[ANNOUNCE] v5.17-rc7-rt13v5.17-rc7-rt13-patches

Dear RT folks!

I'm pleased to announce the v5.17-rc7-rt13 patch set.

Changes since v5.17-rc7-rt12:

  - Instead of spawning ksoftirqd early, adjust the RCU-tasks timeout
    after discussion with upstream.

Known issues
     - Valentin Schneider reported a few splats on ARM64, see
          https://lkml.kernel.org/r/20210810134127.1394269-1-valentin.schneider@arm.com

The delta patch against v5.17-rc7-rt12 is appended below and can be found here:

     https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.17/incr/patch-5.17-rc7-rt12-rt13.patch.xz

You can get this release via the git tree at:

    git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.17-rc7-rt13

The RT patch against v5.17-rc7 can be found here:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.17/older/patch-5.17-rc7-rt13.patch.xz

The split quilt queue is available at:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.17/older/patches-5.17-rc7-rt13.tar.xz

Sebastian

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

7 files changed, 55 insertions, 63 deletions

diff --git a/patches/Add_localversion_for_-RT_release.patch b/patches/Add_localversion_for_-RT_release.patch
index 7bc90935ffb7..7b0058411028 100644
--- a/patches/Add_localversion_for_-RT_release.patch
+++ b/patches/Add_localversion_for_-RT_release.patch
@@ -15,4 +15,4 @@ Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
 --- /dev/null
 +++ b/localversion-rt
 @@ -0,0 +1 @@
-+-rt12
++-rt13
diff --git a/patches/rcu-tasks-Use-schedule_hrtimeout_range-while-waiting.patch b/patches/rcu-tasks-Use-schedule_hrtimeout_range-while-waiting.patch
new file mode 100644
index 000000000000..df6bff82cc36
--- /dev/null
+++ b/patches/rcu-tasks-Use-schedule_hrtimeout_range-while-waiting.patch
@@ -0,0 +1,42 @@
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Mon, 7 Mar 2022 17:08:23 +0100
+Subject: [PATCH] rcu-tasks: Use schedule_hrtimeout_range() while waiting for
+ the gp.
+
+The RCU selftest is using schedule_timeout_idle() which fails on
+PREEMPT_RT because it is used early in boot-up phase an which point
+ksoftirqd is not yet ready and is required for the timer to expire.
+
+To avoid this lockup, use schedule_hrtimeout() and let the timer expire
+in hardirq context. This is ensures that the timer fires even on
+PREEMPT_RT without any further requirement.
+
+The timer is set to expire between fract and fract + HZ / 2 jiffies in
+order to minimize the amount of extra wake ups and to allign with
+possible other timer which expire within this window.
+
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ kernel/rcu/tasks.h |    7 +++++--
+ 1 file changed, 5 insertions(+), 2 deletions(-)
+
+--- a/kernel/rcu/tasks.h
++++ b/kernel/rcu/tasks.h
+@@ -630,12 +630,15 @@ static void rcu_tasks_wait_gp(struct rcu
+ 	while (!list_empty(&holdouts)) {
+ 		bool firstreport;
+ 		bool needreport;
++		ktime_t exp;
+ 		int rtst;
+ 
+ 		/* Slowly back off waiting for holdouts */
+ 		set_tasks_gp_state(rtp, RTGS_WAIT_SCAN_HOLDOUTS);
+-		schedule_timeout_idle(fract);
+-
++		exp = jiffies_to_nsecs(fract);
++		__set_current_state(TASK_IDLE);
++		schedule_hrtimeout_range(&exp, jiffies_to_nsecs(HZ / 2),
++					 HRTIMER_MODE_REL_HARD);
+ 		if (fract < HZ)
+ 			fract++;
+ 
diff --git a/patches/series b/patches/series
index 3d4df3c087ae..0220b2fadf6b 100644
--- a/patches/series
+++ b/patches/series
@@ -34,8 +34,10 @@ irq_poll-Use-raise_softirq_irqoff-in-cpu_dead-notifi.patch
 smp_wake_ksoftirqd_on_preempt_rt_instead_do_softirq.patch
 signal_x86__Delay_calling_signals_in_atomic.patch
 
