *
+ * If thread group time is being maintained, get the structure for the
+ * running CPU and update the sum_exec_runtime field there.
+ */
+static inline void thread_group_cputime_account_exec_runtime(
+	struct thread_group_cputime *tgtimes,
+	unsigned long long ns)
+{
+	if (tgtimes->totals) {
+		struct task_cputime *times;
+
+		times = per_cpu_ptr(tgtimes->totals, get_cpu());
+		times->sum_exec_runtime += ns;
+		put_cpu_no_resched();
+	}
+}
+
+#else /* CONFIG_SMP */
+
+static inline void thread_group_cputime_init(struct signal_struct *sig)
+{
+	sig->cputime.totals.utime = cputime_zero;
+	sig->cputime.totals.stime = cputime_zero;
+	sig->cputime.totals.sum_exec_runtime = 0;
+}
+
+static inline int thread_group_cputime_alloc(struct task_struct *tsk)
+{
+	return 0;
+}
+
+static inline void thread_group_cputime_free(struct signal_struct *sig)
+{
+}
+
+static inline int thread_group_cputime_clone_thread(struct task_struct *curr,
+						     struct task_struct *tsk)
+{
+}
+
+static inline void thread_group_cputime(struct task_struct *tsk,
+					 struct task_cputime *cputime)
+{
+	*cputime = tsk->signal->cputime.totals;
+}
+
+static inline void thread_group_cputime_account_user(
+	struct thread_group_cputime *tgtimes,
+	cputime_t cputime)
+{
+	tgtimes->totals->utime = cputime_add(tgtimes->totals->utime, cputime);
+}
+
+static inline void thread_group_cputime_account_system(
+	struct thread_group_cputime *tgtimes,
+	cputime_t cputime)
+{
+	tgtimes->totals->stime = cputime_add(tgtimes->totals->stime, cputime);
+}
+
+static inline void thread_group_cputime_account_exec_runtime(
+	struct thread_group_cputime *tgtimes,
+	unsigned long long ns)
+{
+	tgtimes->totals->sum_exec_runtime += ns;
+}
+
+#endif /* CONFIG_SMP */
+
+static inline void account_group_user_time(struct task_struct *tsk,
+					    cputime_t cputime)
+{
+	struct signal_struct *sig;
+
+	sig = tsk->signal;
+	if (likely(sig))
+		thread_group_cputime_account_user(&sig->cputime, cputime);
+}
+
+static inline void account_group_system_time(struct task_struct *tsk,
+					      cputime_t cputime)
+{
+	struct signal_struct *sig;
+
+	sig = tsk->signal;
+	if (likely(sig))
+		thread_group_cputime_account_system(&sig->cputime, cputime);
+}
+
+static inline void account_group_exec_runtime(struct task_struct *tsk,
+					       unsigned long long ns)
+{
+	struct signal_struct *sig;
+
+	sig = tsk->signal;
+	if (likely(sig))
+		thread_group_cputime_account_exec_runtime(&sig->cputime, ns);
+}
+
+/*
  * Reevaluate whether the task has signals pending delivery.
  * Wake the task if so.
  * This is required every time the blocked sigset_t changes.
diff --git a/include/linux/time.h b/include/linux/time.h
index e15206a..1b70b3c 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -125,6 +125,9 @@
 extern void update_wall_time(void);
 extern void update_xtime_cache(u64 nsec);
 
+struct tms;
+extern void do_sys_times(struct tms *);
+
 /**
  * timespec_to_ns - Convert timespec to nanoseconds
  * @ts:		pointer to the timespec variable to be converted
diff --git a/kernel/compat.c b/kernel/compat.c
index 32c254a..72650e3 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -23,6 +23,7 @@
 #include <linux/timex.h>
 #include <linux/migrate.h>
 #include <linux/posix-timers.h>
+#include <linux/times.h>
 
 #include <asm/uaccess.h>
 
@@ -150,49 +151,23 @@
 	return 0;
 }
 
+static compat_clock_t clock_t_to_compat_clock_t(clock_t x)
+{
+	return compat_jiffies_to_clock_t(clock_t_to_jiffies(x));
+}
+
 asmlinkage long compat_sys_times(struct compat_tms __user *tbuf)
 {
-	/*
-	 *	In the SMP world we might just be unlucky and have one of
-	 *	the times increment as we use it. Since the value is an
-	 *	atomically safe type this is just fine. Conceptually its
-	 *	as if the syscall took an instant longer to occur.
-	 */
 	if (tbuf) {
+		struct tms tms;
 		struct compat_tms tmp;
-		struct task_struct *tsk = current;
-		struct task_struct *t;
-		cputime_t utime, stime, cutime, cstime;
 
-		read_lock(&tasklist_lock);
-		utime = tsk->signal->utime;
-		stime = tsk->signal->stime;
-		t = tsk;
-		do {
-			utime = cputime_add(utime, t->utime);
-			stime = cputime_add(stime, t->stime);
-			t = next_thread(t);
-		} while (t != tsk);
-
-		/*
-		 * While we have tasklist_lock read-locked, no dying thread
-		 * can be updating current->signal->[us]time.  Instead,
-		 * we got their counts included in the live thread loop.
-		 * However, another thread can come in right now and
-		 * do a wait call that updates current->signal->c[us]time.
-		 * To make sure we always see that pair updated atomically,
-		 * we take the siglock around fetching them.
-		 */
-		spin_lock_irq(&tsk->sighand->siglock);
-		cutime = tsk->signal->cutime;
-		cstime = tsk->signal->cstime;
-		spin_unlock_irq(&tsk->sighand->siglock);
-		read_unlock(&tasklist_lock);
-
-		tmp.tms_utime = compat_jiffies_to_clock_t(cputime_to_jiffies(utime));
-		tmp.tms_stime = compat_jiffies_to_clock_t(cputime_to_jiffies(stime));
-		tmp.tms_cutime = compat_jiffies_to_clock_t(cputime_to_jiffies(cutime));
-		tmp.tms_cstime = compat_jiffies_to_clock_t(cputime_to_jiffies(cstime));
+		do_sys_times(&tms);
+		/* Convert our struct tms to the compat version. */
+		tmp.tms_utime = clock_t_to_compat_clock_t(tms.tms_utime);
+		tmp.tms_stime = clock_t_to_compat_clock_t(tms.tms_stime);
+		tmp.tms_cutime = clock_t_to_compat_clock_t(tms.tms_cutime);
+		tmp.tms_cstime = clock_t_to_compat_clock_t(tms.tms_cstime);
 		if (copy_to_user(tbuf, &tmp, sizeof(tmp)))
 			return -EFAULT;
 	}
diff --git a/kernel/exit.c b/kernel/exit.c
index 1639564..40036ac 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -112,8 +112,6 @@
 		 * 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 @@
 		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. */
 	}
 
