Update to 5.17.3rc1-1

1 files changed, 119 insertions, 0 deletions

diff --git a/0005-tick-rcu-Stop-allowing-RCU_SOFTIRQ-in-idle.patch b/0005-tick-rcu-Stop-allowing-RCU_SOFTIRQ-in-idle.patch
new file mode 100644
index 000000000000..0c3f3a6a423b
--- /dev/null
+++ b/0005-tick-rcu-Stop-allowing-RCU_SOFTIRQ-in-idle.patch
@@ -0,0 +1,119 @@
+From 894c674f70127b8fe02878ada383f534a1c63beb Mon Sep 17 00:00:00 2001
+From: Frederic Weisbecker <frederic@kernel.org>
+Date: Tue, 8 Feb 2022 17:16:34 +0100
+Subject: [PATCH 5/9] tick/rcu: Stop allowing RCU_SOFTIRQ in idle
+
+RCU_SOFTIRQ used to be special in that it could be raised on purpose
+within the idle path to prevent from stopping the tick. Some code still
+prevents from unnecessary warnings related to this specific behaviour
+while entering in dynticks-idle mode.
+
+However the nohz layout has changed quite a bit in ten years, and the
+removal of CONFIG_RCU_FAST_NO_HZ has been the final straw to this
+safe-conduct. Now the RCU_SOFTIRQ vector is expected to be raised from
+sane places.
+
+A remaining corner case is admitted though when the vector is invoked
+in fragile hotplug path.
+
+Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
+Cc: Thomas Gleixner <tglx@linutronix.de>
+Cc: Peter Zijlstra <peterz@infradead.org>
+Cc: Paul E. McKenney <paulmck@kernel.org>
+Cc: Paul Menzel <pmenzel@molgen.mpg.de>
+---
+ include/linux/interrupt.h |  8 ++++++-
+ kernel/time/tick-sched.c  | 50 +++++++++++++++++++++++++++++++--------
+ 2 files changed, 47 insertions(+), 11 deletions(-)
+
+diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
+index 9367f1cb2e3c..9613326d2f8a 100644
+--- a/include/linux/interrupt.h
++++ b/include/linux/interrupt.h
+@@ -579,7 +579,13 @@ enum
+ 	NR_SOFTIRQS
+ };
+ 
+-#define SOFTIRQ_STOP_IDLE_MASK (~(1 << RCU_SOFTIRQ))
++/*
++ * Ignoring the RCU vector after ksoftirqd is parked is fine
++ * because:
++ * 	1) rcutree_migrate_callbacks() takes care of the queue.
++ * 	2) rcu_report_dead() reports the final quiescent states.
++ */
++#define SOFTIRQ_HOTPLUG_SAFE_MASK (BIT(RCU_SOFTIRQ))
+ 
+ /* map softirq index to softirq name. update 'softirq_to_name' in
+  * kernel/softirq.c when adding a new softirq.
+diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
+index 566ad5bd83e9..2d76c91b85de 100644
+--- a/kernel/time/tick-sched.c
++++ b/kernel/time/tick-sched.c
+@@ -999,6 +999,45 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts)
+ 	__tick_nohz_full_update_tick(ts, ktime_get());
+ }
+ 
++/*
++ * A pending softirq outside an IRQ (or softirq disabled section) context
++ * should be waiting for ksoftirqd to handle it. Therefore we shouldn't
++ * reach here due to the need_resched() early check in can_stop_idle_tick().
++ *
++ * However if we are between CPUHP_AP_SMPBOOT_THREADS and CPU_TEARDOWN_CPU on the
++ * cpu_down() process, softirqs can still be raised while ksoftirqd is parked,
++ * triggering the below since wakep_softirqd() is ignored.
++ *
++ */
++static bool report_idle_softirq(void)
++{
++	static int ratelimit;
++	unsigned int pending = local_softirq_pending();
++
++	if (likely(!pending))
++		return false;
++
++	/* Some softirqs claim to be safe against hotplug and ksoftirqd parking */
++	if (!cpu_active(smp_processor_id())) {
++		pending &= ~SOFTIRQ_HOTPLUG_SAFE_MASK;
++		if (!pending)
++			return false;
++	}
++
++	if (ratelimit < 10)
++		return false;
++
++	/* On RT, softirqs handling may be waiting on some lock */
++	if (!local_bh_blocked())
++		return false;
++
++	pr_warn("NOHZ tick-stop error: local softirq work is pending, handler #%02x!!!\n",
++		pending);
++	ratelimit++;
++
++	return true;
++}
++
+ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
+ {
+ 	/*
+@@ -1025,17 +1064,8 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
+ 	if (need_resched())
+ 		return false;
+ 
+-	if (unlikely(local_softirq_pending())) {
+-		static int ratelimit;
+-
+-		if (ratelimit < 10 && !local_bh_blocked() &&
+-		    (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) {
+-			pr_warn("NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #%02x!!!\n",
+-				(unsigned int) local_softirq_pending());
+-			ratelimit++;
+-		}
++	if (unlikely(report_idle_softirq()))
+ 		return false;
+-	}
+ 
+ 	if (tick_nohz_full_enabled()) {
+ 		/*
+-- 
+2.35.1
+