From: Paul E. McKenney <paulmck@kernel.org>
Date: Thu, 6 Mar 2025 18:12:31 +0000 (-0800)
Subject: stop-machine: Add comment for rcu_momentary_eqs()
X-Git-Tag: v6.15-rc1~224^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2af8780d6c8addecda5a0f624c4f084a3a9578fe;p=thirdparty%2Flinux.git

stop-machine: Add comment for rcu_momentary_eqs()

Add a comment to explain the purpose of the rcu_momentary_eqs() call
from multi_cpu_stop(), which is to suppress false-positive RCU CPU
stall warnings.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/87wmeuanti.ffs@tglx/
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
---

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 8896d844d738f..5d2d0562115b3 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -250,6 +250,7 @@ static int multi_cpu_stop(void *data)
 			 * be detected and reported on their side.
 			 */
 			touch_nmi_watchdog();
+			/* Also suppress RCU CPU stall warnings. */
 			rcu_momentary_eqs();
 		}
 	} while (curstate != MULTI_STOP_EXIT);