10 files changed, 79 insertions, 51 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 91d5c38eb7e5..d1c6d152da89 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -376,9 +376,6 @@ void __weak arch_smt_update(void) { }
 
 #ifdef CONFIG_HOTPLUG_SMT
 enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED;
-EXPORT_SYMBOL_GPL(cpu_smt_control);
-
-static bool cpu_smt_available __read_mostly;
 
 void __init cpu_smt_disable(bool force)
 {
@@ -397,25 +394,11 @@ void __init cpu_smt_disable(bool force)
 
 /*
  * The decision whether SMT is supported can only be done after the full
- * CPU identification. Called from architecture code before non boot CPUs
- * are brought up.
- */
-void __init cpu_smt_check_topology_early(void)
-{
-        if (!topology_smt_supported())
-                cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
-}
-
-/*
- * If SMT was disabled by BIOS, detect it here, after the CPUs have been
- * brought online. This ensures the smt/l1tf sysfs entries are consistent
- * with reality. cpu_smt_available is set to true during the bringup of non
- * boot CPUs when a SMT sibling is detected. Note, this may overwrite
- * cpu_smt_control's previous setting.
+ * CPU identification. Called from architecture code.
  */
 void __init cpu_smt_check_topology(void)
 {
-        if (!cpu_smt_available)
+        if (!topology_smt_supported())
                 cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
 }
 
@@ -428,18 +411,10 @@ early_param("nosmt", smt_cmdline_disable);
 
 static inline bool cpu_smt_allowed(unsigned int cpu)
 {
-        if (topology_is_primary_thread(cpu))
+        if (cpu_smt_control == CPU_SMT_ENABLED)
                 return true;
 
-        /*
-         * If the CPU is not a 'primary' thread and the booted_once bit is
-         * set then the processor has SMT support. Store this information
-         * for the late check of SMT support in cpu_smt_check_topology().
-         */
-        if (per_cpu(cpuhp_state, cpu).booted_once)
-                cpu_smt_available = true;
-
-        if (cpu_smt_control == CPU_SMT_ENABLED)
+        if (topology_is_primary_thread(cpu))
                 return true;
 
         /*
@@ -2090,10 +2065,8 @@ static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
                  */
                 cpuhp_offline_cpu_device(cpu);
         }
-        if (!ret) {
+        if (!ret)
                 cpu_smt_control = ctrlval;
-                arch_smt_update();
-        }
         cpu_maps_update_done();
         return ret;
 }
@@ -2104,7 +2077,6 @@ static int cpuhp_smt_enable(void)
 
         cpu_maps_update_begin();
         cpu_smt_control = CPU_SMT_ENABLED;
-        arch_smt_update();
         for_each_present_cpu(cpu) {
                 /* Skip online CPUs and CPUs on offline nodes */
                 if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 3cd13a30f732..e5ede6918050 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -436,18 +436,18 @@ int perf_proc_update_handler(struct ctl_table *table, int write,
                 void __user *buffer, size_t *lenp,
                 loff_t *ppos)
 {
-        int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-
-        if (ret || !write)
-                return ret;
-
+        int ret;
+        int perf_cpu = sysctl_perf_cpu_time_max_percent;
         /*
          * If throttling is disabled don't allow the write:
          */
-        if (sysctl_perf_cpu_time_max_percent == 100 ||
-            sysctl_perf_cpu_time_max_percent == 0)
+        if (write && (perf_cpu == 100 || perf_cpu == 0))
                 return -EINVAL;
 
+        ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+        if (ret || !write)
+                return ret;
+
         max_samples_per_tick = DIV_ROUND_UP(sysctl_perf_event_sample_rate, HZ);
         perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
         update_perf_cpu_limits();
diff --git a/kernel/exit.c b/kernel/exit.c
index 3fb7be001964..2639a30a8aa5 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -558,12 +558,14 @@ static struct task_struct *find_alive_thread(struct task_struct *p)
         return NULL;
 }
 
