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, 302 insertions, 0 deletions

diff --git a/drivers/nvmem/rockchip-efuse.c b/drivers/nvmem/rockchip-efuse.c
new file mode 100644
index 000000000..013e67136
--- /dev/null
+++ b/drivers/nvmem/rockchip-efuse.c
@@ -0,0 +1,302 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Rockchip eFuse Driver
+ *
+ * Copyright (c) 2015 Rockchip Electronics Co. Ltd.
+ * Author: Caesar Wang <wxt@rock-chips.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-provider.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+
+#define RK3288_A_SHIFT		6
+#define RK3288_A_MASK		0x3ff
+#define RK3288_PGENB		BIT(3)
+#define RK3288_LOAD		BIT(2)
+#define RK3288_STROBE		BIT(1)
+#define RK3288_CSB		BIT(0)
+
+#define RK3328_SECURE_SIZES	96
+#define RK3328_INT_STATUS	0x0018
+#define RK3328_DOUT		0x0020
+#define RK3328_AUTO_CTRL	0x0024
+#define RK3328_INT_FINISH	BIT(0)
+#define RK3328_AUTO_ENB		BIT(0)
+#define RK3328_AUTO_RD		BIT(1)
+
+#define RK3399_A_SHIFT		16
+#define RK3399_A_MASK		0x3ff
+#define RK3399_NBYTES		4
+#define RK3399_STROBSFTSEL	BIT(9)
+#define RK3399_RSB		BIT(7)
+#define RK3399_PD		BIT(5)
+#define RK3399_PGENB		BIT(3)
+#define RK3399_LOAD		BIT(2)
+#define RK3399_STROBE		BIT(1)
+#define RK3399_CSB		BIT(0)
+
+#define REG_EFUSE_CTRL		0x0000
+#define REG_EFUSE_DOUT		0x0004
+
+struct rockchip_efuse_chip {
+	struct device *dev;
+	void __iomem *base;
+	struct clk *clk;
+};
+
+static int rockchip_rk3288_efuse_read(void *context, unsigned int offset,
+				      void *val, size_t bytes)
+{
+	struct rockchip_efuse_chip *efuse = context;
+	u8 *buf = val;
+	int ret;
+
+	ret = clk_prepare_enable(efuse->clk);
+	if (ret < 0) {
+		dev_err(efuse->dev, "failed to prepare/enable efuse clk\n");
+		return ret;
+	}
+
+	writel(RK3288_LOAD | RK3288_PGENB, efuse->base + REG_EFUSE_CTRL);
+	udelay(1);
+	while (bytes--) {
+		writel(readl(efuse->base + REG_EFUSE_CTRL) &
+			     (~(RK3288_A_MASK << RK3288_A_SHIFT)),
+			     efuse->base + REG_EFUSE_CTRL);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) |
+			     ((offset++ & RK3288_A_MASK) << RK3288_A_SHIFT),
+			     efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) |
+			     RK3288_STROBE, efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+		*buf++ = readb(efuse->base + REG_EFUSE_DOUT);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) &
+		       (~RK3288_STROBE), efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+	}
+
+	/* Switch to standby mode */
+	writel(RK3288_PGENB | RK3288_CSB, efuse->base + REG_EFUSE_CTRL);
+
+	clk_disable_unprepare(efuse->clk);
+
+	return 0;
+}
+
+static int rockchip_rk3328_efuse_read(void *context, unsigned int offset,
+				      void *val, size_t bytes)
+{
+	struct rockchip_efuse_chip *efuse = context;
+	unsigned int addr_start, addr_end, addr_offset, addr_len;
+	u32 out_value, status;
+	u8 *buf;
+	int ret, i = 0;
+
+	ret = clk_prepare_enable(efuse->clk);
+	if (ret < 0) {
+		dev_err(efuse->dev, "failed to prepare/enable efuse clk\n");
+		return ret;
+	}
+
+	/* 128 Byte efuse, 96 Byte for secure, 32 Byte for non-secure */
+	offset += RK3328_SECURE_SIZES;
+	addr_start = rounddown(offset, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_end = roundup(offset + bytes, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_offset = offset % RK3399_NBYTES;
+	addr_len = addr_end - addr_start;
+
+	buf = kzalloc(array3_size(addr_len, RK3399_NBYTES, sizeof(*buf)),
+		      GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto nomem;
+	}
+
+	while (addr_len--) {
+		writel(RK3328_AUTO_RD | RK3328_AUTO_ENB |
+		       ((addr_start++ & RK3399_A_MASK) << RK3399_A_SHIFT),
+		       efuse->base + RK3328_AUTO_CTRL);
+		udelay(4);
+		status = readl(efuse->base + RK3328_INT_STATUS);
+		if (!(status & RK3328_INT_FINISH)) {
+			ret = -EIO;
+			goto err;
+		}
+		out_value = readl(efuse->base + RK3328_DOUT);
+		writel(RK3328_INT_FINISH, efuse->base + RK3328_INT_STATUS);
+
+		memcpy(&buf[i], &out_value, RK3399_NBYTES);
+		i += RK3399_NBYTES;