-# net-next
-tcp-Don-t-acquire-inet_listen_hashbucket-lock-with-d.patch
+# misc
+drm-i915-Depend-on-PREEMPT_RT.patch
+cgroup__use_irqsave_in_cgroup_rstat_flush_locked.patch
+mm__workingset__replace_IRQ-off_check_with_a_lockdep_assert..patch
 
 # Random, backports from git.kernel.org/pub/scm/linux/kernel/git/crng/random.git
 # stashed for 5.18
@@ -50,6 +52,7 @@ tcp-Don-t-acquire-inet_listen_hashbucket-lock-with-d.patch
 random-Move-crng_fast_load-to-the-worker.patch
 
 # sched/fork, expecting in 5.18
+tcp-Don-t-acquire-inet_listen_hashbucket-lock-with-d.patch
 0001-kernel-fork-Redo-ifdefs-around-task-s-handling.patch
 0002-kernel-fork-Duplicate-task_struct-before-stack-alloc.patch
 0003-kernel-fork-IA64-Provide-a-alloc_thread_stack_node-f.patch
@@ -88,17 +91,14 @@ mm-memcg-Only-perform-the-debug-checks-on-PREEMPT_RT.patch
 ###########################################################################
 # Posted
 ###########################################################################
-drm-i915-Depend-on-PREEMPT_RT.patch
-cgroup__use_irqsave_in_cgroup_rstat_flush_locked.patch
-mm__workingset__replace_IRQ-off_check_with_a_lockdep_assert..patch
 x86-kvm-Require-const-tsc-for-RT.patch
 ptrace-fix-ptrace-vs-tasklist_lock-race-on-PREEMPT_R.patch
 rcu-tasks-Use-rcuwait-for-the-rcu_tasks_kthread.patch
+rcu-tasks-Use-schedule_hrtimeout_range-while-waiting.patch
 
 ###########################################################################
 # Post
 ###########################################################################
-softirq-Spawn-ksoftirqd-before-the-RCU-tests.patch
 
 ###########################################################################
 # sched:
diff --git a/patches/signal__Revert_ptrace_preempt_magic.patch b/patches/signal__Revert_ptrace_preempt_magic.patch
index 75ba96af04b9..38b67d2b8d67 100644
--- a/patches/signal__Revert_ptrace_preempt_magic.patch
+++ b/patches/signal__Revert_ptrace_preempt_magic.patch
@@ -17,7 +17,7 @@ Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
 ---
 --- a/kernel/signal.c
 +++ b/kernel/signal.c
-@@ -2304,16 +2304,8 @@ static void ptrace_stop(int exit_code, i
+@@ -2316,16 +2316,8 @@ static void ptrace_stop(int exit_code, i
  		if (gstop_done && ptrace_reparented(current))
  			do_notify_parent_cldstop(current, false, why);
  
