Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core updates (RCU and locking) from Ingo Molnar:
 "Most of the diffstat comes from the RCU slow boot regression fixes,
  but there's also a debuggability improvements/fixes."

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  memblock: Document memblock_is_region_{memory,reserved}()
  rcu: Precompute RCU_FAST_NO_HZ timer offsets
  rcu: Move RCU_FAST_NO_HZ per-CPU variables to rcu_dynticks structure
  rcu: Update RCU_FAST_NO_HZ tracing for lazy callbacks
  rcu: RCU_FAST_NO_HZ detection of callback adoption
  spinlock: Indicate that a lockup is only suspected
  kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop()
  panic: Make panic_on_oops configurable

11 files changed, 160 insertions, 85 deletions

diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index adb5e5a38cae..854dc4c5c271 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -87,8 +87,9 @@ static inline void kfree_call_rcu(struct rcu_head *head,
 
 #ifdef CONFIG_TINY_RCU
 
-static inline int rcu_needs_cpu(int cpu)
+static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
 {
+        *delta_jiffies = ULONG_MAX;
         return 0;
 }
 
@@ -96,8 +97,9 @@ static inline int rcu_needs_cpu(int cpu)
 
 int rcu_preempt_needs_cpu(void);
 
-static inline int rcu_needs_cpu(int cpu)
+static inline int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
 {
+        *delta_jiffies = ULONG_MAX;
         return rcu_preempt_needs_cpu();
 }
 
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 3c6083cde4fc..952b79339304 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -32,7 +32,7 @@
 
 extern void rcu_init(void);
 extern void rcu_note_context_switch(int cpu);
-extern int rcu_needs_cpu(int cpu);
+extern int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies);
 extern void rcu_cpu_stall_reset(void);
 
 /*
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 1480900c511c..d274734b2aa4 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -289,6 +289,7 @@ TRACE_EVENT(rcu_dyntick,
  *      "In holdoff": Nothing to do, holding off after unsuccessful attempt.
  *      "Begin holdoff": Attempt failed, don't retry until next jiffy.
  *      "Dyntick with callbacks": Entering dyntick-idle despite callbacks.
+ *      "Dyntick with lazy callbacks": Entering dyntick-idle w/lazy callbacks.
  *      "More callbacks": Still more callbacks, try again to clear them out.
  *      "Callbacks drained": All callbacks processed, off to dyntick idle!
  *      "Timer": Timer fired to cause CPU to continue processing callbacks.
diff --git a/kernel/panic.c b/kernel/panic.c
index 8ed89a175d79..d2a5f4ecc6dd 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -27,7 +27,7 @@
 #define PANIC_TIMER_STEP 100
 #define PANIC_BLINK_SPD 18
 
-int panic_on_oops;
+int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
 static unsigned long tainted_mask;
 static int pause_on_oops;
 static int pause_on_oops_flag;
@@ -108,8 +108,6 @@ void panic(const char *fmt, ...)
          */
         crash_kexec(NULL);
 
-        kmsg_dump(KMSG_DUMP_PANIC);
-
         /*
          * Note smp_send_stop is the usual smp shutdown function, which
          * unfortunately means it may not be hardened to work in a panic
@@ -117,6 +115,8 @@ void panic(const char *fmt, ...)
          */
         smp_send_stop();
 
+        kmsg_dump(KMSG_DUMP_PANIC);
+
         atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
         bust_spinlocks(0);
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 0da7b88d92d0..3b0f1337f75b 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1397,6 +1397,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
         rdp->qlen_lazy += rsp->qlen_lazy;
         rdp->qlen += rsp->qlen;
         rdp->n_cbs_adopted += rsp->qlen;
+        if (rsp->qlen_lazy != rsp->qlen)
+                rcu_idle_count_callbacks_posted();
         rsp->qlen_lazy = 0;
         rsp->qlen = 0;
 
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 7f5d138dedf5..ea056495783e 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -84,6 +84,20 @@ struct rcu_dynticks {
                                     /* Process level is worth LLONG_MAX/2. */
         int dynticks_nmi_nesting;   /* Track NMI nesting level. */
         atomic_t dynticks;          /* Even value for idle, else odd. */
+#ifdef CONFIG_RCU_FAST_NO_HZ
+        int dyntick_drain;          /* Prepare-for-idle state variable. */
+        unsigned long dyntick_holdoff;
+                                    /* No retries for the jiffy of failure. */
+        struct timer_list idle_gp_timer;
+                                    /* Wake up CPU sleeping with callbacks. */
+        unsigned long idle_gp_timer_expires;
+                                    /* When to wake up CPU (for repost). */
+        bool idle_first_pass;       /* First pass of attempt to go idle? */
+        unsigned long nonlazy_posted;
+                                    /* # times non-lazy CBs posted to CPU. */
+        unsigned long nonlazy_posted_snap;
+                                    /* idle-period nonlazy_posted snapshot. */
+#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
 };
 
 /* RCU's kthread states for tracing. */
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 2411000d9869..5271a020887e 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -1886,8 +1886,9 @@ static void __cpuinit rcu_prepare_kthreads(int cpu)
  * Because we not have RCU_FAST_NO_HZ, just check whether this CPU needs
  * any flavor of RCU.
  */
-int rcu_needs_cpu(int cpu)
+int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies)
 {
+        *delta_jiffies = ULONG_MAX;
         return rcu_cpu_has_callbacks(cpu);
 }
 
@@ -1962,41 +1963,6 @@ static void rcu_idle_count_callbacks_posted(void)
 #define RCU_IDLE_GP_DELAY 6             /* Roughly one grace period. */
 #define RCU_IDLE_LAZY_GP_DELAY (6 * HZ) /* Roughly six seconds. */
 
-/* Loop counter for rcu_prepare_for_idle(). */
-static DEFINE_PER_CPU(int, rcu_dyntick_drain);
-/* If rcu_dyntick_holdoff==jiffies, don't try to enter dyntick-idle mode. */
-static DEFINE_PER_CPU(unsigned long, rcu_dyntick_holdoff);
-/* Timer to awaken the CPU if it enters dyntick-idle mode with callbacks. */
-static DEFINE_PER_CPU(struct timer_list, rcu_idle_gp_timer);
-/* Scheduled expiry time for rcu_idle_gp_timer to allow reposting. */
-static DEFINE_PER_CPU(unsigned long, rcu_idle_gp_timer_expires);
-/* Enable special processing on first attempt to enter dyntick-idle mode. */
-static DEFINE_PER_CPU(bool, rcu_idle_first_pass);
-/* Running count of non-lazy callbacks posted, never decremented. */
-static DEFINE_PER_CPU(unsigned long, rcu_nonlazy_posted);
-/* Snapshot of rcu_nonlazy_posted to detect meaningful exits from idle. */
-static DEFINE_PER_CPU(unsigned long, rcu_nonlazy_posted_snap);
-
-/*
- * Allow the CPU to enter dyntick-idle mode if either: (1) There are no
- * callbacks on this CPU, (2) this CPU has not yet attempted to enter
- * dyntick-idle mode, or (3) this CPU is in the process of attempting to
- * enter dyntick-idle mode.  Otherwise, if we have recently tried and failed
- * to enter dyntick-idle mode, we refuse to try to enter it.  After all,
- * it is better to incur scheduling-clock interrupts than to spin
- * continuously for the same time duration!
- */
-int rcu_needs_cpu(int cpu)
-{
-        /* Flag a new idle sojourn to the idle-entry state machine. */
-        per_cpu(rcu_idle_first_pass, cpu) = 1;