sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling buggrafted

alb_break_llc() decides whether to break LLC preference during active
load balance. It does so by testing that every runnable fair task on the
source rq prefers its LLC:

	env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable

But the two counters cover different sets. nr_pref_llc_running is updated
in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued,
so it follows queued tasks. h_nr_runnable is updated in set_delayed()/
clear_delayed() and drops delay-dequeued tasks.

So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted
in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks,
alb_break_llc() returns false, and active balance is free to pull a task
off its preferred LLC. Active balance only moves runnable tasks, and this
is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB
skips the per-task test in can_migrate_task(). The runnable set is the one
we want.

Fix it on the counter side. A task should be counted in
nr_pref_llc_running exactly while it is both queued on its preferred LLC
(pref_llc_queued) and runnable (!sched_delayed). Define that membership
once in task_pref_llc_runnable(), and adjust the counter only through
pref_llc_running_inc()/pref_llc_running_dec() from the four sites that
change either input: account_llc_enqueue(), account_llc_dequeue(),
set_delayed() and clear_delayed(). Gating every update on the same
predicate keeps the delay, wake and dequeue paths from double-counting
or underflowing; see the comments at those sites for the ordering.

nr_llc_running and sd->llc_counts are not touched and stay on queued
semantics.

Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC")
Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/
Reported-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Suggested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kayra Cizmeci <kayracizmeci@gmail.com>
Cc: <stable@kernel.org> # v7.2.x
Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com

