FAILED: patch "[PATCH] PM: EM: Fix late boot with holes in CPU topology" failed to apply to 6.12-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.12-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-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 1ebe8f7e782523e62cd1fa8237f7afba5d1dae83
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025101616-gigahertz-profane-b22c@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From 1ebe8f7e782523e62cd1fa8237f7afba5d1dae83 Mon Sep 17 00:00:00 2001
From: Christian Loehle <christian.loehle@arm.com>
Date: Sun, 31 Aug 2025 22:43:57 +0100
Subject: [PATCH] PM: EM: Fix late boot with holes in CPU topology

Commit e3f1164fc9ee ("PM: EM: Support late CPUs booting and capacity
adjustment") added a mechanism to handle CPUs that come up late by
retrying when any of the `cpufreq_cpu_get()` call fails.

However, if there are holes in the CPU topology (offline CPUs, e.g.
nosmt), the first missing CPU causes the loop to break, preventing
subsequent online CPUs from being updated.

Instead of aborting on the first missing CPU policy, loop through all
and retry if any were missing.

Fixes: e3f1164fc9ee ("PM: EM: Support late CPUs booting and capacity adjustment")
Suggested-by: Kenneth Crudup <kenneth.crudup@gmail.com>
Reported-by: Kenneth Crudup <kenneth.crudup@gmail.com>
Link: https://lore.kernel.org/linux-pm/40212796-734c-4140-8a85-854f72b8144d@panix.com/
Cc: 6.9+ <stable@vger.kernel.org> # 6.9+
Signed-off-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/20250831214357.2020076-1-christian.loehle@arm.com
[ rjw: Drop the new pr_debug() message which is not very useful ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index 8df55397414a..5f17d2e8e954 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -799,7 +799,7 @@ void em_adjust_cpu_capacity(unsigned int cpu)
 static void em_check_capacity_update(void)
 {
 	cpumask_var_t cpu_done_mask;
-	int cpu;
+	int cpu, failed_cpus = 0;
 
 	if (!zalloc_cpumask_var(&cpu_done_mask, GFP_KERNEL)) {
 		pr_warn("no free memory\n");
@@ -817,10 +817,8 @@ static void em_check_capacity_update(void)
 
 		policy = cpufreq_cpu_get(cpu);
 		if (!policy) {
-			pr_debug("Accessing cpu%d policy failed\n", cpu);
-			schedule_delayed_work(&em_update_work,
-					      msecs_to_jiffies(1000));
-			break;
+			failed_cpus++;
+			continue;
 		}
 		cpufreq_cpu_put(policy);
 
@@ -835,6 +833,9 @@ static void em_check_capacity_update(void)
 		em_adjust_new_capacity(cpu, dev, pd);
 	}
 
+	if (failed_cpus)
+		schedule_delayed_work(&em_update_work, msecs_to_jiffies(1000));
+
 	free_cpumask_var(cpu_done_mask);
 }