+	}
+
+	memcpy(val, buf + addr_offset, bytes);
+err:
+	kfree(buf);
+nomem:
+	clk_disable_unprepare(efuse->clk);
+
+	return ret;
+}
+
+static int rockchip_rk3399_efuse_read(void *context, unsigned int offset,
+				      void *val, size_t bytes)
+{
+	struct rockchip_efuse_chip *efuse = context;
+	unsigned int addr_start, addr_end, addr_offset, addr_len;
+	u32 out_value;
+	u8 *buf;
+	int ret, i = 0;
+
+	ret = clk_prepare_enable(efuse->clk);
+	if (ret < 0) {
+		dev_err(efuse->dev, "failed to prepare/enable efuse clk\n");
+		return ret;
+	}
+
+	addr_start = rounddown(offset, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_end = roundup(offset + bytes, RK3399_NBYTES) / RK3399_NBYTES;
+	addr_offset = offset % RK3399_NBYTES;
+	addr_len = addr_end - addr_start;
+
+	buf = kzalloc(array3_size(addr_len, RK3399_NBYTES, sizeof(*buf)),
+		      GFP_KERNEL);
+	if (!buf) {
+		clk_disable_unprepare(efuse->clk);
+		return -ENOMEM;
+	}
+
+	writel(RK3399_LOAD | RK3399_PGENB | RK3399_STROBSFTSEL | RK3399_RSB,
+	       efuse->base + REG_EFUSE_CTRL);
+	udelay(1);
+	while (addr_len--) {
+		writel(readl(efuse->base + REG_EFUSE_CTRL) | RK3399_STROBE |
+		       ((addr_start++ & RK3399_A_MASK) << RK3399_A_SHIFT),
+		       efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+		out_value = readl(efuse->base + REG_EFUSE_DOUT);
+		writel(readl(efuse->base + REG_EFUSE_CTRL) & (~RK3399_STROBE),
+		       efuse->base + REG_EFUSE_CTRL);
+		udelay(1);
+
+		memcpy(&buf[i], &out_value, RK3399_NBYTES);
+		i += RK3399_NBYTES;
+	}
+
+	/* Switch to standby mode */
+	writel(RK3399_PD | RK3399_CSB, efuse->base + REG_EFUSE_CTRL);
+
+	memcpy(val, buf + addr_offset, bytes);
+
+	kfree(buf);
+
+	clk_disable_unprepare(efuse->clk);
+
+	return 0;
+}
+
+static struct nvmem_config econfig = {
+	.name = "rockchip-efuse",
+	.add_legacy_fixed_of_cells = true,
+	.type = NVMEM_TYPE_OTP,
+	.stride = 1,
+	.word_size = 1,
+	.read_only = true,
+};
+
+static const struct of_device_id rockchip_efuse_match[] = {
+	/* deprecated but kept around for dts binding compatibility */
+	{
+		.compatible = "rockchip,rockchip-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3066a-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3188-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3228-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3288-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3368-efuse",
+		.data = (void *)&rockchip_rk3288_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3328-efuse",
+		.data = (void *)&rockchip_rk3328_efuse_read,
+	},
+	{
+		.compatible = "rockchip,rk3399-efuse",
+		.data = (void *)&rockchip_rk3399_efuse_read,
+	},
+	{ /* sentinel */},
+};
+MODULE_DEVICE_TABLE(of, rockchip_efuse_match);
+
+static int rockchip_efuse_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct nvmem_device *nvmem;
+	struct rockchip_efuse_chip *efuse;
+	const void *data;
+	struct device *dev = &pdev->dev;
+
+	data = of_device_get_match_data(dev);
+	if (!data) {
+		dev_err(dev, "failed to get match data\n");
+		return -EINVAL;
+	}
+
+	efuse = devm_kzalloc(dev, sizeof(struct rockchip_efuse_chip),
+			     GFP_KERNEL);
+	if (!efuse)
+		return -ENOMEM;
+
+	efuse->base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(efuse->base))
+		return PTR_ERR(efuse->base);
+
+	efuse->clk = devm_clk_get(dev, "pclk_efuse");
+	if (IS_ERR(efuse->clk))
+		return PTR_ERR(efuse->clk);
+
+	efuse->dev = dev;
+	if (of_property_read_u32(dev->of_node, "rockchip,efuse-size",
+				 &econfig.size))
+		econfig.size = resource_size(res);
+	econfig.reg_read = data;
+	econfig.priv = efuse;
+	econfig.dev = efuse->dev;
+	nvmem = devm_nvmem_register(dev, &econfig);
+
+	return PTR_ERR_OR_ZERO(nvmem);
+}
+
+static struct platform_driver rockchip_efuse_driver = {
+	.probe = rockchip_efuse_probe,
+	.driver = {
+		.name = "rockchip-efuse",
+		.of_match_table = rockchip_efuse_match,
+	},
+};
+
+module_platform_driver(rockchip_efuse_driver);
+MODULE_DESCRIPTION("rockchip_efuse driver");
+MODULE_LICENSE("GPL v2");