Subject: FAILED: patch "[PATCH] platform/x86/intel-uncore-freq: Fix current_freq_khz after" failed to apply to 6.12-stable tree
To: weiguixiong@bytedance.com,ilpo.jarvinen@linux.intel.com,srinivas.pandruvada@linux.intel.com
Cc: <stable@vger.kernel.org>
From: <gregkh@linuxfoundation.org>
Date: Mon, 20 Jul 2026 17:03:30 +0200
Message-ID: <2026072029-algorithm-overbook-efa9@gregkh>
Precedence: bulk
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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 6b63520ed14b17bbe9c2103debbd2152dde1fba3
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026072029-algorithm-overbook-efa9@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..'

Possible dependencies:


thanks,

greg k-h

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

From 6b63520ed14b17bbe9c2103debbd2152dde1fba3 Mon Sep 17 00:00:00 2001
From: Guixiong Wei <weiguixiong@bytedance.com>
Date: Tue, 2 Jun 2026 10:07:52 +0800
Subject: [PATCH] platform/x86/intel-uncore-freq: Fix current_freq_khz after
 CPU hotplug
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When the last CPU of a legacy uncore die goes offline,
uncore_freq_remove_die_entry() clears control_cpu. During CPU hotplug
re-add, uncore_freq_add_entry() still populates sysfs attributes before
assigning the new control CPU. As a result, the current frequency read
returns -ENXIO and current_freq_khz is omitted from the recreated sysfs
group.

Assign control_cpu before the initial read paths and before
create_attr_group() so sysfs recreation uses the new online CPU. If
sysfs creation fails, restore control_cpu to -1 to keep the error path
state consistent.

Fixes: 4d73c6772ab7 ("platform/x86: intel-uncore-freq: Conditionally create attribute for read frequency")
Cc: stable@vger.kernel.org
Signed-off-by: Guixiong Wei <weiguixiong@bytedance.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20260602020752.3126-1-weiguixiong@bytedance.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

diff --git a/drivers/platform/x86/intel/uncore-frequency/uncore-frequency-common.c b/drivers/platform/x86/intel/uncore-frequency/uncore-frequency-common.c
index 3b554418a7a3..4bcafedf68ef 100644
--- a/drivers/platform/x86/intel/uncore-frequency/uncore-frequency-common.c
+++ b/drivers/platform/x86/intel/uncore-frequency/uncore-frequency-common.c
@@ -285,15 +285,20 @@ int uncore_freq_add_entry(struct uncore_data *data, int cpu)
 			  data->package_id, data->die_id);
 	}
 
+	/*
+	 * Set the control CPU before any read path so entry recreation after CPU
+	 * hotplug can populate read-only attributes from the new online CPU.
+	 */
+	data->control_cpu = cpu;
 	uncore_read(data, &data->initial_min_freq_khz, UNCORE_INDEX_MIN_FREQ);
 	uncore_read(data, &data->initial_max_freq_khz, UNCORE_INDEX_MAX_FREQ);
 
 	ret = create_attr_group(data, data->name);
 	if (ret) {
+		data->control_cpu = -1;
 		if (data->domain_id != UNCORE_DOMAIN_ID_INVALID)
 			ida_free(&intel_uncore_ida, data->seqnum_id);
 	} else {
-		data->control_cpu = cpu;
 		data->valid = true;
 	}