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, 422 insertions, 0 deletions

diff --git a/drivers/phy/phy-common-props-test.c b/drivers/phy/phy-common-props-test.c
new file mode 100644
index 000000000..e937ec8a4
--- /dev/null
+++ b/drivers/phy/phy-common-props-test.c
@@ -0,0 +1,422 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * phy-common-props-test.c  --  Unit tests for PHY common properties API
+ *
+ * Copyright 2025-2026 NXP
+ */
+#include <kunit/test.h>
+#include <linux/property.h>
+#include <linux/phy/phy-common-props.h>
+#include <dt-bindings/phy/phy.h>
+
+/* Test: rx-polarity property is missing */
+static void phy_test_rx_polarity_is_missing(struct kunit *test)
+{
+	static const struct property_entry entries[] = {
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_rx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_NORMAL);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: rx-polarity has more values than rx-polarity-names */
+static void phy_test_rx_polarity_more_values_than_names(struct kunit *test)
+{
+	static const u32 rx_pol[] = { PHY_POL_NORMAL, PHY_POL_INVERT, PHY_POL_NORMAL };
+	static const char * const rx_pol_names[] = { "sgmii", "2500base-x" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("rx-polarity", rx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("rx-polarity-names", rx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_rx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: rx-polarity has 1 value and rx-polarity-names does not exist */
+static void phy_test_rx_polarity_single_value_no_names(struct kunit *test)
+{
+	static const u32 rx_pol[] = { PHY_POL_INVERT };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("rx-polarity", rx_pol),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_rx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_INVERT);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: rx-polarity-names has more values than rx-polarity */
+static void phy_test_rx_polarity_more_names_than_values(struct kunit *test)
+{
+	static const u32 rx_pol[] = { PHY_POL_NORMAL, PHY_POL_INVERT };
+	static const char * const rx_pol_names[] = { "sgmii", "2500base-x", "1000base-x" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("rx-polarity", rx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("rx-polarity-names", rx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_rx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: rx-polarity and rx-polarity-names have same length, find the name */
+static void phy_test_rx_polarity_find_by_name(struct kunit *test)
+{
+	static const u32 rx_pol[] = { PHY_POL_NORMAL, PHY_POL_INVERT, PHY_POL_AUTO };
+	static const char * const rx_pol_names[] = { "sgmii", "2500base-x", "usb-ss" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("rx-polarity", rx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("rx-polarity-names", rx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_rx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_NORMAL);
+
+	ret = phy_get_manual_rx_polarity(node, "2500base-x", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_INVERT);
+
+	ret = phy_get_rx_polarity(node, "usb-ss", BIT(PHY_POL_AUTO),
+				  PHY_POL_AUTO, &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_AUTO);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: same length, name not found, no "default" - error */
+static void phy_test_rx_polarity_name_not_found_no_default(struct kunit *test)
+{
+	static const u32 rx_pol[] = { PHY_POL_NORMAL, PHY_POL_INVERT };
+	static const char * const rx_pol_names[] = { "2500base-x", "1000base-x" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("rx-polarity", rx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("rx-polarity-names", rx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_rx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: same length, name not found, but "default" exists */
+static void phy_test_rx_polarity_name_not_found_with_default(struct kunit *test)
+{
+	static const u32 rx_pol[] = { PHY_POL_NORMAL, PHY_POL_INVERT };
+	static const char * const rx_pol_names[] = { "2500base-x", "default" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("rx-polarity", rx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("rx-polarity-names", rx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_rx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_INVERT);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: polarity found but value is unsupported */
+static void phy_test_rx_polarity_unsupported_value(struct kunit *test)
+{
+	static const u32 rx_pol[] = { PHY_POL_AUTO };
+	static const char * const rx_pol_names[] = { "sgmii" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("rx-polarity", rx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("rx-polarity-names", rx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_rx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, -EOPNOTSUPP);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: tx-polarity property is missing */
+static void phy_test_tx_polarity_is_missing(struct kunit *test)
+{
+	static const struct property_entry entries[] = {
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_tx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_NORMAL);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: tx-polarity has more values than tx-polarity-names */
+static void phy_test_tx_polarity_more_values_than_names(struct kunit *test)
+{