-static struct task_struct *find_child_reaper(struct task_struct *father)
+static struct task_struct *find_child_reaper(struct task_struct *father,
+                                                struct list_head *dead)
         __releases(&tasklist_lock)
         __acquires(&tasklist_lock)
 {
         struct pid_namespace *pid_ns = task_active_pid_ns(father);
         struct task_struct *reaper = pid_ns->child_reaper;
+        struct task_struct *p, *n;
 
         if (likely(reaper != father))
                 return reaper;
@@ -579,6 +581,12 @@ static struct task_struct *find_child_reaper(struct task_struct *father)
                 panic("Attempted to kill init! exitcode=0x%08x\n",
                         father->signal->group_exit_code ?: father->exit_code);
         }
+
+        list_for_each_entry_safe(p, n, dead, ptrace_entry) {
+                list_del_init(&p->ptrace_entry);
+                release_task(p);
+        }
+
         zap_pid_ns_processes(pid_ns);
         write_lock_irq(&tasklist_lock);
 
@@ -668,7 +676,7 @@ static void forget_original_parent(struct task_struct *father,
                 exit_ptrace(father, dead);
 
         /* Can drop and reacquire tasklist_lock */
-        reaper = find_child_reaper(father);
+        reaper = find_child_reaper(father, dead);
         if (list_empty(&father->children))
                 return;
 
diff --git a/kernel/relay.c b/kernel/relay.c
index 04f248644e06..9e0f52375487 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -428,6 +428,8 @@ static struct dentry *relay_create_buf_file(struct rchan *chan,
         dentry = chan->cb->create_buf_file(tmpname, chan->parent,
                                            S_IRUSR, buf,
                                            &chan->is_global);
+        if (IS_ERR(dentry))
+                dentry = NULL;
 
         kfree(tmpname);
 
@@ -461,7 +463,7 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
                 dentry = chan->cb->create_buf_file(NULL, NULL,
                                                    S_IRUSR, buf,
                                                    &chan->is_global);
-                if (WARN_ON(dentry))
+                if (IS_ERR_OR_NULL(dentry))
                         goto free_buf;
         }
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 50aa2aba69bd..310d0637fe4b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5980,6 +5980,7 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p
 
 #ifdef CONFIG_SCHED_SMT
 DEFINE_STATIC_KEY_FALSE(sched_smt_present);
+EXPORT_SYMBOL_GPL(sched_smt_present);
 
 static inline void set_idle_cores(int cpu, int val)
 {
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index fe24de3fbc93..c3484785b179 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -124,6 +124,7 @@
  * sampling of the aggregate task states would be.
  */
 
+#include "../workqueue_internal.h"
 #include <linux/sched/loadavg.h>
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
@@ -480,9 +481,6 @@ static void psi_group_change(struct psi_group *group, int cpu,
                         groupc->tasks[t]++;
 
         write_seqcount_end(&groupc->seq);
-
-        if (!delayed_work_pending(&group->clock_work))
-                schedule_delayed_work(&group->clock_work, PSI_FREQ);
 }
 
 static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
@@ -513,6 +511,7 @@ void psi_task_change(struct task_struct *task, int clear, int set)
 {
         int cpu = task_cpu(task);
         struct psi_group *group;
+        bool wake_clock = true;
         void *iter = NULL;
 
         if (!task->pid)
@@ -530,8 +529,22 @@ void psi_task_change(struct task_struct *task, int clear, int set)
         task->psi_flags &= ~clear;
         task->psi_flags |= set;
 
