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, 310 insertions, 0 deletions

diff --git a/drivers/input/misc/drv2665.c b/drivers/input/misc/drv2665.c
new file mode 100644
index 000000000..4f8c1f69a
--- /dev/null
+++ b/drivers/input/misc/drv2665.c
@@ -0,0 +1,310 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * DRV2665 haptics driver family
+ *
+ * Author: Dan Murphy <dmurphy@ti.com>
+ *
+ * Copyright: (C) 2015 Texas Instruments, Inc.
+ */
+
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/regulator/consumer.h>
+
+/* Control registers */
+#define DRV2665_STATUS	0x00
+#define DRV2665_CTRL_1	0x01
+#define DRV2665_CTRL_2	0x02
+#define DRV2665_FIFO	0x0b
+
+/* Status Register */
+#define DRV2665_FIFO_FULL		BIT(0)
+#define DRV2665_FIFO_EMPTY		BIT(1)
+
+/* Control 1 Register */
+#define DRV2665_25_VPP_GAIN		0x00
+#define DRV2665_50_VPP_GAIN		0x01
+#define DRV2665_75_VPP_GAIN		0x02
+#define DRV2665_100_VPP_GAIN		0x03
+#define DRV2665_DIGITAL_IN		0xfc
+#define DRV2665_ANALOG_IN		BIT(2)
+
+/* Control 2 Register */
+#define DRV2665_BOOST_EN		BIT(1)
+#define DRV2665_STANDBY			BIT(6)
+#define DRV2665_DEV_RST			BIT(7)
+#define DRV2665_5_MS_IDLE_TOUT		0x00
+#define DRV2665_10_MS_IDLE_TOUT		0x04
+#define DRV2665_15_MS_IDLE_TOUT		0x08
+#define DRV2665_20_MS_IDLE_TOUT		0x0c
+
+/**
+ * struct drv2665_data -
+ * @input_dev: Pointer to the input device
+ * @client: Pointer to the I2C client
+ * @regmap: Register map of the device
+ * @work: Work item used to off load the enable/disable of the vibration
+ * @regulator: Pointer to the regulator for the IC
+ */
+struct drv2665_data {
+	struct input_dev *input_dev;
+	struct i2c_client *client;
+	struct regmap *regmap;
+	struct work_struct work;
+	struct regulator *regulator;
+};
+
+/* 8kHz Sine wave to stream to the FIFO */
+static const u8 drv2665_sine_wave_form[] = {
+	0x00, 0x10, 0x20, 0x2e, 0x3c, 0x48, 0x53, 0x5b, 0x61, 0x65, 0x66,
+	0x65, 0x61, 0x5b, 0x53, 0x48, 0x3c, 0x2e, 0x20, 0x10,
+	0x00, 0xf0, 0xe0, 0xd2, 0xc4, 0xb8, 0xad, 0xa5, 0x9f, 0x9b, 0x9a,
+	0x9b, 0x9f, 0xa5, 0xad, 0xb8, 0xc4, 0xd2, 0xe0, 0xf0, 0x00,
+};
+
+static const struct reg_default drv2665_reg_defs[] = {
+	{ DRV2665_STATUS, 0x02 },
+	{ DRV2665_CTRL_1, 0x28 },
+	{ DRV2665_CTRL_2, 0x40 },
+	{ DRV2665_FIFO, 0x00 },
+};
+
+static void drv2665_worker(struct work_struct *work)
+{
+	struct drv2665_data *haptics =
+				container_of(work, struct drv2665_data, work);
+	unsigned int read_buf;
+	int error;
+
+	error = regmap_read(haptics->regmap, DRV2665_STATUS, &read_buf);
+	if (error) {
+		dev_err(&haptics->client->dev,
+			"Failed to read status: %d\n", error);
+		return;
+	}
+
+	if (read_buf & DRV2665_FIFO_EMPTY) {
+		error = regmap_bulk_write(haptics->regmap,
+					  DRV2665_FIFO,
+					  drv2665_sine_wave_form,
+					  ARRAY_SIZE(drv2665_sine_wave_form));
+		if (error) {
+			dev_err(&haptics->client->dev,
+				"Failed to write FIFO: %d\n", error);
+			return;
+		}
+	}
+}
+
+static int drv2665_haptics_play(struct input_dev *input, void *data,
+				struct ff_effect *effect)
+{
+	struct drv2665_data *haptics = input_get_drvdata(input);
+
+	schedule_work(&haptics->work);
+
+	return 0;
+}
+
+static void drv2665_close(struct input_dev *input)
+{
+	struct drv2665_data *haptics = input_get_drvdata(input);
+	int error;
+
+	cancel_work_sync(&haptics->work);
+
+	error = regmap_update_bits(haptics->regmap, DRV2665_CTRL_2,
+				   DRV2665_STANDBY, DRV2665_STANDBY);
+	if (error)
+		dev_err(&haptics->client->dev,
+			"Failed to enter standby mode: %d\n", error);
+}
+
+static const struct reg_sequence drv2665_init_regs[] = {
+	{ DRV2665_CTRL_2, 0 | DRV2665_10_MS_IDLE_TOUT },
+	{ DRV2665_CTRL_1, DRV2665_25_VPP_GAIN },
+};
+
+static int drv2665_init(struct drv2665_data *haptics)
+{
+	int error;
+
+	error = regmap_register_patch(haptics->regmap,
+				      drv2665_init_regs,
+				      ARRAY_SIZE(drv2665_init_regs));
+	if (error) {
+		dev_err(&haptics->client->dev,
+			"Failed to write init registers: %d\n",
+			error);
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct regmap_config drv2665_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = DRV2665_FIFO,