@@ -1294,6 +1291,7 @@
 	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 +1307,23 @@
 		 * 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,
diff --git a/kernel/fork.c b/kernel/fork.c
index 7ce2ebe..a8ac2ef 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -759,15 +759,44 @@
 		kmem_cache_free(sighand_cachep, sighand);
 }
 
+
+/*
+ * Initialize POSIX timer handling for a thread group.
+ */
+static void posix_cpu_timers_init_group(struct signal_struct *sig)
+{
+	/* Thread group counters. */
+	thread_group_cputime_init(sig);
+
+	/* Expiration times and increments. */
+	sig->it_virt_expires = cputime_zero;
+	sig->it_virt_incr = cputime_zero;
+	sig->it_prof_expires = cputime_zero;
+	sig->it_prof_incr = cputime_zero;
+
+	/* Cached expiration times. */
+	sig->cputime_expires.prof_exp = cputime_zero;
+	sig->cputime_expires.virt_exp = cputime_zero;
+	sig->cputime_expires.sched_exp = 0;
+
+	/* The timer lists. */
+	INIT_LIST_HEAD(&sig->cpu_timers[0]);
+	INIT_LIST_HEAD(&sig->cpu_timers[1]);
+	INIT_LIST_HEAD(&sig->cpu_timers[2]);
+}
+
 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
 {
 	struct signal_struct *sig;
 	int ret;
 
 	if (clone_flags & CLONE_THREAD) {
-		atomic_inc(&current->signal->count);
-		atomic_inc(&current->signal->live);
-		return 0;
+		ret = thread_group_cputime_clone_thread(current, tsk);
+		if (likely(!ret)) {
+			atomic_inc(&current->signal->count);
+			atomic_inc(&current->signal->live);
+		}
+		return ret;
 	}
 	sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
 	tsk->signal = sig;
@@ -795,15 +824,10 @@
 	sig->it_real_incr.tv64 = 0;
 	sig->real_timer.function = it_real_fn;
 
-	sig->it_virt_expires = cputime_zero;
-	sig->it_virt_incr = cputime_zero;
-	sig->it_prof_expires = cputime_zero;
-	sig->it_prof_incr = cputime_zero;
-
 	sig->leader = 0;	/* session leadership doesn't inherit */
 	sig->tty_old_pgrp = NULL;
 
-	sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
+	sig->cutime = sig->cstime = cputime_zero;
 	sig->gtime = cputime_zero;
 	sig->cgtime = cputime_zero;
 	sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
@@ -820,14 +844,8 @@
 	memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
 	task_unlock(current->group_leader);
 
-	if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
-		/*
-		 * New sole thread in the process gets an expiry time
-		 * of the whole CPU time limit.
-		 */
-		tsk->it_prof_expires =
-			secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
-	}
+	posix_cpu_timers_init_group(sig);
+
 	acct_init_pacct(&sig->pacct);
 
 	tty_audit_fork(sig);
@@ -837,6 +855,7 @@
 
 void __cleanup_signal(struct signal_struct *sig)
 {
+	thread_group_cputime_free(sig);
 	exit_thread_group_keys(sig);
 	kmem_cache_free(signal_cachep, sig);
 }
@@ -886,6 +905,19 @@
 #endif /* CONFIG_MM_OWNER */
 
 /*
+ * Initialize POSIX timer handling for a single task.
+ */
+static void posix_cpu_timers_init(struct task_struct *tsk)
+{
+	tsk->cputime_expires.prof_exp = cputime_zero;
+	tsk->cputime_expires.virt_exp = cputime_zero;
+	tsk->cputime_expires.sched_exp = 0;
+	INIT_LIST_HEAD(&tsk->cpu_timers[0]);
+	INIT_LIST_HEAD(&tsk->cpu_timers[1]);
+	INIT_LIST_HEAD(&tsk->cpu_timers[2]);
+}
+
+/*
  * This creates a new process as a copy of the old one,
  * but does not actually start it yet.
  *
@@ -995,12 +1027,7 @@
 	task_io_accounting_init(&p->ioac);
 	acct_clear_integrals(p);
 
-	p->it_virt_expires = cputime_zero;
-	p->it_prof_expires = cputime_zero;
-	p->it_sched_expires = 0;
-	INIT_LIST_HEAD(&p->cpu_timers[0]);
-	INIT_LIST_HEAD(&p->cpu_timers[1]);
-	INIT_LIST_HEAD(&p->cpu_timers[2]);
+	posix_cpu_timers_init(p);
 
 	p->lock_depth = -1;		/* -1 = no lock */
 	do_posix_clock_monotonic_gettime(&p->start_time);
@@ -1201,21 +1228,6 @@
 	if (clone_flags & CLONE_THREAD) {
 		p->group_leader = current->group_leader;
 		list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
-
-		if (!cputime_eq(current->signal->it_virt_expires,
-				cputime_zero) ||
-		    !cputime_eq(current->signal->it_prof_expires,
-				cputime_zero) ||
-		    current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
-		    !list_empty(&current->signal->cpu_timers[0]) ||
-		    !list_empty(&current->signal->cpu_timers[1]) ||
-		    !list_empty(&current->signal->cpu_timers[2])) {
-			/*
-			 * Have child wake up on its first tick to check
-			 * for process CPU timers.
-			 */
-			p->it_prof_expires = jiffies_to_cputime(1);
-		}
 	}
 