1 files changed, 266 insertions, 0 deletions

diff --git a/drivers/input/misc/mc13783-pwrbutton.c b/drivers/input/misc/mc13783-pwrbutton.c
new file mode 100644
index 000000000..cb781ce96
--- /dev/null
+++ b/drivers/input/misc/mc13783-pwrbutton.c
@@ -0,0 +1,266 @@
+/*
+ * Copyright (C) 2011 Philippe Rétornaz
+ *
+ * Based on twl4030-pwrbutton driver by:
+ *     Peter De Schrijver <peter.de-schrijver@nokia.com>
+ *     Felipe Balbi <felipe.balbi@nokia.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335  USA
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/mc13783.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+struct mc13783_pwrb {
+	struct input_dev *pwr;
+	struct mc13xxx *mc13783;
+#define MC13783_PWRB_B1_POL_INVERT	(1 << 0)
+#define MC13783_PWRB_B2_POL_INVERT	(1 << 1)
+#define MC13783_PWRB_B3_POL_INVERT	(1 << 2)
+	int flags;
+	unsigned short keymap[3];
+};
+
+#define MC13783_REG_INTERRUPT_SENSE_1		5
+#define MC13783_IRQSENSE1_ONOFD1S		(1 << 3)
+#define MC13783_IRQSENSE1_ONOFD2S		(1 << 4)
+#define MC13783_IRQSENSE1_ONOFD3S		(1 << 5)
+
+#define MC13783_REG_POWER_CONTROL_2		15
+#define MC13783_POWER_CONTROL_2_ON1BDBNC	4
+#define MC13783_POWER_CONTROL_2_ON2BDBNC	6
+#define MC13783_POWER_CONTROL_2_ON3BDBNC	8
+#define MC13783_POWER_CONTROL_2_ON1BRSTEN	(1 << 1)
+#define MC13783_POWER_CONTROL_2_ON2BRSTEN	(1 << 2)
+#define MC13783_POWER_CONTROL_2_ON3BRSTEN	(1 << 3)
+
+static irqreturn_t button_irq(int irq, void *_priv)
+{
+	struct mc13783_pwrb *priv = _priv;
+	int val;
+
+	mc13xxx_reg_read(priv->mc13783, MC13783_REG_INTERRUPT_SENSE_1, &val);
+
+	switch (irq) {
+	case MC13783_IRQ_ONOFD1:
+		val = val & MC13783_IRQSENSE1_ONOFD1S ? 1 : 0;
+		if (priv->flags & MC13783_PWRB_B1_POL_INVERT)
+			val ^= 1;
+		input_report_key(priv->pwr, priv->keymap[0], val);
+		break;
+
+	case MC13783_IRQ_ONOFD2:
+		val = val & MC13783_IRQSENSE1_ONOFD2S ? 1 : 0;
+		if (priv->flags & MC13783_PWRB_B2_POL_INVERT)
+			val ^= 1;
+		input_report_key(priv->pwr, priv->keymap[1], val);
+		break;
+
+	case MC13783_IRQ_ONOFD3:
+		val = val & MC13783_IRQSENSE1_ONOFD3S ? 1 : 0;
+		if (priv->flags & MC13783_PWRB_B3_POL_INVERT)
+			val ^= 1;
+		input_report_key(priv->pwr, priv->keymap[2], val);
+		break;
+	}
+
+	input_sync(priv->pwr);
+
+	return IRQ_HANDLED;
+}
+
+static int mc13783_pwrbutton_probe(struct platform_device *pdev)
+{
+	const struct mc13xxx_buttons_platform_data *pdata;
+	struct mc13xxx *mc13783 = dev_get_drvdata(pdev->dev.parent);
+	struct input_dev *pwr;
+	struct mc13783_pwrb *priv;
+	int err = 0;
+	int reg = 0;
+
+	pdata = dev_get_platdata(&pdev->dev);
+	if (!pdata) {
+		dev_err(&pdev->dev, "missing platform data\n");
+		return -ENODEV;
+	}
+
+	pwr = input_allocate_device();
+	if (!pwr) {
+		dev_dbg(&pdev->dev, "Can't allocate power button\n");
+		return -ENOMEM;
+	}
+
+	priv = kzalloc_obj(*priv);
+	if (!priv) {
+		err = -ENOMEM;
+		dev_dbg(&pdev->dev, "Can't allocate power button\n");
+		goto free_input_dev;
+	}
+
+	reg |= (pdata->b1on_flags & 0x3) << MC13783_POWER_CONTROL_2_ON1BDBNC;
+	reg |= (pdata->b2on_flags & 0x3) << MC13783_POWER_CONTROL_2_ON2BDBNC;
+	reg |= (pdata->b3on_flags & 0x3) << MC13783_POWER_CONTROL_2_ON3BDBNC;
+
+	priv->pwr = pwr;
+	priv->mc13783 = mc13783;
+
+	mc13xxx_lock(mc13783);
+
+	if (pdata->b1on_flags & MC13783_BUTTON_ENABLE) {
+		priv->keymap[0] = pdata->b1on_key;
+		if (pdata->b1on_key != KEY_RESERVED)
+			__set_bit(pdata->b1on_key, pwr->keybit);
+
+		if (pdata->b1on_flags & MC13783_BUTTON_POL_INVERT)
+			priv->flags |= MC13783_PWRB_B1_POL_INVERT;
+
+		if (pdata->b1on_flags & MC13783_BUTTON_RESET_EN)
