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, 158 insertions, 0 deletions

diff --git a/include/sound/sof/control.h b/include/sound/sof/control.h
new file mode 100644
index 000000000..8d3300dd9
--- /dev/null
+++ b/include/sound/sof/control.h
@@ -0,0 +1,158 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
+/*
+ * This file is provided under a dual BSD/GPLv2 license.  When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * Copyright(c) 2018 Intel Corporation
+ */
+
+#ifndef __INCLUDE_SOUND_SOF_CONTROL_H__
+#define __INCLUDE_SOUND_SOF_CONTROL_H__
+
+#include <uapi/sound/sof/header.h>
+#include <sound/sof/header.h>
+
+/*
+ * Component Mixers and Controls
+ */
+
+/* channel positions - uses same values as ALSA */
+enum sof_ipc_chmap {
+	SOF_CHMAP_UNKNOWN = 0,
+	SOF_CHMAP_NA,		/**< N/A, silent */
+	SOF_CHMAP_MONO,		/**< mono stream */
+	SOF_CHMAP_FL,		/**< front left */
+	SOF_CHMAP_FR,		/**< front right */
+	SOF_CHMAP_RL,		/**< rear left */
+	SOF_CHMAP_RR,		/**< rear right */
+	SOF_CHMAP_FC,		/**< front centre */
+	SOF_CHMAP_LFE,		/**< LFE */
+	SOF_CHMAP_SL,		/**< side left */
+	SOF_CHMAP_SR,		/**< side right */
+	SOF_CHMAP_RC,		/**< rear centre */
+	SOF_CHMAP_FLC,		/**< front left centre */
+	SOF_CHMAP_FRC,		/**< front right centre */
+	SOF_CHMAP_RLC,		/**< rear left centre */
+	SOF_CHMAP_RRC,		/**< rear right centre */
+	SOF_CHMAP_FLW,		/**< front left wide */
+	SOF_CHMAP_FRW,		/**< front right wide */
+	SOF_CHMAP_FLH,		/**< front left high */
+	SOF_CHMAP_FCH,		/**< front centre high */
+	SOF_CHMAP_FRH,		/**< front right high */
+	SOF_CHMAP_TC,		/**< top centre */
+	SOF_CHMAP_TFL,		/**< top front left */
+	SOF_CHMAP_TFR,		/**< top front right */
+	SOF_CHMAP_TFC,		/**< top front centre */
+	SOF_CHMAP_TRL,		/**< top rear left */
+	SOF_CHMAP_TRR,		/**< top rear right */
+	SOF_CHMAP_TRC,		/**< top rear centre */
+	SOF_CHMAP_TFLC,		/**< top front left centre */
+	SOF_CHMAP_TFRC,		/**< top front right centre */
+	SOF_CHMAP_TSL,		/**< top side left */
+	SOF_CHMAP_TSR,		/**< top side right */
+	SOF_CHMAP_LLFE,		/**< left LFE */
+	SOF_CHMAP_RLFE,		/**< right LFE */
+	SOF_CHMAP_BC,		/**< bottom centre */
+	SOF_CHMAP_BLC,		/**< bottom left centre */
+	SOF_CHMAP_BRC,		/**< bottom right centre */
+	SOF_CHMAP_LAST = SOF_CHMAP_BRC,
+};
+
+/* control data type and direction */
+enum sof_ipc_ctrl_type {
+	/*  per channel data - uses struct sof_ipc_ctrl_value_chan */
+	SOF_CTRL_TYPE_VALUE_CHAN_GET = 0,
+	SOF_CTRL_TYPE_VALUE_CHAN_SET,
+	/* component data - uses struct sof_ipc_ctrl_value_comp */
+	SOF_CTRL_TYPE_VALUE_COMP_GET,
+	SOF_CTRL_TYPE_VALUE_COMP_SET,
+	/* bespoke data - uses struct sof_abi_hdr */
+	SOF_CTRL_TYPE_DATA_GET,
+	SOF_CTRL_TYPE_DATA_SET,
+};
+
+/* control command type */
+enum sof_ipc_ctrl_cmd {
+	SOF_CTRL_CMD_VOLUME = 0, /**< maps to ALSA volume style controls */
+	SOF_CTRL_CMD_ENUM,	/**< maps to ALSA enum style controls */
+	SOF_CTRL_CMD_SWITCH,	/**< maps to ALSA switch style controls */
+	SOF_CTRL_CMD_BINARY,	/**< maps to ALSA binary style controls */
+};
+
+/* generic channel mapped value data */
+struct sof_ipc_ctrl_value_chan {
+	uint32_t channel;	/**< channel map - enum sof_ipc_chmap */
+	uint32_t value;
+} __packed;
+
+/* generic component mapped value data */
+struct sof_ipc_ctrl_value_comp {
+	uint32_t index;	/**< component source/sink/control index in control */
+	union {
+		uint32_t uvalue;
+		int32_t svalue;
+	};
+} __packed;
+
+/* generic control data */
+struct sof_ipc_ctrl_data {
+	struct sof_ipc_reply rhdr;
+	uint32_t comp_id;
+
+	/* control access and data type */
+	uint32_t type;		/**< enum sof_ipc_ctrl_type */
+	uint32_t cmd;		/**< enum sof_ipc_ctrl_cmd */
+	uint32_t index;		/**< control index for comps > 1 control */
+
+	/* control data - can either be appended or DMAed from host */
+	struct sof_ipc_host_buffer buffer;
+	uint32_t num_elems;	/**< in array elems or bytes for data type */
+	uint32_t elems_remaining;	/**< elems remaining if sent in parts */
+
+	uint32_t msg_index;	/**< for large messages sent in parts */
+
+	/* reserved for future use */
+	uint32_t reserved[6];
+
+	/* control data - add new types if needed */
+	union {
+		/* channel values can be used by volume type controls */
+		DECLARE_FLEX_ARRAY(struct sof_ipc_ctrl_value_chan, chanv);
+		/* component values used by routing controls like mux, mixer */
+		DECLARE_FLEX_ARRAY(struct sof_ipc_ctrl_value_comp, compv);
+		/* data can be used by binary controls */
+		DECLARE_FLEX_ARRAY(struct sof_abi_hdr, data);
+	};
+} __packed;
+
+/** Event type */
+enum sof_ipc_ctrl_event_type {
+	SOF_CTRL_EVENT_GENERIC = 0,	/**< generic event */
+	SOF_CTRL_EVENT_GENERIC_METADATA,	/**< generic event with metadata */
+	SOF_CTRL_EVENT_KD,	/**< keyword detection event */
+	SOF_CTRL_EVENT_VAD,	/**< voice activity detection event */
+};
+
+/**
+ * Generic notification data.
+ */
+struct sof_ipc_comp_event {
+	struct sof_ipc_reply rhdr;
+	uint16_t src_comp_type;	/**< COMP_TYPE_ */
+	uint32_t src_comp_id;	/**< source component id */
+	uint32_t event_type;	/**< event type - SOF_CTRL_EVENT_* */
+	uint32_t num_elems;	/**< in array elems or bytes for data type */
+
+	/* reserved for future use */
+	uint32_t reserved[8];
+
+	/* control data - add new types if needed */
+	union {
+		/* data can be used by binary controls */
+		struct sof_abi_hdr data[0];
+		/* event specific values */
+		uint32_t event_value;
+	};
+} __packed;
+
+#endif