 	if (likely(p->pid)) {
diff --git a/kernel/itimer.c b/kernel/itimer.c
index ab98274..db7c358 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -55,17 +55,15 @@
 		spin_unlock_irq(&tsk->sighand->siglock);
 		break;
 	case ITIMER_VIRTUAL:
-		read_lock(&tasklist_lock);
 		spin_lock_irq(&tsk->sighand->siglock);
 		cval = tsk->signal->it_virt_expires;
 		cinterval = tsk->signal->it_virt_incr;
 		if (!cputime_eq(cval, cputime_zero)) {
-			struct task_struct *t = tsk;
-			cputime_t utime = tsk->signal->utime;
-			do {
-				utime = cputime_add(utime, t->utime);
-				t = next_thread(t);
-			} while (t != tsk);
+			struct task_cputime cputime;
+			cputime_t utime;
+
+			thread_group_cputime(tsk, &cputime);
+			utime = cputime.utime;
 			if (cputime_le(cval, utime)) { /* about to fire */
 				cval = jiffies_to_cputime(1);
 			} else {
@@ -73,25 +71,19 @@
 			}
 		}
 		spin_unlock_irq(&tsk->sighand->siglock);
-		read_unlock(&tasklist_lock);
 		cputime_to_timeval(cval, &value->it_value);
 		cputime_to_timeval(cinterval, &value->it_interval);
 		break;
 	case ITIMER_PROF:
-		read_lock(&tasklist_lock);
 		spin_lock_irq(&tsk->sighand->siglock);
 		cval = tsk->signal->it_prof_expires;
 		cinterval = tsk->signal->it_prof_incr;
 		if (!cputime_eq(cval, cputime_zero)) {
-			struct task_struct *t = tsk;
-			cputime_t ptime = cputime_add(tsk->signal->utime,
-						      tsk->signal->stime);
-			do {
-				ptime = cputime_add(ptime,
-						    cputime_add(t->utime,
-								t->stime));
-				t = next_thread(t);
-			} while (t != tsk);
+			struct task_cputime times;
+			cputime_t ptime;
+
+			thread_group_cputime(tsk, &times);
+			ptime = cputime_add(times.utime, times.stime);
 			if (cputime_le(cval, ptime)) { /* about to fire */
 				cval = jiffies_to_cputime(1);
 			} else {
@@ -99,7 +91,6 @@
 			}
 		}
 		spin_unlock_irq(&tsk->sighand->siglock);
-		read_unlock(&tasklist_lock);
 		cputime_to_timeval(cval, &value->it_value);
 		cputime_to_timeval(cinterval, &value->it_interval);
 		break;
@@ -185,7 +176,6 @@
 	case ITIMER_VIRTUAL:
 		nval = timeval_to_cputime(&value->it_value);
 		ninterval = timeval_to_cputime(&value->it_interval);
-		read_lock(&tasklist_lock);
 		spin_lock_irq(&tsk->sighand->siglock);
 		cval = tsk->signal->it_virt_expires;
 		cinterval = tsk->signal->it_virt_incr;
@@ -200,7 +190,6 @@
 		tsk->signal->it_virt_expires = nval;
 		tsk->signal->it_virt_incr = ninterval;
 		spin_unlock_irq(&tsk->sighand->siglock);
-		read_unlock(&tasklist_lock);
 		if (ovalue) {
 			cputime_to_timeval(cval, &ovalue->it_value);
 			cputime_to_timeval(cinterval, &ovalue->it_interval);
@@ -209,7 +198,6 @@
 	case ITIMER_PROF:
 		nval = timeval_to_cputime(&value->it_value);
 		ninterval = timeval_to_cputime(&value->it_interval);
-		read_lock(&tasklist_lock);
 		spin_lock_irq(&tsk->sighand->siglock);
 		cval = tsk->signal->it_prof_expires;
 		cinterval = tsk->signal->it_prof_incr;
@@ -224,7 +212,6 @@
 		tsk->signal->it_prof_expires = nval;
 		tsk->signal->it_prof_incr = ninterval;
 		spin_unlock_irq(&tsk->sighand->siglock);
-		read_unlock(&tasklist_lock);
 		if (ovalue) {
 			cputime_to_timeval(cval, &ovalue->it_value);
 			cputime_to_timeval(cinterval, &ovalue->it_interval);
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index c42a03a..dba1c33 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -8,6 +8,99 @@
 #include <linux/math64.h>
 #include <asm/uaccess.h>
 
+#ifdef CONFIG_SMP
+/*
+ * Allocate the thread_group_cputime structure appropriately for SMP kernels
+ * and fill in the current values of the fields.  Called from copy_signal()
+ * via thread_group_cputime_clone_thread() when adding a second or subsequent
+ * thread to a thread group.  Assumes interrupts are enabled when called.
+ */
+int thread_group_cputime_alloc_smp(struct task_struct *tsk)
+{
+	struct signal_struct *sig = tsk->signal;
+	struct task_cputime *cputime;
+
+	/*
+	 * If we have multiple threads and we don't already have a
+	 * per-CPU task_cputime struct, allocate one and fill it in with
+	 * the times accumulated so far.
+	 */
+	if (sig->cputime.totals)
+		return 0;
+	cputime = alloc_percpu(struct task_cputime);
+	if (cputime == NULL)
+		return -ENOMEM;
+	read_lock(&tasklist_lock);
+	spin_lock_irq(&tsk->sighand->siglock);
+	if (sig->cputime.totals) {
+		spin_unlock_irq(&tsk->sighand->siglock);
+		read_unlock(&tasklist_lock);
+		free_percpu(cputime);
+		return 0;
+	}
+	sig->cputime.totals = cputime;
+	cputime = per_cpu_ptr(sig->cputime.totals, get_cpu());
+	cputime->utime = tsk->utime;
+	cputime->stime = tsk->stime;
+	cputime->sum_exec_runtime = tsk->se.sum_exec_runtime;
+	put_cpu_no_resched();
+	spin_unlock_irq(&tsk->sighand->siglock);
+	read_unlock(&tasklist_lock);
+	return 0;
+}
+
+/**
+ * thread_group_cputime_smp - Sum the thread group time fields across all CPUs.
+ *
+ * @tsk:	The task we use to identify the thread group.
+ * @times:	task_cputime structure in which we return the summed fields.
+ *
+ * Walk the list of CPUs to sum the per-CPU time fields in the thread group
+ * time structure.
+ */
+void thread_group_cputime_smp(
+	struct task_struct *tsk,
+	struct task_cputime *times)
+{
+	struct signal_struct *sig;
+	int i;
+	struct task_cputime *tot;
+
+	sig = tsk->signal;
+	if (unlikely(!sig) || !sig->cputime.totals) {
+		times->utime = tsk->utime;
+		times->stime = tsk->stime;
+		times->sum_exec_runtime = tsk->se.sum_exec_runtime;
+		return;
+	}
+	times->stime = times->utime = cputime_zero;
+	times->sum_exec_runtime = 0;
+	for_each_possible_cpu(i) {
+		tot = per_cpu_ptr(tsk->signal->cputime.totals, i);
+		times->utime = cputime_add(times->utime, tot->utime);
+		times->stime = cputime_add(times->stime, tot->stime);
+		times->sum_exec_runtime += tot->sum_exec_runtime;
+	}
+}
+
+#endif /* CONFIG_SMP */
+
+/*
+ * Called after updating RLIMIT_CPU to set timer expiration if necessary.
+ */
+void update_rlimit_cpu(unsigned long rlim_new)
+{
+	cputime_t cputime;
+
+	cputime = secs_to_cputime(rlim_new);
+	if (cputime_eq(current->signal->it_prof_expires, cputime_zero) ||
+            cputime_lt(current->signal->it_prof_expires, cputime)) {
+		spin_lock_irq(&current->sighand->siglock);
+		set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
+		spin_unlock_irq(&current->sighand->siglock);
+	}
+}
+
 static int check_clock(const clockid_t which_clock)
 {
 	int error = 0;
@@ -158,10 +251,6 @@
 {
 	return p->utime;
 }
-static inline unsigned long long sched_ns(struct task_struct *p)
-{
-	return task_sched_runtime(p);
-}
 