+	static const u32 tx_pol[] = { PHY_POL_NORMAL, PHY_POL_INVERT, PHY_POL_NORMAL };
+	static const char * const tx_pol_names[] = { "sgmii", "2500base-x" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("tx-polarity", tx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("tx-polarity-names", tx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_tx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: tx-polarity has 1 value and tx-polarity-names does not exist */
+static void phy_test_tx_polarity_single_value_no_names(struct kunit *test)
+{
+	static const u32 tx_pol[] = { PHY_POL_INVERT };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("tx-polarity", tx_pol),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_tx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_INVERT);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: tx-polarity-names has more values than tx-polarity */
+static void phy_test_tx_polarity_more_names_than_values(struct kunit *test)
+{
+	static const u32 tx_pol[] = { PHY_POL_NORMAL, PHY_POL_INVERT };
+	static const char * const tx_pol_names[] = { "sgmii", "2500base-x", "1000base-x" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("tx-polarity", tx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("tx-polarity-names", tx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_tx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: tx-polarity and tx-polarity-names have same length, find the name */
+static void phy_test_tx_polarity_find_by_name(struct kunit *test)
+{
+	static const u32 tx_pol[] = { PHY_POL_NORMAL, PHY_POL_INVERT, PHY_POL_NORMAL };
+	static const char * const tx_pol_names[] = { "sgmii", "2500base-x", "1000base-x" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("tx-polarity", tx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("tx-polarity-names", tx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_tx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_NORMAL);
+
+	ret = phy_get_manual_tx_polarity(node, "2500base-x", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_INVERT);
+
+	ret = phy_get_manual_tx_polarity(node, "1000base-x", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_NORMAL);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: same length, name not found, no "default" - error */
+static void phy_test_tx_polarity_name_not_found_no_default(struct kunit *test)
+{
+	static const u32 tx_pol[] = { PHY_POL_NORMAL, PHY_POL_INVERT };
+	static const char * const tx_pol_names[] = { "2500base-x", "1000base-x" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("tx-polarity", tx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("tx-polarity-names", tx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_tx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, -EINVAL);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: same length, name not found, but "default" exists */
+static void phy_test_tx_polarity_name_not_found_with_default(struct kunit *test)
+{
+	static const u32 tx_pol[] = { PHY_POL_NORMAL, PHY_POL_INVERT };
+	static const char * const tx_pol_names[] = { "2500base-x", "default" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("tx-polarity", tx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("tx-polarity-names", tx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_tx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val, PHY_POL_INVERT);
+
+	fwnode_remove_software_node(node);
+}
+
+/* Test: polarity found but value is unsupported (AUTO for TX) */
+static void phy_test_tx_polarity_unsupported_value(struct kunit *test)
+{
+	static const u32 tx_pol[] = { PHY_POL_AUTO };
+	static const char * const tx_pol_names[] = { "sgmii" };
+	static const struct property_entry entries[] = {
+		PROPERTY_ENTRY_U32_ARRAY("tx-polarity", tx_pol),
+		PROPERTY_ENTRY_STRING_ARRAY("tx-polarity-names", tx_pol_names),
+		{}
+	};
+	struct fwnode_handle *node;
+	unsigned int val;
+	int ret;
+
+	node = fwnode_create_software_node(entries, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+	ret = phy_get_manual_tx_polarity(node, "sgmii", &val);
+	KUNIT_EXPECT_EQ(test, ret, -EOPNOTSUPP);
+
+	fwnode_remove_software_node(node);
+}
+
+static struct kunit_case phy_common_props_test_cases[] = {
+	KUNIT_CASE(phy_test_rx_polarity_is_missing),
+	KUNIT_CASE(phy_test_rx_polarity_more_values_than_names),
+	KUNIT_CASE(phy_test_rx_polarity_single_value_no_names),
+	KUNIT_CASE(phy_test_rx_polarity_more_names_than_values),
+	KUNIT_CASE(phy_test_rx_polarity_find_by_name),
+	KUNIT_CASE(phy_test_rx_polarity_name_not_found_no_default),
+	KUNIT_CASE(phy_test_rx_polarity_name_not_found_with_default),
+	KUNIT_CASE(phy_test_rx_polarity_unsupported_value),
+	KUNIT_CASE(phy_test_tx_polarity_is_missing),
+	KUNIT_CASE(phy_test_tx_polarity_more_values_than_names),
+	KUNIT_CASE(phy_test_tx_polarity_single_value_no_names),
+	KUNIT_CASE(phy_test_tx_polarity_more_names_than_values),
+	KUNIT_CASE(phy_test_tx_polarity_find_by_name),
+	KUNIT_CASE(phy_test_tx_polarity_name_not_found_no_default),
+	KUNIT_CASE(phy_test_tx_polarity_name_not_found_with_default),
+	KUNIT_CASE(phy_test_tx_polarity_unsupported_value),
+	{}
+};
+
+static struct kunit_suite phy_common_props_test_suite = {
+	.name = "phy-common-props",
+	.test_cases = phy_common_props_test_cases,
+};
+
+kunit_test_suite(phy_common_props_test_suite);
+
+MODULE_DESCRIPTION("Test module for PHY common properties API");
+MODULE_AUTHOR("Vladimir Oltean <vladimir.oltean@nxp.com>");
+MODULE_LICENSE("GPL");