-        while ((group = iterate_groups(task, &iter)))
+        /*
+         * Periodic aggregation shuts off if there is a period of no
+         * task changes, so we wake it back up if necessary. However,
+         * don't do this if the task change is the aggregation worker
+         * itself going to sleep, or we'll ping-pong forever.
+         */
+        if (unlikely((clear & TSK_RUNNING) &&
+                     (task->flags & PF_WQ_WORKER) &&
+                     wq_worker_last_func(task) == psi_update_work))
+                wake_clock = false;
+
+        while ((group = iterate_groups(task, &iter))) {
                 psi_group_change(group, cpu, clear, set);
+                if (wake_clock && !delayed_work_pending(&group->clock_work))
+                        schedule_delayed_work(&group->clock_work, PSI_FREQ);
+        }
 }
 
 void psi_memstall_tick(struct task_struct *task, int cpu)
diff --git a/kernel/smp.c b/kernel/smp.c
index 163c451af42e..f4cf1b0bb3b8 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -584,8 +584,6 @@ void __init smp_init(void)
                 num_nodes, (num_nodes > 1 ? "s" : ""),
                 num_cpus,  (num_cpus  > 1 ? "s" : ""));
 
-        /* Final decision about SMT support */
-        cpu_smt_check_topology();
         /* Any cleanup work */
         smp_cpus_done(setup_max_cpus);
 }
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index e335576b9411..9bde07c06362 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -5,7 +5,7 @@
  * Copyright (C) IBM Corporation, 2010-2012
  * Author:      Srikar Dronamraju <srikar@linux.vnet.ibm.com>
  */
-#define pr_fmt(fmt)     "trace_kprobe: " fmt
+#define pr_fmt(fmt)     "trace_uprobe: " fmt
 
 #include <linux/ctype.h>
 #include <linux/module.h>
@@ -160,6 +160,13 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
         if (ret >= 0) {
                 if (ret == maxlen)
                         dst[ret - 1] = '\0';
+                else
+                        /*
+                         * Include the terminating null byte. In this case it
+                         * was copied by strncpy_from_user but not accounted
+                         * for in ret.
+                         */
+                        ret++;
                 *(u32 *)dest = make_data_loc(ret, (void *)dst - base);
         }
 
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 392be4b252f6..fc5d23d752a5 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -910,6 +910,26 @@ struct task_struct *wq_worker_sleeping(struct task_struct *task)
 }
 
 /**
+ * wq_worker_last_func - retrieve worker's last work function
+ *
+ * Determine the last function a worker executed. This is called from
+ * the scheduler to get a worker's last known identity.
+ *
+ * CONTEXT:
+ * spin_lock_irq(rq->lock)
+ *
+ * Return:
+ * The last work function %current executed as a worker, NULL if it
+ * hasn't executed any work yet.
+ */
+work_func_t wq_worker_last_func(struct task_struct *task)
+{
+        struct worker *worker = kthread_data(task);
+
+        return worker->last_func;
+}
+
+/**
  * worker_set_flags - set worker flags and adjust nr_running accordingly
  * @worker: self
  * @flags: flags to set
@@ -2184,6 +2204,9 @@ __acquires(&pool->lock)
         if (unlikely(cpu_intensive))
                 worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
 
+        /* tag the worker for identification in schedule() */
+        worker->last_func = worker->current_func;
+
         /* we're done with it, release */
         hash_del(&worker->hentry);
         worker->current_work = NULL;
diff --git a/kernel/workqueue_internal.h b/kernel/workqueue_internal.h
index 66fbb5a9e633..cb68b03ca89a 100644
--- a/kernel/workqueue_internal.h
+++ b/kernel/workqueue_internal.h
@@ -53,6 +53,9 @@ struct worker {
 
         /* used only by rescuers to point to the target workqueue */
         struct workqueue_struct *rescue_wq;     /* I: the workqueue to rescue */
+
+        /* used by the scheduler to determine a worker's last known identity */
+        work_func_t             last_func;
 };
 
 /**
@@ -67,9 +70,10 @@ static inline struct worker *current_wq_worker(void)
 
 /*
  * Scheduler hooks for concurrency managed workqueue.  Only to be used from
- * sched/core.c and workqueue.c.
+ * sched/ and workqueue.c.
  */
 void wq_worker_waking_up(struct task_struct *task, int cpu);
 struct task_struct *wq_worker_sleeping(struct task_struct *task);
+work_func_t wq_worker_last_func(struct task_struct *task);
 
 #endif /* _KERNEL_WORKQUEUE_INTERNAL_H */