 int posix_cpu_clock_getres(const clockid_t which_clock, struct timespec *tp)
 {
@@ -211,7 +300,7 @@
 		cpu->cpu = virt_ticks(p);
 		break;
 	case CPUCLOCK_SCHED:
-		cpu->sched = sched_ns(p);
+		cpu->sched = task_sched_runtime(p);
 		break;
 	}
 	return 0;
@@ -226,31 +315,20 @@
 					 struct task_struct *p,
 					 union cpu_time_count *cpu)
 {
-	struct task_struct *t = p;
- 	switch (clock_idx) {
+	struct task_cputime cputime;
+
+	thread_group_cputime(p, &cputime);
+	switch (clock_idx) {
 	default:
 		return -EINVAL;
 	case CPUCLOCK_PROF:
-		cpu->cpu = cputime_add(p->signal->utime, p->signal->stime);
-		do {
-			cpu->cpu = cputime_add(cpu->cpu, prof_ticks(t));
-			t = next_thread(t);
-		} while (t != p);
+		cpu->cpu = cputime_add(cputime.utime, cputime.stime);
 		break;
 	case CPUCLOCK_VIRT:
-		cpu->cpu = p->signal->utime;
-		do {
-			cpu->cpu = cputime_add(cpu->cpu, virt_ticks(t));
-			t = next_thread(t);
-		} while (t != p);
+		cpu->cpu = cputime.utime;
 		break;
 	case CPUCLOCK_SCHED:
-		cpu->sched = p->signal->sum_sched_runtime;
-		/* Add in each other live thread.  */
-		while ((t = next_thread(t)) != p) {
-			cpu->sched += t->se.sum_exec_runtime;
-		}
-		cpu->sched += sched_ns(p);
+		cpu->sched = thread_group_sched_runtime(p);
 		break;
 	}
 	return 0;
@@ -471,80 +549,11 @@
 }
 void posix_cpu_timers_exit_group(struct task_struct *tsk)
 {
+	struct task_cputime cputime;
+
+	thread_group_cputime(tsk, &cputime);
 	cleanup_timers(tsk->signal->cpu_timers,
-		       cputime_add(tsk->utime, tsk->signal->utime),
-		       cputime_add(tsk->stime, tsk->signal->stime),
-		     tsk->se.sum_exec_runtime + tsk->signal->sum_sched_runtime);
-}
-
-
-/*
- * Set the expiry times of all the threads in the process so one of them
- * will go off before the process cumulative expiry total is reached.
- */
-static void process_timer_rebalance(struct task_struct *p,
-				    unsigned int clock_idx,
-				    union cpu_time_count expires,
-				    union cpu_time_count val)
-{
-	cputime_t ticks, left;
-	unsigned long long ns, nsleft;
- 	struct task_struct *t = p;
-	unsigned int nthreads = atomic_read(&p->signal->live);
-
-	if (!nthreads)
-		return;
-
-	switch (clock_idx) {
-	default:
-		BUG();
-		break;
-	case CPUCLOCK_PROF:
-		left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu),
-				       nthreads);
-		do {
-			if (likely(!(t->flags & PF_EXITING))) {
-				ticks = cputime_add(prof_ticks(t), left);
-				if (cputime_eq(t->it_prof_expires,
-					       cputime_zero) ||
-				    cputime_gt(t->it_prof_expires, ticks)) {
-					t->it_prof_expires = ticks;
-				}
-			}
-			t = next_thread(t);
-		} while (t != p);
-		break;
-	case CPUCLOCK_VIRT:
-		left = cputime_div_non_zero(cputime_sub(expires.cpu, val.cpu),
-				       nthreads);
-		do {
-			if (likely(!(t->flags & PF_EXITING))) {
-				ticks = cputime_add(virt_ticks(t), left);
-				if (cputime_eq(t->it_virt_expires,
-					       cputime_zero) ||
-				    cputime_gt(t->it_virt_expires, ticks)) {
-					t->it_virt_expires = ticks;
-				}
-			}
-			t = next_thread(t);
-		} while (t != p);
-		break;
-	case CPUCLOCK_SCHED:
-		nsleft = expires.sched - val.sched;
-		do_div(nsleft, nthreads);
-		nsleft = max_t(unsigned long long, nsleft, 1);
-		do {
-			if (likely(!(t->flags & PF_EXITING))) {
-				ns = t->se.sum_exec_runtime + nsleft;
-				if (t->it_sched_expires == 0 ||
-				    t->it_sched_expires > ns) {
-					t->it_sched_expires = ns;
-				}
-			}
-			t = next_thread(t);
-		} while (t != p);
-		break;
-	}
+		       cputime.utime, cputime.stime, cputime.sum_exec_runtime);
 }
 
