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, 163 insertions, 0 deletions

diff --git a/drivers/input/misc/twl4030-pwrbutton.c b/drivers/input/misc/twl4030-pwrbutton.c
new file mode 100644
index 000000000..3e94a5995
--- /dev/null
+++ b/drivers/input/misc/twl4030-pwrbutton.c
@@ -0,0 +1,163 @@
+/*
+ * TWL4030 Power Button Input Driver
+ *
+ * Copyright (C) 2008-2009 Nokia Corporation
+ *
+ * Written by Peter De Schrijver <peter.de-schrijver@nokia.com>
+ * Several fixes by 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/bits.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/property.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/twl.h>
+
+#define PWR_PWRON_IRQ BIT(0)
+
+struct twl_pwrbutton_chipdata {
+	u8 status_reg;
+	bool need_manual_irq;
+};
+
+static const struct twl_pwrbutton_chipdata twl4030_chipdata = {
+	.status_reg = 0xf,
+	.need_manual_irq = false,
+};
+
+static const struct twl_pwrbutton_chipdata twl6030_chipdata = {
+	.status_reg = 0x2,
+	.need_manual_irq = true,
+};
+
+static irqreturn_t powerbutton_irq(int irq, void *_pwr)
+{
+	struct input_dev *pwr = _pwr;
+	const struct twl_pwrbutton_chipdata *pdata = dev_get_drvdata(pwr->dev.parent);
+	int err;
+	u8 value;
+
+	err = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &value, pdata->status_reg);
+	if (!err)  {
+		pm_wakeup_event(pwr->dev.parent, 0);
+		input_report_key(pwr, KEY_POWER, value & PWR_PWRON_IRQ);
+		input_sync(pwr);
+	} else {
+		dev_err(pwr->dev.parent, "twl4030: i2c error %d while reading"
+			" TWL4030 PM_MASTER STS_HW_CONDITIONS register\n", err);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int twl4030_pwrbutton_probe(struct platform_device *pdev)
+{
+	const struct twl_pwrbutton_chipdata *pdata;
+	struct input_dev *pwr;
+	int irq = platform_get_irq(pdev, 0);
+	int err;
+
+	pdata = device_get_match_data(&pdev->dev);
+	if (!pdata)
+		return -EINVAL;
+
+	platform_set_drvdata(pdev, (void *)pdata);
+
+	pwr = devm_input_allocate_device(&pdev->dev);
+	if (!pwr) {
+		dev_err(&pdev->dev, "Can't allocate power button\n");
+		return -ENOMEM;
+	}
+
+	input_set_capability(pwr, EV_KEY, KEY_POWER);
+	pwr->name = "twl4030_pwrbutton";
+	pwr->phys = "twl4030_pwrbutton/input0";
+	pwr->dev.parent = &pdev->dev;
+
+	err = devm_request_threaded_irq(&pdev->dev, irq, NULL, powerbutton_irq,
+			IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING |
+			IRQF_ONESHOT,
+			"twl4030_pwrbutton", pwr);
+	if (err < 0) {
+		dev_err(&pdev->dev, "Can't get IRQ for pwrbutton: %d\n", err);
+		return err;
+	}
+
+	err = input_register_device(pwr);
+	if (err) {
+		dev_err(&pdev->dev, "Can't register power button: %d\n", err);
+		return err;
+	}
+
+	if (pdata->need_manual_irq) {
+		err = twl6030_interrupt_unmask(0x01, REG_INT_MSK_LINE_A);
+		if (err)
+			return err;
+
+		err = twl6030_interrupt_unmask(0x01, REG_INT_MSK_STS_A);
+		if (err)
+			return err;
+	}
+
+	device_init_wakeup(&pdev->dev, true);
+
+	return 0;
+}
+
+static void twl4030_pwrbutton_remove(struct platform_device *pdev)
+{
+	const struct twl_pwrbutton_chipdata *pdata = platform_get_drvdata(pdev);
+
+	if (pdata->need_manual_irq) {
+		twl6030_interrupt_mask(0x01, REG_INT_MSK_LINE_A);
+		twl6030_interrupt_mask(0x01, REG_INT_MSK_STS_A);
+	}
+}
+
+static const struct of_device_id twl4030_pwrbutton_dt_match_table[] = {
+	{
+		.compatible = "ti,twl4030-pwrbutton",
+		.data = &twl4030_chipdata,
+	},
+	{
+		.compatible = "ti,twl6030-pwrbutton",
+		.data = &twl6030_chipdata,
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, twl4030_pwrbutton_dt_match_table);
+
+static struct platform_driver twl4030_pwrbutton_driver = {
+	.probe		= twl4030_pwrbutton_probe,
+	.remove		= twl4030_pwrbutton_remove,
+	.driver		= {
+		.name	= "twl4030_pwrbutton",
+		.of_match_table = twl4030_pwrbutton_dt_match_table,
+	},
+};
+module_platform_driver(twl4030_pwrbutton_driver);
+
+MODULE_ALIAS("platform:twl4030_pwrbutton");
+MODULE_DESCRIPTION("Triton2 Power Button");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Peter De Schrijver <peter.de-schrijver@nokia.com>");
+MODULE_AUTHOR("Felipe Balbi <felipe.balbi@nokia.com>");
+