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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
hid-generic.c 
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  HID support for Linux
 *
 *  Copyright (c) 1999 Andreas Gal
 *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
 *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
 *  Copyright (c) 2007-2008 Oliver Neukum
 *  Copyright (c) 2006-2012 Jiri Kosina
 *  Copyright (c) 2012 Henrik Rydberg
 */

/*
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <asm/unaligned.h>
#include <asm/byteorder.h>

#include <linux/hid.h>

static struct hid_driver hid_generic;

static int __check_hid_generic(struct device_driver *drv, void *data)
{
	struct hid_driver *hdrv = to_hid_driver(drv);
	struct hid_device *hdev = data;

	if (hdrv == &hid_generic)
		return 0;

	return hid_match_device(hdev, hdrv) != NULL;
}

static bool hid_generic_match(struct hid_device *hdev,
			      bool ignore_special_driver)
{
	if (ignore_special_driver)
		return true;

	if (hdev->quirks & HID_QUIRK_HAVE_SPECIAL_DRIVER)
		return false;

	/*
	 * If any other driver wants the device, leave the device to this other
	 * driver.
	 */
	if (bus_for_each_drv(&hid_bus_type, NULL, hdev, __check_hid_generic))
		return false;

	return true;
}

static int hid_generic_probe(struct hid_device *hdev,
			     const struct hid_device_id *id)
{
	int ret;

	hdev->quirks |= HID_QUIRK_INPUT_PER_APP;

	ret = hid_parse(hdev);
	if (ret)
		return ret;

	return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
}

static const struct hid_device_id hid_table[] = {
	{ HID_DEVICE(HID_BUS_ANY, HID_GROUP_ANY, HID_ANY_ID, HID_ANY_ID) },
	{ }
};
MODULE_DEVICE_TABLE(hid, hid_table);

static struct hid_driver hid_generic = {
	.name = "hid-generic",
	.id_table = hid_table,
	.match = hid_generic_match,
	.probe = hid_generic_probe,
};
module_hid_driver(hid_generic);

MODULE_AUTHOR("Henrik Rydberg");
MODULE_DESCRIPTION("HID generic driver");
MODULE_LICENSE("GPL");
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