5 files changed, 35 insertions, 3 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 856eac3ec52e..b7e9d60a675d 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -300,7 +300,7 @@ out:
 #ifdef CONFIG_MMU
 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
 {
-        struct vm_area_struct *mpnt, *tmp, **pprev;
+        struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
         struct rb_node **rb_link, *rb_parent;
         int retval;
         unsigned long charge;
@@ -328,6 +328,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
         if (retval)
                 goto out;
 
+        prev = NULL;
         for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
                 struct file *file;
 
@@ -359,7 +360,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
                         goto fail_nomem_anon_vma_fork;
                 tmp->vm_flags &= ~VM_LOCKED;
                 tmp->vm_mm = mm;
-                tmp->vm_next = NULL;
+                tmp->vm_next = tmp->vm_prev = NULL;
                 file = tmp->vm_file;
                 if (file) {
                         struct inode *inode = file->f_path.dentry->d_inode;
@@ -392,6 +393,8 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
                  */
                 *pprev = tmp;
                 pprev = &tmp->vm_next;
+                tmp->vm_prev = prev;
+                prev = tmp;
 
                 __vma_link_rb(mm, tmp, rb_link, rb_parent);
                 rb_link = &tmp->vm_rb.rb_right;
diff --git a/kernel/kfifo.c b/kernel/kfifo.c
index 4502604ecadf..6b5580c57644 100644
--- a/kernel/kfifo.c
+++ b/kernel/kfifo.c
@@ -503,6 +503,15 @@ unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
 }
 EXPORT_SYMBOL(__kfifo_out_r);
 
+void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
+{
+        unsigned int n;
+
+        n = __kfifo_peek_n(fifo, recsize);
+        fifo->out += n + recsize;
+}
+EXPORT_SYMBOL(__kfifo_skip_r);
+
 int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
         unsigned long len, unsigned int *copied, size_t recsize)
 {
diff --git a/kernel/sched.c b/kernel/sched.c
index 41541d79e3c8..09b574e7f4df 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3865,8 +3865,16 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
                 /*
                  * Owner changed, break to re-assess state.
                  */
-                if (lock->owner != owner)
+                if (lock->owner != owner) {
+                        /*
+                         * If the lock has switched to a different owner,
+                         * we likely have heavy contention. Return 0 to quit
+                         * optimistic spinning and not contend further:
+                         */
+                        if (lock->owner)
+                                return 0;
                         break;
+                }
 
                 /*
                  * Is that owner really running on that cpu?
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 613bc1f04610..0d53c8e853b1 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -206,6 +206,9 @@ void watchdog_overflow_callback(struct perf_event *event, int nmi,
                  struct perf_sample_data *data,
                  struct pt_regs *regs)
 {
+        /* Ensure the watchdog never gets throttled */
+        event->hw.interrupts = 0;
+
         if (__get_cpu_var(watchdog_nmi_touch) == true) {
                 __get_cpu_var(watchdog_nmi_touch) = false;
                 return;
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 2994a0e3a61c..8bd600c020e5 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -35,6 +35,9 @@
 #include <linux/lockdep.h>
 #include <linux/idr.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/workqueue.h>
+
 #include "workqueue_sched.h"
 
 enum {
@@ -1790,7 +1793,13 @@ static void process_one_work(struct worker *worker, struct work_struct *work)
         work_clear_pending(work);
         lock_map_acquire(&cwq->wq->lockdep_map);
         lock_map_acquire(&lockdep_map);
+        trace_workqueue_execute_start(work);
         f(work);
+        /*
+         * While we must be careful to not use "work" after this, the trace
+         * point will only record its address.
+         */
+        trace_workqueue_execute_end(work);
         lock_map_release(&lockdep_map);
         lock_map_release(&cwq->wq->lockdep_map);