+			reg |= MC13783_POWER_CONTROL_2_ON1BRSTEN;
+
+		err = mc13xxx_irq_request(mc13783, MC13783_IRQ_ONOFD1,
+					  button_irq, "b1on", priv);
+		if (err) {
+			dev_dbg(&pdev->dev, "Can't request irq\n");
+			goto free_priv;
+		}
+	}
+
+	if (pdata->b2on_flags & MC13783_BUTTON_ENABLE) {
+		priv->keymap[1] = pdata->b2on_key;
+		if (pdata->b2on_key != KEY_RESERVED)
+			__set_bit(pdata->b2on_key, pwr->keybit);
+
+		if (pdata->b2on_flags & MC13783_BUTTON_POL_INVERT)
+			priv->flags |= MC13783_PWRB_B2_POL_INVERT;
+
+		if (pdata->b2on_flags & MC13783_BUTTON_RESET_EN)
+			reg |= MC13783_POWER_CONTROL_2_ON2BRSTEN;
+
+		err = mc13xxx_irq_request(mc13783, MC13783_IRQ_ONOFD2,
+					  button_irq, "b2on", priv);
+		if (err) {
+			dev_dbg(&pdev->dev, "Can't request irq\n");
+			goto free_irq_b1;
+		}
+	}
+
+	if (pdata->b3on_flags & MC13783_BUTTON_ENABLE) {
+		priv->keymap[2] = pdata->b3on_key;
+		if (pdata->b3on_key != KEY_RESERVED)
+			__set_bit(pdata->b3on_key, pwr->keybit);
+
+		if (pdata->b3on_flags & MC13783_BUTTON_POL_INVERT)
+			priv->flags |= MC13783_PWRB_B3_POL_INVERT;
+
+		if (pdata->b3on_flags & MC13783_BUTTON_RESET_EN)
+			reg |= MC13783_POWER_CONTROL_2_ON3BRSTEN;
+
+		err = mc13xxx_irq_request(mc13783, MC13783_IRQ_ONOFD3,
+					  button_irq, "b3on", priv);
+		if (err) {
+			dev_dbg(&pdev->dev, "Can't request irq: %d\n", err);
+			goto free_irq_b2;
+		}
+	}
+
+	mc13xxx_reg_rmw(mc13783, MC13783_REG_POWER_CONTROL_2, 0x3FE, reg);
+
+	mc13xxx_unlock(mc13783);
+
+	pwr->name = "mc13783_pwrbutton";
+	pwr->phys = "mc13783_pwrbutton/input0";
+	pwr->dev.parent = &pdev->dev;
+
+	pwr->keycode = priv->keymap;
+	pwr->keycodemax = ARRAY_SIZE(priv->keymap);
+	pwr->keycodesize = sizeof(priv->keymap[0]);
+	__set_bit(EV_KEY, pwr->evbit);
+
+	err = input_register_device(pwr);
+	if (err) {
+		dev_dbg(&pdev->dev, "Can't register power button: %d\n", err);
+		goto free_irq;
+	}
+
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+
+free_irq:
+	mc13xxx_lock(mc13783);
+
+	if (pdata->b3on_flags & MC13783_BUTTON_ENABLE)
+		mc13xxx_irq_free(mc13783, MC13783_IRQ_ONOFD3, priv);
+
+free_irq_b2:
+	if (pdata->b2on_flags & MC13783_BUTTON_ENABLE)
+		mc13xxx_irq_free(mc13783, MC13783_IRQ_ONOFD2, priv);
+
+free_irq_b1:
+	if (pdata->b1on_flags & MC13783_BUTTON_ENABLE)
+		mc13xxx_irq_free(mc13783, MC13783_IRQ_ONOFD1, priv);
+
+free_priv:
+	mc13xxx_unlock(mc13783);
+	kfree(priv);
+
+free_input_dev:
+	input_free_device(pwr);
+
+	return err;
+}
+
+static void mc13783_pwrbutton_remove(struct platform_device *pdev)
+{
+	struct mc13783_pwrb *priv = platform_get_drvdata(pdev);
+	const struct mc13xxx_buttons_platform_data *pdata;
+
+	pdata = dev_get_platdata(&pdev->dev);
+
+	mc13xxx_lock(priv->mc13783);
+
+	if (pdata->b3on_flags & MC13783_BUTTON_ENABLE)
+		mc13xxx_irq_free(priv->mc13783, MC13783_IRQ_ONOFD3, priv);
+	if (pdata->b2on_flags & MC13783_BUTTON_ENABLE)
+		mc13xxx_irq_free(priv->mc13783, MC13783_IRQ_ONOFD2, priv);
+	if (pdata->b1on_flags & MC13783_BUTTON_ENABLE)
+		mc13xxx_irq_free(priv->mc13783, MC13783_IRQ_ONOFD1, priv);
+
+	mc13xxx_unlock(priv->mc13783);
+
+	input_unregister_device(priv->pwr);
+	kfree(priv);
+}
+
+static struct platform_driver mc13783_pwrbutton_driver = {
+	.probe		= mc13783_pwrbutton_probe,
+	.remove		= mc13783_pwrbutton_remove,
+	.driver		= {
+		.name	= "mc13783-pwrbutton",
+	},
+};
+
+module_platform_driver(mc13783_pwrbutton_driver);
+
+MODULE_ALIAS("platform:mc13783-pwrbutton");
+MODULE_DESCRIPTION("MC13783 Power Button");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Philippe Retornaz");