7 files changed, 54 insertions, 20 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index d0b7d988f873..e6e01b959a0e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1540,8 +1540,15 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
         }
 
         /* dead body doesn't have much to contribute */
-        if (p->exit_state == EXIT_DEAD)
+        if (unlikely(p->exit_state == EXIT_DEAD)) {
+                /*
+                 * But do not ignore this task until the tracer does
+                 * wait_task_zombie()->do_notify_parent().
+                 */
+                if (likely(!ptrace) && unlikely(ptrace_reparented(p)))
+                        wo->notask_error = 0;
                 return 0;
+        }
 
         /* slay zombie? */
         if (p->exit_state == EXIT_ZOMBIE) {
diff --git a/kernel/futex.c b/kernel/futex.c
index ea87f4d2f455..1614be20173d 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -314,17 +314,29 @@ again:
 #endif
 
         lock_page(page_head);
+
+        /*
+         * If page_head->mapping is NULL, then it cannot be a PageAnon
+         * page; but it might be the ZERO_PAGE or in the gate area or
+         * in a special mapping (all cases which we are happy to fail);
+         * or it may have been a good file page when get_user_pages_fast
+         * found it, but truncated or holepunched or subjected to
+         * invalidate_complete_page2 before we got the page lock (also
+         * cases which we are happy to fail).  And we hold a reference,
+         * so refcount care in invalidate_complete_page's remove_mapping
+         * prevents drop_caches from setting mapping to NULL beneath us.
+         *
+         * The case we do have to guard against is when memory pressure made
+         * shmem_writepage move it from filecache to swapcache beneath us:
+         * an unlikely race, but we do need to retry for page_head->mapping.
+         */
         if (!page_head->mapping) {
+                int shmem_swizzled = PageSwapCache(page_head);
                 unlock_page(page_head);
                 put_page(page_head);
-                /*
-                * ZERO_PAGE pages don't have a mapping. Avoid a busy loop
-                * trying to find one. RW mapping would have COW'd (and thus
-                * have a mapping) so this page is RO and won't ever change.
-                */
-                if ((page_head == ZERO_PAGE(address)))
-                        return -EFAULT;
-                goto again;
+                if (shmem_swizzled)
+                        goto again;
+                return -EFAULT;
         }
 
         /*
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 8b1748d0172c..2e48ec0c2e91 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -74,11 +74,17 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 
         /*
          * Ensure the task is not frozen.
-         * Also, when a freshly created task is scheduled once, changes
-         * its state to TASK_UNINTERRUPTIBLE without having ever been
-         * switched out once, it musn't be checked.
+         * Also, skip vfork and any other user process that freezer should skip.
          */
-        if (unlikely(t->flags & PF_FROZEN || !switch_count))
+        if (unlikely(t->flags & (PF_FROZEN | PF_FREEZER_SKIP)))
+            return;
+
+        /*
+         * When a freshly created task is scheduled once, changes its state to
+         * TASK_UNINTERRUPTIBLE without having ever been switched out once, it
+         * musn't be checked.
+         */
+        if (unlikely(!switch_count))
                 return;
 
         if (switch_count != t->last_switch_count) {
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 24d04477b257..78ab24a7b0e4 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -96,9 +96,20 @@ void __ptrace_unlink(struct task_struct *child)
          */
         if (!(child->flags & PF_EXITING) &&
             (child->signal->flags & SIGNAL_STOP_STOPPED ||
-             child->signal->group_stop_count))
+             child->signal->group_stop_count)) {
                 child->jobctl |= JOBCTL_STOP_PENDING;
 
+                /*
+                 * This is only possible if this thread was cloned by the
+                 * traced task running in the stopped group, set the signal
+                 * for the future reports.
+                 * FIXME: we should change ptrace_init_task() to handle this
+                 * case.
+                 */
+                if (!(child->jobctl & JOBCTL_STOP_SIGMASK))
+                        child->jobctl |= SIGSTOP;
+        }
+
         /*
          * If transition to TASK_STOPPED is pending or in TASK_TRACED, kick
          * @child in the butt.  Note that @resume should be used iff @child
diff --git a/kernel/signal.c b/kernel/signal.c
index b3f78d09a105..206551563cce 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1994,8 +1994,6 @@ static bool do_signal_stop(int signr)
                  */
                 if (!(sig->flags & SIGNAL_STOP_STOPPED))
                         sig->group_exit_code = signr;
-                else
-                        WARN_ON_ONCE(!current->ptrace);
 
                 sig->group_stop_count = 0;
 
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index c4eb71c8b2ea..1ecd6ba36d6c 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -387,7 +387,6 @@ void clockevents_exchange_device(struct clock_event_device *old,
          * released list and do a notify add later.
          */
         if (old) {
-                old->event_handler = clockevents_handle_noop;
                 clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
                 list_del(&old->list);
                 list_add(&old->list, &clockevents_released);
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index db110b8ae030..f1539decd99d 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -634,10 +634,11 @@ static int tracepoint_module_coming(struct module *mod)
         int ret = 0;
 
         /*
-         * We skip modules that tain the kernel, especially those with different
-         * module header (for forced load), to make sure we don't cause a crash.
+         * We skip modules that taint the kernel, especially those with different
+         * module headers (for forced load), to make sure we don't cause a crash.
+         * Staging and out-of-tree GPL modules are fine.
          */
-        if (mod->taints)
+        if (mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP)))
                 return 0;
         mutex_lock(&tracepoints_mutex);
         tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL);