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Revision 2bbd00aef0671bfe3c2ca5ba67097246257de125 authored by Johannes Weiner on 26 February 2021, 01:16:47 UTC, committed by Linus Torvalds on 26 February 2021, 17:41:00 UTC 
mm: vmstat: fix NOHZ wakeups for node stat changes
 
On NOHZ, the periodic vmstat flushers on each CPU can go to sleep and
won't wake up until stat changes are detected in the per-cpu deltas of the
zone vmstat counters.

In commit 75ef71840539 ("mm, vmstat: add infrastructure for per-node
vmstats") per-node counters were introduced, and subsequently most stats
were moved from the zone to the node level.  However, the node counters
weren't added to the NOHZ wakeup detection.

In theory this can cause per-cpu errors to remain in the user-reported
stats indefinitely.  In practice this only affects a handful of sub
counters (file_mapped, dirty and writeback e.g.) because other page state
changes at the node level likely involve a change at the zone level as
well (alloc and free, lru ops).  Also, nobody has complained.

Fix it up for completeness: wake up vmstat refreshing on node changes.
Also remove the BUILD_BUG_ONs that assert counter size; we haven't relied
on it since we added sizeof() to the range calculation in commit
13c9aaf7fa01 ("mm/vmstat.c: fix NUMA statistics updates").

Link: https://lkml.kernel.org/r/20210202184342.118513-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent a052d4d
Raw File
gpio-tps65086.c 
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/
 *	Andrew F. Davis <afd@ti.com>
 *
 * Based on the TPS65912 driver
 */

#include <linux/gpio/driver.h>
#include <linux/module.h>
#include <linux/platform_device.h>

#include <linux/mfd/tps65086.h>

struct tps65086_gpio {
	struct gpio_chip chip;
	struct tps65086 *tps;
};

static int tps65086_gpio_get_direction(struct gpio_chip *chip,
				       unsigned offset)
{
	/* This device is output only */
	return GPIO_LINE_DIRECTION_OUT;
}

static int tps65086_gpio_direction_input(struct gpio_chip *chip,
					 unsigned offset)
{
	/* This device is output only */
	return -EINVAL;
}

static int tps65086_gpio_direction_output(struct gpio_chip *chip,
					  unsigned offset, int value)
{
	struct tps65086_gpio *gpio = gpiochip_get_data(chip);

	/* Set the initial value */
	regmap_update_bits(gpio->tps->regmap, TPS65086_GPOCTRL,
			   BIT(4 + offset), value ? BIT(4 + offset) : 0);

	return 0;
}

static int tps65086_gpio_get(struct gpio_chip *chip, unsigned offset)
{
	struct tps65086_gpio *gpio = gpiochip_get_data(chip);
	int ret, val;

	ret = regmap_read(gpio->tps->regmap, TPS65086_GPOCTRL, &val);
	if (ret < 0)
		return ret;

	return val & BIT(4 + offset);
}

static void tps65086_gpio_set(struct gpio_chip *chip, unsigned offset,
			      int value)
{
	struct tps65086_gpio *gpio = gpiochip_get_data(chip);

	regmap_update_bits(gpio->tps->regmap, TPS65086_GPOCTRL,
			   BIT(4 + offset), value ? BIT(4 + offset) : 0);
}

static const struct gpio_chip template_chip = {
	.label			= "tps65086-gpio",
	.owner			= THIS_MODULE,
	.get_direction		= tps65086_gpio_get_direction,
	.direction_input	= tps65086_gpio_direction_input,
	.direction_output	= tps65086_gpio_direction_output,
	.get			= tps65086_gpio_get,
	.set			= tps65086_gpio_set,
	.base			= -1,
	.ngpio			= 4,
	.can_sleep		= true,
};

static int tps65086_gpio_probe(struct platform_device *pdev)
{
	struct tps65086_gpio *gpio;
	int ret;

	gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
	if (!gpio)
		return -ENOMEM;

	platform_set_drvdata(pdev, gpio);

	gpio->tps = dev_get_drvdata(pdev->dev.parent);
	gpio->chip = template_chip;
	gpio->chip.parent = gpio->tps->dev;

	ret = gpiochip_add_data(&gpio->chip, gpio);
	if (ret < 0) {
		dev_err(&pdev->dev, "Could not register gpiochip, %d\n", ret);
		return ret;
	}

	return 0;
}

static int tps65086_gpio_remove(struct platform_device *pdev)
{
	struct tps65086_gpio *gpio = platform_get_drvdata(pdev);

	gpiochip_remove(&gpio->chip);

	return 0;
}

static const struct platform_device_id tps65086_gpio_id_table[] = {
	{ "tps65086-gpio", },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(platform, tps65086_gpio_id_table);

static struct platform_driver tps65086_gpio_driver = {
	.driver = {
		.name = "tps65086-gpio",
	},
	.probe = tps65086_gpio_probe,
	.remove = tps65086_gpio_remove,
	.id_table = tps65086_gpio_id_table,
};
module_platform_driver(tps65086_gpio_driver);

MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
MODULE_DESCRIPTION("TPS65086 GPIO driver");
MODULE_LICENSE("GPL v2");
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