 static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
@@ -608,29 +617,32 @@
 			default:
 				BUG();
 			case CPUCLOCK_PROF:
-				if (cputime_eq(p->it_prof_expires,
+				if (cputime_eq(p->cputime_expires.prof_exp,
 					       cputime_zero) ||
-				    cputime_gt(p->it_prof_expires,
+				    cputime_gt(p->cputime_expires.prof_exp,
 					       nt->expires.cpu))
-					p->it_prof_expires = nt->expires.cpu;
+					p->cputime_expires.prof_exp =
+						nt->expires.cpu;
 				break;
 			case CPUCLOCK_VIRT:
-				if (cputime_eq(p->it_virt_expires,
+				if (cputime_eq(p->cputime_expires.virt_exp,
 					       cputime_zero) ||
-				    cputime_gt(p->it_virt_expires,
+				    cputime_gt(p->cputime_expires.virt_exp,
 					       nt->expires.cpu))
-					p->it_virt_expires = nt->expires.cpu;
+					p->cputime_expires.virt_exp =
+						nt->expires.cpu;
 				break;
 			case CPUCLOCK_SCHED:
-				if (p->it_sched_expires == 0 ||
-				    p->it_sched_expires > nt->expires.sched)
-					p->it_sched_expires = nt->expires.sched;
+				if (p->cputime_expires.sched_exp == 0 ||
+				    p->cputime_expires.sched_exp >
+							nt->expires.sched)
+					p->cputime_expires.sched_exp =
+						nt->expires.sched;
 				break;
 			}
 		} else {
 			/*
-			 * For a process timer, we must balance
-			 * all the live threads' expirations.
+			 * For a process timer, set the cached expiration time.
 			 */
 			switch (CPUCLOCK_WHICH(timer->it_clock)) {
 			default:
@@ -641,7 +653,9 @@
 				    cputime_lt(p->signal->it_virt_expires,
 					       timer->it.cpu.expires.cpu))
 					break;
-				goto rebalance;
+				p->signal->cputime_expires.virt_exp =
+					timer->it.cpu.expires.cpu;
+				break;
 			case CPUCLOCK_PROF:
 				if (!cputime_eq(p->signal->it_prof_expires,
 						cputime_zero) &&
@@ -652,13 +666,12 @@
 				if (i != RLIM_INFINITY &&
 				    i <= cputime_to_secs(timer->it.cpu.expires.cpu))
 					break;
-				goto rebalance;
+				p->signal->cputime_expires.prof_exp =
+					timer->it.cpu.expires.cpu;
+				break;
 			case CPUCLOCK_SCHED:
-			rebalance:
-				process_timer_rebalance(
-					timer->it.cpu.task,
-					CPUCLOCK_WHICH(timer->it_clock),
-					timer->it.cpu.expires, now);
+				p->signal->cputime_expires.sched_exp =
+					timer->it.cpu.expires.sched;
 				break;
 			}
 		}
@@ -969,13 +982,13 @@
 	struct signal_struct *const sig = tsk->signal;
 
 	maxfire = 20;
-	tsk->it_prof_expires = cputime_zero;
+	tsk->cputime_expires.prof_exp = cputime_zero;
 	while (!list_empty(timers)) {
 		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
 		if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
-			tsk->it_prof_expires = t->expires.cpu;
+			tsk->cputime_expires.prof_exp = t->expires.cpu;
 			break;
 		}
 		t->firing = 1;
@@ -984,13 +997,13 @@
 
 	++timers;
 	maxfire = 20;
-	tsk->it_virt_expires = cputime_zero;
+	tsk->cputime_expires.virt_exp = cputime_zero;
 	while (!list_empty(timers)) {
 		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
 		if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
-			tsk->it_virt_expires = t->expires.cpu;
+			tsk->cputime_expires.virt_exp = t->expires.cpu;
 			break;
 		}
 		t->firing = 1;
@@ -999,13 +1012,13 @@
 
 	++timers;
 	maxfire = 20;
-	tsk->it_sched_expires = 0;
+	tsk->cputime_expires.sched_exp = 0;
 	while (!list_empty(timers)) {
 		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
 		if (!--maxfire || tsk->se.sum_exec_runtime < t->expires.sched) {
-			tsk->it_sched_expires = t->expires.sched;
+			tsk->cputime_expires.sched_exp = t->expires.sched;
 			break;
 		}
 		t->firing = 1;
@@ -1055,10 +1068,10 @@
 {
 	int maxfire;
 	struct signal_struct *const sig = tsk->signal;
-	cputime_t utime, stime, ptime, virt_expires, prof_expires;
+	cputime_t utime, ptime, virt_expires, prof_expires;
 	unsigned long long sum_sched_runtime, sched_expires;
-	struct task_struct *t;
 	struct list_head *timers = sig->cpu_timers;
+	struct task_cputime cputime;
 
 	/*
 	 * Don't sample the current process CPU clocks if there are no timers.
@@ -1074,18 +1087,10 @@
 	/*
 	 * Collect the current process totals.
 	 */
-	utime = sig->utime;
-	stime = sig->stime;
-	sum_sched_runtime = sig->sum_sched_runtime;
-	t = tsk;
-	do {
-		utime = cputime_add(utime, t->utime);
-		stime = cputime_add(stime, t->stime);
-		sum_sched_runtime += t->se.sum_exec_runtime;
-		t = next_thread(t);
-	} while (t != tsk);
-	ptime = cputime_add(utime, stime);
-
+	thread_group_cputime(tsk, &cputime);
+	utime = cputime.utime;
+	ptime = cputime_add(utime, cputime.stime);
+	sum_sched_runtime = cputime.sum_exec_runtime;
 	maxfire = 20;
 	prof_expires = cputime_zero;
 	while (!list_empty(timers)) {
@@ -1193,60 +1198,18 @@
 		}
 	}
 