diff --git a/patches/softirq-Spawn-ksoftirqd-before-the-RCU-tests.patch b/patches/softirq-Spawn-ksoftirqd-before-the-RCU-tests.patch
deleted file mode 100644
index d9ed4e1ba18f..000000000000
--- a/patches/softirq-Spawn-ksoftirqd-before-the-RCU-tests.patch
+++ /dev/null
@@ -1,50 +0,0 @@
-From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
-Date: Fri, 4 Mar 2022 11:41:30 +0100
-Subject: [PATCH] softirq: Spawn ksoftirqd before the RCU tests.
-
-Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
----
- include/linux/interrupt.h |    1 +
- init/main.c               |    1 +
- kernel/softirq.c          |    5 +----
- 3 files changed, 3 insertions(+), 4 deletions(-)
-
---- a/include/linux/interrupt.h
-+++ b/include/linux/interrupt.h
-@@ -600,6 +600,7 @@ asmlinkage void __do_softirq(void);
- 
- extern void open_softirq(int nr, void (*action)(struct softirq_action *));
- extern void softirq_init(void);
-+extern void softirq_spawn_ksoftirqd(void);
- extern void __raise_softirq_irqoff(unsigned int nr);
- 
- extern void raise_softirq_irqoff(unsigned int nr);
---- a/init/main.c
-+++ b/init/main.c
-@@ -1598,6 +1598,7 @@ static noinline void __init kernel_init_
- 
- 	init_mm_internals();
- 
-+	softirq_spawn_ksoftirqd();
- 	rcu_init_tasks_generic();
- 	do_pre_smp_initcalls();
- 	lockup_detector_init();
---- a/kernel/softirq.c
-+++ b/kernel/softirq.c
-@@ -963,15 +963,12 @@ static struct smp_hotplug_thread softirq
- 	.thread_comm		= "ksoftirqd/%u",
- };
- 
--static __init int spawn_ksoftirqd(void)
-+__init void softirq_spawn_ksoftirqd(void)
- {
- 	cpuhp_setup_state_nocalls(CPUHP_SOFTIRQ_DEAD, "softirq:dead", NULL,
- 				  takeover_tasklets);
- 	BUG_ON(smpboot_register_percpu_thread(&softirq_threads));
--
--	return 0;
- }
--early_initcall(spawn_ksoftirqd);
- 
- /*
-  * [ These __weak aliases are kept in a separate compilation unit, so that
diff --git a/patches/softirq-Use-a-dedicated-thread-for-timer-wakeups.patch b/patches/softirq-Use-a-dedicated-thread-for-timer-wakeups.patch
index fa2bd5b08b37..9a8405ae4dea 100644
--- a/patches/softirq-Use-a-dedicated-thread-for-timer-wakeups.patch
+++ b/patches/softirq-Use-a-dedicated-thread-for-timer-wakeups.patch
@@ -45,7 +45,7 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 
 --- a/include/linux/interrupt.h
 +++ b/include/linux/interrupt.h
-@@ -606,6 +606,22 @@ extern void __raise_softirq_irqoff(unsig
+@@ -605,6 +605,22 @@ extern void __raise_softirq_irqoff(unsig
  extern void raise_softirq_irqoff(unsigned int nr);
  extern void raise_softirq(unsigned int nr);
  
@@ -162,16 +162,16 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
 +        .thread_comm            = "ktimers/%u",
 +};
 +
- __init void softirq_spawn_ksoftirqd(void)
+ static __init int spawn_ksoftirqd(void)
  {
  	cpuhp_setup_state_nocalls(CPUHP_SOFTIRQ_DEAD, "softirq:dead", NULL,
  				  takeover_tasklets);
  	BUG_ON(smpboot_register_percpu_thread(&softirq_threads));
 +	if (IS_ENABLED(CONFIG_PREEMPT_RT))
 +		BUG_ON(smpboot_register_percpu_thread(&timer_threads));
- }
  
- /*
+ 	return 0;
+ }
 --- a/kernel/time/hrtimer.c
 +++ b/kernel/time/hrtimer.c
 @@ -1805,7 +1805,7 @@ void hrtimer_interrupt(struct clock_even
diff --git a/patches/x86_entry__Use_should_resched_in_idtentry_exit_cond_resched.patch b/patches/x86_entry__Use_should_resched_in_idtentry_exit_cond_resched.patch
index 77891603dc3c..89ba39cc46b1 100644
--- a/patches/x86_entry__Use_should_resched_in_idtentry_exit_cond_resched.patch
+++ b/patches/x86_entry__Use_should_resched_in_idtentry_exit_cond_resched.patch
@@ -21,7 +21,7 @@ Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
 ---
 --- a/kernel/entry/common.c
 +++ b/kernel/entry/common.c
-@@ -395,7 +395,7 @@ void irqentry_exit_cond_resched(void)
+@@ -401,7 +401,7 @@ void irqentry_exit_cond_resched(void)
  		rcu_irq_exit_check_preempt();
  		if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
  			WARN_ON_ONCE(!on_thread_stack());