Patch "rcu: Fix missing TICK_DEP_MASK_RCU_EXP dependency check" has been added to the 6.3-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    rcu: Fix missing TICK_DEP_MASK_RCU_EXP dependency check

to the 6.3-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-fix-missing-tick_dep_mask_rcu_exp-dependency-che.patch
and it can be found in the queue-6.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 8b9c669f90b883b34886ef9f6c22fe78bb9ae86d
Author: Zqiang <qiang1.zhang@xxxxxxxxx>
Date:   Tue Dec 20 22:16:25 2022 +0800

    rcu: Fix missing TICK_DEP_MASK_RCU_EXP dependency check
    
    [ Upstream commit db7b464df9d820186e98a65aa6a10f0d51fbf8ce ]
    
    This commit adds checks for the TICK_DEP_MASK_RCU_EXP bit, thus enabling
    RCU expedited grace periods to actually force-enable scheduling-clock
    interrupts on holdout CPUs.
    
    Fixes: df1e849ae455 ("rcu: Enable tick for nohz_full CPUs slow to provide expedited QS")
    Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
    Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
    Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
    Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
    Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
    Cc: Ingo Molnar <mingo@xxxxxxxxxx>
    Cc: Anna-Maria Behnsen <anna-maria@xxxxxxxxxxxxx>
    Acked-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
    Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
    Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index 2e713a7d9aa3a..3e8619c72f774 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -371,7 +371,8 @@ TRACE_EVENT(itimer_expire,
 		tick_dep_name(PERF_EVENTS)		\
 		tick_dep_name(SCHED)			\
 		tick_dep_name(CLOCK_UNSTABLE)		\
-		tick_dep_name_end(RCU)
+		tick_dep_name(RCU)			\
+		tick_dep_name_end(RCU_EXP)
 
 #undef tick_dep_name
 #undef tick_dep_mask_name
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 68d81a4283c89..a46506f7ec6d0 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -281,6 +281,11 @@ static bool check_tick_dependency(atomic_t *dep)
 		return true;
 	}
 
+	if (val & TICK_DEP_MASK_RCU_EXP) {
+		trace_tick_stop(0, TICK_DEP_MASK_RCU_EXP);
+		return true;
+	}
+
 	return false;
 }