-	if (!cputime_eq(prof_expires, cputime_zero) ||
-	    !cputime_eq(virt_expires, cputime_zero) ||
-	    sched_expires != 0) {
-		/*
-		 * Rebalance the threads' expiry times for the remaining
-		 * process CPU timers.
-		 */
-
-		cputime_t prof_left, virt_left, ticks;
-		unsigned long long sched_left, sched;
-		const unsigned int nthreads = atomic_read(&sig->live);
-
-		if (!nthreads)
-			return;
-
-		prof_left = cputime_sub(prof_expires, utime);
-		prof_left = cputime_sub(prof_left, stime);
-		prof_left = cputime_div_non_zero(prof_left, nthreads);
-		virt_left = cputime_sub(virt_expires, utime);
-		virt_left = cputime_div_non_zero(virt_left, nthreads);
-		if (sched_expires) {
-			sched_left = sched_expires - sum_sched_runtime;
-			do_div(sched_left, nthreads);
-			sched_left = max_t(unsigned long long, sched_left, 1);
-		} else {
-			sched_left = 0;
-		}
-		t = tsk;
-		do {
-			if (unlikely(t->flags & PF_EXITING))
-				continue;
-
-			ticks = cputime_add(cputime_add(t->utime, t->stime),
-					    prof_left);
-			if (!cputime_eq(prof_expires, cputime_zero) &&
-			    (cputime_eq(t->it_prof_expires, cputime_zero) ||
-			     cputime_gt(t->it_prof_expires, ticks))) {
-				t->it_prof_expires = ticks;
-			}
-
-			ticks = cputime_add(t->utime, virt_left);
-			if (!cputime_eq(virt_expires, cputime_zero) &&
-			    (cputime_eq(t->it_virt_expires, cputime_zero) ||
-			     cputime_gt(t->it_virt_expires, ticks))) {
-				t->it_virt_expires = ticks;
-			}
-
-			sched = t->se.sum_exec_runtime + sched_left;
-			if (sched_expires && (t->it_sched_expires == 0 ||
-					      t->it_sched_expires > sched)) {
-				t->it_sched_expires = sched;
-			}
-		} while ((t = next_thread(t)) != tsk);
-	}
+	if (!cputime_eq(prof_expires, cputime_zero) &&
+	    (cputime_eq(sig->cputime_expires.prof_exp, cputime_zero) ||
+	     cputime_gt(sig->cputime_expires.prof_exp, prof_expires)))
+		sig->cputime_expires.prof_exp = prof_expires;
+	if (!cputime_eq(virt_expires, cputime_zero) &&
+	    (cputime_eq(sig->cputime_expires.virt_exp, cputime_zero) ||
+	     cputime_gt(sig->cputime_expires.virt_exp, virt_expires)))
+		sig->cputime_expires.virt_exp = virt_expires;
+	if (sched_expires != 0 &&
+	    (sig->cputime_expires.sched_exp == 0 ||
+	     sig->cputime_expires.sched_exp > sched_expires))
+		sig->cputime_expires.sched_exp = sched_expires;
 }
 
 /*
@@ -1314,6 +1277,78 @@
 	++timer->it_requeue_pending;
 }
 
+/**
+ * task_cputime_zero - Check a task_cputime struct for all zero fields.
+ *
+ * @cputime:	The struct to compare.
+ *
+ * Checks @cputime to see if all fields are zero.  Returns true if all fields
+ * are zero, false if any field is nonzero.
+ */
+static inline int task_cputime_zero(const struct task_cputime *cputime)
+{
+	if (cputime_eq(cputime->utime, cputime_zero) &&
+	    cputime_eq(cputime->stime, cputime_zero) &&
+	    cputime->sum_exec_runtime == 0)
+		return 1;
+	return 0;
+}
+
+/**
+ * task_cputime_expired - Compare two task_cputime entities.
+ *
+ * @sample:	The task_cputime structure to be checked for expiration.
+ * @expires:	Expiration times, against which @sample will be checked.
+ *
+ * Checks @sample against @expires to see if any field of @sample has expired.
+ * Returns true if any field of the former is greater than the corresponding
+ * field of the latter if the latter field is set.  Otherwise returns false.
+ */
+static inline int task_cputime_expired(const struct task_cputime *sample,
+					const struct task_cputime *expires)
+{
+	if (!cputime_eq(expires->utime, cputime_zero) &&
+	    cputime_ge(sample->utime, expires->utime))
+		return 1;
+	if (!cputime_eq(expires->stime, cputime_zero) &&
+	    cputime_ge(cputime_add(sample->utime, sample->stime),
+		       expires->stime))
+		return 1;
+	if (expires->sum_exec_runtime != 0 &&
+	    sample->sum_exec_runtime >= expires->sum_exec_runtime)
+		return 1;
+	return 0;
+}
+
+/**
+ * fastpath_timer_check - POSIX CPU timers fast path.
+ *
+ * @tsk:	The task (thread) being checked.
+ * @sig:	The signal pointer for that task.
+ *
+ * If there are no timers set return false.  Otherwise snapshot the task and
+ * thread group timers, then compare them with the corresponding expiration
+ # times.  Returns true if a timer has expired, else returns false.
+ */
+static inline int fastpath_timer_check(struct task_struct *tsk,
+					struct signal_struct *sig)
+{
+	struct task_cputime task_sample = {
+		.utime = tsk->utime,
+		.stime = tsk->stime,
+		.sum_exec_runtime = tsk->se.sum_exec_runtime
+	};
+	struct task_cputime group_sample;
+
+	if (task_cputime_zero(&tsk->cputime_expires) &&
+	    task_cputime_zero(&sig->cputime_expires))
+		return 0;
+	if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
+		return 1;
+	thread_group_cputime(tsk, &group_sample);
+	return task_cputime_expired(&group_sample, &sig->cputime_expires);
+}
+
 /*
  * This is called from the timer interrupt handler.  The irq handler has
  * already updated our counts.  We need to check if any timers fire now.
@@ -1323,30 +1358,29 @@
 {
 	LIST_HEAD(firing);
 	struct k_itimer *timer, *next;
+	struct signal_struct *sig;
+	struct sighand_struct *sighand;
+	unsigned long flags;
 
 	BUG_ON(!irqs_disabled());
 
-#define UNEXPIRED(clock) \
-		(cputime_eq(tsk->it_##clock##_expires, cputime_zero) || \
-		 cputime_lt(clock##_ticks(tsk), tsk->it_##clock##_expires))
-
-	if (UNEXPIRED(prof) && UNEXPIRED(virt) &&
-	    (tsk->it_sched_expires == 0 ||
-	     tsk->se.sum_exec_runtime < tsk->it_sched_expires))
-		return;
-
-#undef	UNEXPIRED
-
+	/* Pick up tsk->signal and make sure it's valid. */
+	sig = tsk->signal;
 	/*
-	 * Double-check with locks held.
+	 * The fast path checks that there are no expired thread or thread
+	 * group timers.  If that's so, just return.  Also check that
+	 * tsk->signal is non-NULL; this probably can't happen but cover the
+	 * possibility anyway.
 	 */
-	read_lock(&tasklist_lock);
-	if (likely(tsk->signal != NULL)) {
-		spin_lock(&tsk->sighand->siglock);
-
+	if (unlikely(!sig) || !fastpath_timer_check(tsk, sig)) {
+		return;
+	}
+	sighand = lock_task_sighand(tsk, &flags);
+	if (likely(sighand)) {
 		/*
-		 * Here we take off tsk->cpu_timers[N] and tsk->signal->cpu_timers[N]
-		 * all the timers that are firing, and put them on the firing list.
+		 * Here we take off tsk->signal->cpu_timers[N] and
+		 * tsk->cpu_timers[N] all the timers that are firing, and
+		 * put them on the firing list.
 		 */
 		check_thread_timers(tsk, &firing);
 		check_process_timers(tsk, &firing);
@@ -1359,9 +1393,8 @@
 		 * that gets the timer lock before we do will give it up and
 		 * spin until we've taken care of that timer below.
 		 */
-		spin_unlock(&tsk->sighand->siglock);
 	}
-	read_unlock(&tasklist_lock);
+	unlock_task_sighand(tsk, &flags);
 