+	.reg_defaults = drv2665_reg_defs,
+	.num_reg_defaults = ARRAY_SIZE(drv2665_reg_defs),
+	.cache_type = REGCACHE_NONE,
+};
+
+static int drv2665_probe(struct i2c_client *client)
+{
+	struct drv2665_data *haptics;
+	int error;
+
+	haptics = devm_kzalloc(&client->dev, sizeof(*haptics), GFP_KERNEL);
+	if (!haptics)
+		return -ENOMEM;
+
+	haptics->regulator = devm_regulator_get(&client->dev, "vbat");
+	if (IS_ERR(haptics->regulator)) {
+		error = PTR_ERR(haptics->regulator);
+		dev_err(&client->dev,
+			"unable to get regulator, error: %d\n", error);
+		return error;
+	}
+
+	haptics->input_dev = devm_input_allocate_device(&client->dev);
+	if (!haptics->input_dev) {
+		dev_err(&client->dev, "Failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	haptics->input_dev->name = "drv2665:haptics";
+	haptics->input_dev->dev.parent = client->dev.parent;
+	haptics->input_dev->close = drv2665_close;
+	input_set_drvdata(haptics->input_dev, haptics);
+	input_set_capability(haptics->input_dev, EV_FF, FF_RUMBLE);
+
+	error = input_ff_create_memless(haptics->input_dev, NULL,
+					drv2665_haptics_play);
+	if (error) {
+		dev_err(&client->dev, "input_ff_create() failed: %d\n",
+			error);
+		return error;
+	}
+
+	INIT_WORK(&haptics->work, drv2665_worker);
+
+	haptics->client = client;
+	i2c_set_clientdata(client, haptics);
+
+	haptics->regmap = devm_regmap_init_i2c(client, &drv2665_regmap_config);
+	if (IS_ERR(haptics->regmap)) {
+		error = PTR_ERR(haptics->regmap);
+		dev_err(&client->dev, "Failed to allocate register map: %d\n",
+			error);
+		return error;
+	}
+
+	error = drv2665_init(haptics);
+	if (error) {
+		dev_err(&client->dev, "Device init failed: %d\n", error);
+		return error;
+	}
+
+	error = input_register_device(haptics->input_dev);
+	if (error) {
+		dev_err(&client->dev, "couldn't register input device: %d\n",
+			error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int drv2665_suspend(struct device *dev)
+{
+	struct drv2665_data *haptics = dev_get_drvdata(dev);
+	int error;
+
+	guard(mutex)(&haptics->input_dev->mutex);
+
+	if (input_device_enabled(haptics->input_dev)) {
+		error = regmap_update_bits(haptics->regmap, DRV2665_CTRL_2,
+					   DRV2665_STANDBY, DRV2665_STANDBY);
+		if (error) {
+			dev_err(dev, "Failed to set standby mode\n");
+			regulator_disable(haptics->regulator);
+			return error;
+		}
+
+		error = regulator_disable(haptics->regulator);
+		if (error) {
+			dev_err(dev, "Failed to disable regulator\n");
+			regmap_update_bits(haptics->regmap,
+					   DRV2665_CTRL_2,
+					   DRV2665_STANDBY, 0);
+			return error;
+		}
+	}
+
+	return 0;
+}
+
+static int drv2665_resume(struct device *dev)
+{
+	struct drv2665_data *haptics = dev_get_drvdata(dev);
+	int error;
+
+	guard(mutex)(&haptics->input_dev->mutex);
+
+	if (input_device_enabled(haptics->input_dev)) {
+		error = regulator_enable(haptics->regulator);
+		if (error) {
+			dev_err(dev, "Failed to enable regulator\n");
+			return error;
+		}
+
+		error = regmap_update_bits(haptics->regmap, DRV2665_CTRL_2,
+					   DRV2665_STANDBY, 0);
+		if (error) {
+			dev_err(dev, "Failed to unset standby mode\n");
+			regulator_disable(haptics->regulator);
+			return error;
+		}
+
+	}
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(drv2665_pm_ops, drv2665_suspend, drv2665_resume);
+
+static const struct i2c_device_id drv2665_id[] = {
+	{ .name = "drv2665" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, drv2665_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id drv2665_of_match[] = {
+	{ .compatible = "ti,drv2665", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, drv2665_of_match);
+#endif
+
+static struct i2c_driver drv2665_driver = {
+	.probe		= drv2665_probe,
+	.driver		= {
+		.name	= "drv2665-haptics",
+		.of_match_table = of_match_ptr(drv2665_of_match),
+		.pm	= pm_sleep_ptr(&drv2665_pm_ops),
+	},
+	.id_table = drv2665_id,
+};
+module_i2c_driver(drv2665_driver);
+
+MODULE_DESCRIPTION("TI DRV2665 haptics driver");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Dan Murphy <dmurphy@ti.com>");