FAILED: patch "[PATCH] cpuidle: governors: menu: Select polling state in some more" failed to apply to 6.6-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x db86f55bf81a3a297be05ee8775ae9a8c6e3a599
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025110245-mongoose-ravioli-e19d@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From db86f55bf81a3a297be05ee8775ae9a8c6e3a599 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Thu, 23 Oct 2025 19:12:57 +0200
Subject: [PATCH] cpuidle: governors: menu: Select polling state in some more
 cases

A throughput regression of 11% introduced by commit 779b1a1cb13a ("cpuidle:
governors: menu: Avoid selecting states with too much latency") has been
reported and it is related to the case when the menu governor checks if
selecting a proper idle state instead of a polling one makes sense.

In particular, it is questionable to do so if the exit latency of the
idle state in question exceeds the predicted idle duration, so add a
check for that, which is sufficient to make the reported regression go
away, and update the related code comment accordingly.

Fixes: 779b1a1cb13a ("cpuidle: governors: menu: Avoid selecting states with too much latency")
Closes: https://lore.kernel.org/linux-pm/004501dc43c9$ec8aa930$c59ffb90$@telus.net/
Reported-by: Doug Smythies <dsmythies@telus.net>
Tested-by: Doug Smythies <dsmythies@telus.net>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/12786727.O9o76ZdvQC@rafael.j.wysocki

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 7d21fb5a72f4..23239b0c04f9 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -318,10 +318,13 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 
 		/*
 		 * Use a physical idle state, not busy polling, unless a timer
-		 * is going to trigger soon enough.
+		 * is going to trigger soon enough or the exit latency of the
+		 * idle state in question is greater than the predicted idle
+		 * duration.
 		 */
 		if ((drv->states[idx].flags & CPUIDLE_FLAG_POLLING) &&
-		    s->target_residency_ns <= data->next_timer_ns) {
+		    s->target_residency_ns <= data->next_timer_ns &&
+		    s->exit_latency_ns <= predicted_ns) {
 			predicted_ns = s->target_residency_ns;
 			idx = i;
 			break;