 	/*
 	 * Now that all the timers on our list have the firing flag,
@@ -1389,10 +1422,9 @@
 
 /*
  * Set one of the process-wide special case CPU timers.
- * The tasklist_lock and tsk->sighand->siglock must be held by the caller.
- * The oldval argument is null for the RLIMIT_CPU timer, where *newval is
- * absolute; non-null for ITIMER_*, where *newval is relative and we update
- * it to be absolute, *oldval is absolute and we update it to be relative.
+ * The tsk->sighand->siglock must be held by the caller.
+ * The *newval argument is relative and we update it to be absolute, *oldval
+ * is absolute and we update it to be relative.
  */
 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
 			   cputime_t *newval, cputime_t *oldval)
@@ -1435,13 +1467,14 @@
 	    cputime_ge(list_first_entry(head,
 				  struct cpu_timer_list, entry)->expires.cpu,
 		       *newval)) {
-		/*
-		 * Rejigger each thread's expiry time so that one will
-		 * notice before we hit the process-cumulative expiry time.
-		 */
-		union cpu_time_count expires = { .sched = 0 };
-		expires.cpu = *newval;
-		process_timer_rebalance(tsk, clock_idx, expires, now);
+		switch (clock_idx) {
+		case CPUCLOCK_PROF:
+			tsk->signal->cputime_expires.prof_exp = *newval;
+			break;
+		case CPUCLOCK_VIRT:
+			tsk->signal->cputime_expires.virt_exp = *newval;
+			break;
+		}
 	}
 }
 
diff --git a/kernel/sched.c b/kernel/sched.c
index cc1f81b..c51b5d2 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4037,23 +4037,56 @@
 EXPORT_PER_CPU_SYMBOL(kstat);
 
 /*
+ * Return any ns on the sched_clock that have not yet been banked in
+ * @p in case that task is currently running.
+ *
+ * Called with task_rq_lock() held on @rq.
+ */
+static unsigned long long task_delta_exec(struct task_struct *p, struct rq *rq)
+{
+	if (task_current(rq, p)) {
+		u64 delta_exec;
+
+		update_rq_clock(rq);
+		delta_exec = rq->clock - p->se.exec_start;
+		if ((s64)delta_exec > 0)
+			return delta_exec;
+	}
+	return 0;
+}
+
+/*
  * Return p->sum_exec_runtime plus any more ns on the sched_clock
  * that have not yet been banked in case the task is currently running.
  */
 unsigned long long task_sched_runtime(struct task_struct *p)
 {
 	unsigned long flags;
-	u64 ns, delta_exec;
+	u64 ns;
 	struct rq *rq;
 
 	rq = task_rq_lock(p, &flags);
-	ns = p->se.sum_exec_runtime;
-	if (task_current(rq, p)) {
-		update_rq_clock(rq);
-		delta_exec = rq->clock - p->se.exec_start;
-		if ((s64)delta_exec > 0)
-			ns += delta_exec;
-	}
+	ns = p->se.sum_exec_runtime + task_delta_exec(p, rq);
+	task_rq_unlock(rq, &flags);
+
+	return ns;
+}
+
+/*
+ * Return sum_exec_runtime for the thread group plus any more ns on the
+ * sched_clock that have not yet been banked in case the task is currently
+ * running.
+ */
+unsigned long long thread_group_sched_runtime(struct task_struct *p)
+{
+	unsigned long flags;
+	u64 ns;
+	struct rq *rq;
+	struct task_cputime totals;
+
+	rq = task_rq_lock(p, &flags);
+	thread_group_cputime(p, &totals);
+	ns = totals.sum_exec_runtime + task_delta_exec(p, rq);
 	task_rq_unlock(rq, &flags);
 
 	return ns;
@@ -4070,6 +4103,7 @@
 	cputime64_t tmp;
 
 	p->utime = cputime_add(p->utime, cputime);
+	account_group_user_time(p, cputime);
 
 	/* Add user time to cpustat. */
 	tmp = cputime_to_cputime64(cputime);
@@ -4094,6 +4128,7 @@
 	tmp = cputime_to_cputime64(cputime);
 
 	p->utime = cputime_add(p->utime, cputime);
+	account_group_user_time(p, cputime);
 	p->gtime = cputime_add(p->gtime, cputime);
 
 	cpustat->user = cputime64_add(cpustat->user, tmp);
@@ -4129,6 +4164,7 @@
 	}
 
 	p->stime = cputime_add(p->stime, cputime);
+	account_group_system_time(p, cputime);
 
 	/* Add system time to cpustat. */
 	tmp = cputime_to_cputime64(cputime);
@@ -4170,6 +4206,7 @@
 
 	if (p == rq->idle) {
 		p->stime = cputime_add(p->stime, steal);
+		account_group_system_time(p, steal);
 		if (atomic_read(&rq->nr_iowait) > 0)
 			cpustat->iowait = cputime64_add(cpustat->iowait, tmp);
 		else
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index fb8994c..99aa31a 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -507,6 +507,7 @@
 		struct task_struct *curtask = task_of(curr);
 
 		cpuacct_charge(curtask, delta_exec);
+		account_group_exec_runtime(curtask, delta_exec);
 	}
 }
 
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 5523107..8375e69 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -483,6 +483,8 @@
 	schedstat_set(curr->se.exec_max, max(curr->se.exec_max, delta_exec));
 
 	curr->se.sum_exec_runtime += delta_exec;
+	account_group_exec_runtime(curr, delta_exec);
+
 	curr->se.exec_start = rq->clock;
 	cpuacct_charge(curr, delta_exec);
 
@@ -1412,7 +1414,7 @@
 		p->rt.timeout++;
 		next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
 		if (p->rt.timeout > next)
-			p->it_sched_expires = p->se.sum_exec_runtime;
+			p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
 	}
 }
 
diff --git a/kernel/signal.c b/kernel/signal.c
index e661b01..6eea582 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1338,6 +1338,7 @@
 	struct siginfo info;
 	unsigned long flags;
 	struct sighand_struct *psig;
+	struct task_cputime cputime;
 	int ret = sig;
 
 	BUG_ON(sig == -1);
@@ -1368,10 +1369,9 @@
 
 	info.si_uid = tsk->uid;
 
