This is a note to let you know that I've just added the patch titled
rcu: Pull deferred rcuog wake up to rcu_eqs_enter() callers
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rcu-pull-deferred-rcuog-wake-up-to-rcu_eqs_enter-callers.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 54b7429efffc99e845ba9381bee3244f012a06c2 Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <frederic@xxxxxxxxxx>
Date: Mon, 1 Feb 2021 00:05:44 +0100
Subject: rcu: Pull deferred rcuog wake up to rcu_eqs_enter() callers
From: Frederic Weisbecker <frederic@xxxxxxxxxx>
commit 54b7429efffc99e845ba9381bee3244f012a06c2 upstream.
Deferred wakeup of rcuog kthreads upon RCU idle mode entry is going to
be handled differently whether initiated by idle, user or guest. Prepare
with pulling that control up to rcu_eqs_enter() callers.
Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20210131230548.32970-2-frederic@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -579,7 +579,6 @@ static void rcu_eqs_enter(bool user)
trace_rcu_dyntick(TPS("Start"), rdp->dynticks_nesting, 0, atomic_read(&rdp->dynticks));
WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
rdp = this_cpu_ptr(&rcu_data);
- do_nocb_deferred_wakeup(rdp);
rcu_prepare_for_idle();
rcu_preempt_deferred_qs(current);
WRITE_ONCE(rdp->dynticks_nesting, 0); /* Avoid irq-access tearing. */
@@ -600,7 +599,10 @@ static void rcu_eqs_enter(bool user)
*/
void rcu_idle_enter(void)
{
+ struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+
lockdep_assert_irqs_disabled();
+ do_nocb_deferred_wakeup(rdp);
rcu_eqs_enter(false);
}
@@ -618,7 +620,14 @@ void rcu_idle_enter(void)
*/
void rcu_user_enter(void)
{
+ struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
+
lockdep_assert_irqs_disabled();
+
+ instrumentation_begin();
+ do_nocb_deferred_wakeup(rdp);
+ instrumentation_end();
+
rcu_eqs_enter(true);
}
#endif /* CONFIG_NO_HZ_FULL */
Patches currently in stable-queue which might be from frederic@xxxxxxxxxx are
queue-5.4/rcu-nocb-perform-deferred-wake-up-before-last-idle-s-need_resched-check.patch
queue-5.4/rcu-nocb-trigger-self-ipi-on-late-deferred-wake-up-before-user-resume.patch
queue-5.4/rcu-pull-deferred-rcuog-wake-up-to-rcu_eqs_enter-callers.patch