-	info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
-						       tsk->signal->utime));
-	info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
-						       tsk->signal->stime));
+	thread_group_cputime(tsk, &cputime);
+	info.si_utime = cputime_to_jiffies(cputime.utime);
+	info.si_stime = cputime_to_jiffies(cputime.stime);
 
 	info.si_status = tsk->exit_code & 0x7f;
 	if (tsk->exit_code & 0x80)
diff --git a/kernel/sys.c b/kernel/sys.c
index 038a7bc..d046a7a 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -853,38 +853,28 @@
 	return old_fsgid;
 }
 
+void do_sys_times(struct tms *tms)
+{
+	struct task_cputime cputime;
+	cputime_t cutime, cstime;
+
+	spin_lock_irq(&current->sighand->siglock);
+	thread_group_cputime(current, &cputime);
+	cutime = current->signal->cutime;
+	cstime = current->signal->cstime;
+	spin_unlock_irq(&current->sighand->siglock);
+	tms->tms_utime = cputime_to_clock_t(cputime.utime);
+	tms->tms_stime = cputime_to_clock_t(cputime.stime);
+	tms->tms_cutime = cputime_to_clock_t(cutime);
+	tms->tms_cstime = cputime_to_clock_t(cstime);
+}
+
 asmlinkage long sys_times(struct tms __user * tbuf)
 {
-	/*
-	 *	In the SMP world we might just be unlucky and have one of
-	 *	the times increment as we use it. Since the value is an
-	 *	atomically safe type this is just fine. Conceptually its
-	 *	as if the syscall took an instant longer to occur.
-	 */
 	if (tbuf) {
 		struct tms tmp;
-		struct task_struct *tsk = current;
-		struct task_struct *t;
-		cputime_t utime, stime, cutime, cstime;
 
-		spin_lock_irq(&tsk->sighand->siglock);
-		utime = tsk->signal->utime;
-		stime = tsk->signal->stime;
-		t = tsk;
-		do {
-			utime = cputime_add(utime, t->utime);
-			stime = cputime_add(stime, t->stime);
-			t = next_thread(t);
-		} while (t != tsk);
-
-		cutime = tsk->signal->cutime;
-		cstime = tsk->signal->cstime;
-		spin_unlock_irq(&tsk->sighand->siglock);
-
-		tmp.tms_utime = cputime_to_clock_t(utime);
-		tmp.tms_stime = cputime_to_clock_t(stime);
-		tmp.tms_cutime = cputime_to_clock_t(cutime);
-		tmp.tms_cstime = cputime_to_clock_t(cstime);
+		do_sys_times(&tmp);
 		if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
 			return -EFAULT;
 	}
@@ -1445,7 +1435,6 @@
 asmlinkage long sys_setrlimit(unsigned int resource, struct rlimit __user *rlim)
 {
 	struct rlimit new_rlim, *old_rlim;
-	unsigned long it_prof_secs;
 	int retval;
 
 	if (resource >= RLIM_NLIMITS)
@@ -1491,18 +1480,7 @@
 	if (new_rlim.rlim_cur == RLIM_INFINITY)
 		goto out;
 
-	it_prof_secs = cputime_to_secs(current->signal->it_prof_expires);
-	if (it_prof_secs == 0 || new_rlim.rlim_cur <= it_prof_secs) {
-		unsigned long rlim_cur = new_rlim.rlim_cur;
-		cputime_t cputime;
-
-		cputime = secs_to_cputime(rlim_cur);
-		read_lock(&tasklist_lock);
-		spin_lock_irq(&current->sighand->siglock);
-		set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);
-		spin_unlock_irq(&current->sighand->siglock);
-		read_unlock(&tasklist_lock);
-	}
+	update_rlimit_cpu(new_rlim.rlim_cur);
 out:
 	return 0;
 }
@@ -1540,11 +1518,8 @@
  *
  */
 
-static void accumulate_thread_rusage(struct task_struct *t, struct rusage *r,
-				     cputime_t *utimep, cputime_t *stimep)
+static void accumulate_thread_rusage(struct task_struct *t, struct rusage *r)
 {
-	*utimep = cputime_add(*utimep, t->utime);
-	*stimep = cputime_add(*stimep, t->stime);
 	r->ru_nvcsw += t->nvcsw;
 	r->ru_nivcsw += t->nivcsw;
 	r->ru_minflt += t->min_flt;
@@ -1558,12 +1533,13 @@
 	struct task_struct *t;
 	unsigned long flags;
 	cputime_t utime, stime;
+	struct task_cputime cputime;
 
 	memset((char *) r, 0, sizeof *r);
 	utime = stime = cputime_zero;
 
 	if (who == RUSAGE_THREAD) {
-		accumulate_thread_rusage(p, r, &utime, &stime);
+		accumulate_thread_rusage(p, r);
 		goto out;
 	}
 
@@ -1586,8 +1562,9 @@
 				break;
 
 		case RUSAGE_SELF:
-			utime = cputime_add(utime, p->signal->utime);
-			stime = cputime_add(stime, p->signal->stime);
+			thread_group_cputime(p, &cputime);
+			utime = cputime_add(utime, cputime.utime);
+			stime = cputime_add(stime, cputime.stime);
 			r->ru_nvcsw += p->signal->nvcsw;
 			r->ru_nivcsw += p->signal->nivcsw;
 			r->ru_minflt += p->signal->min_flt;
@@ -1596,7 +1573,7 @@
 			r->ru_oublock += p->signal->oublock;
 			t = p;
 			do {
-				accumulate_thread_rusage(t, r, &utime, &stime);
+				accumulate_thread_rusage(t, r);
 				t = next_thread(t);
 			} while (t != p);
 			break;
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 03fc6a8..6964978 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -75,6 +75,7 @@
 #include <linux/string.h>
 #include <linux/selinux.h>
 #include <linux/mutex.h>
+#include <linux/posix-timers.h>
 
 #include "avc.h"
 #include "objsec.h"
@@ -2321,13 +2322,7 @@
 			initrlim = init_task.signal->rlim+i;
 			rlim->rlim_cur = min(rlim->rlim_max, initrlim->rlim_cur);
 		}
-		if (current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
-			/*
-			 * This will cause RLIMIT_CPU calculations
-			 * to be refigured.
-			 */
-			current->it_prof_expires = jiffies_to_cputime(1);
-		}
+		update_rlimit_cpu(rlim->rlim_cur);
 	}
 
 	/* Wake up the parent if it is waiting so that it can