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, 132 insertions, 0 deletions

diff --git a/sound/soc/sof/ipc4-priv.h b/sound/soc/sof/ipc4-priv.h
new file mode 100644
index 000000000..a8cdf9bc7
--- /dev/null
+++ b/sound/soc/sof/ipc4-priv.h
@@ -0,0 +1,132 @@
+/* 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) 2022 Intel Corporation
+ */
+
+#ifndef __SOUND_SOC_SOF_IPC4_PRIV_H
+#define __SOUND_SOC_SOF_IPC4_PRIV_H
+
+#include <linux/idr.h>
+#include <sound/sof/ext_manifest4.h>
+#include <sound/sof/ipc4/header.h>
+#include "sof-priv.h"
+
+/* The DSP window indices are fixed */
+#define SOF_IPC4_INBOX_WINDOW_IDX	0
+#define SOF_IPC4_OUTBOX_WINDOW_IDX	1
+#define SOF_IPC4_DEBUG_WINDOW_IDX	2
+
+enum sof_ipc4_mtrace_type {
+	SOF_IPC4_MTRACE_NOT_AVAILABLE = 0,
+	SOF_IPC4_MTRACE_INTEL_CAVS_1_5,
+	SOF_IPC4_MTRACE_INTEL_CAVS_1_8,
+	SOF_IPC4_MTRACE_INTEL_CAVS_2,
+};
+
+/**
+ * struct sof_ipc4_fw_module - IPC4 module info
+ * @sof_man4_module: Module info
+ * @fw_mod_cfg: Pointer to the module config start of the module
+ * @m_ida: Module instance identifier
+ * @private: Module private data
+ */
+struct sof_ipc4_fw_module {
+	struct sof_man4_module man4_module_entry;
+	const struct sof_man4_module_config *fw_mod_cfg;
+	struct ida m_ida;
+	void *private;
+};
+
+/**
+ * struct sof_ipc4_fw_library - IPC4 library information
+ * @sof_fw: SOF Firmware of the library
+ * @id: Library ID. 0 is reserved for basefw, external libraries must have unique
+ *	ID number between 1 and (sof_ipc4_fw_data.max_libs_count - 1)
+ *	Note: sof_ipc4_fw_data.max_libs_count == 1 implies that external libraries
+ *	are not supported
+ * @num_modules : Number of FW modules in the library
+ * @modules: Array of FW modules
+ */
+struct sof_ipc4_fw_library {
+	struct sof_firmware sof_fw;
+	const char *name;
+	u32 id;
+	int num_modules;
+	struct sof_ipc4_fw_module *modules;
+};
+
+/**
+ * struct sof_ipc4_fw_data - IPC4-specific data
+ * @manifest_fw_hdr_offset: FW header offset in the manifest
+ * @fw_lib_xa: XArray for firmware libraries, including basefw (ID = 0)
+ *	       Used to store the FW libraries and to manage the unique IDs of the
+ *	       libraries.
+ * @nhlt: NHLT table either from the BIOS or the topology manifest
+ * @mtrace_type: mtrace type supported on the booted platform
+ * @mtrace_log_bytes: log bytes as reported by the firmware via fw_config reply
+ * @num_playback_streams: max number of playback DMAs, needed for CHAIN_DMA offset
+ * @num_capture_streams: max number of capture DMAs
+ * @max_num_pipelines: max number of pipelines
+ * @max_libs_count: Maximum number of libraries support by the FW including the
+ *		    base firmware
+ * @fw_context_save: Firmware supports full context save and restore
+ * @libraries_restored: The libraries have been retained during firmware boot
+ *
+ * @load_library: Callback function for platform dependent library loading
+ * @pipeline_state_mutex: Mutex to protect pipeline triggers, ref counts, states and deletion
+ */
+struct sof_ipc4_fw_data {
+	u32 manifest_fw_hdr_offset;
+	struct xarray fw_lib_xa;
+	void *nhlt;
+	enum sof_ipc4_mtrace_type mtrace_type;
+	u32 mtrace_log_bytes;
+	int num_playback_streams;
+	int num_capture_streams;
+	int max_num_pipelines;
+	u32 max_libs_count;
+	bool fw_context_save;
+	bool libraries_restored;
+
+	int (*load_library)(struct snd_sof_dev *sdev,
+			    struct sof_ipc4_fw_library *fw_lib, bool reload);
+	void (*intel_configure_mic_privacy)(struct snd_sof_dev *sdev,
+					    struct sof_ipc4_intel_mic_privacy_cap *caps);
+	struct mutex pipeline_state_mutex; /* protect pipeline triggers, ref counts and states */
+};
+
+extern const struct sof_ipc_fw_loader_ops ipc4_loader_ops;
+extern const struct sof_ipc_tplg_ops ipc4_tplg_ops;
+extern const struct sof_ipc_tplg_control_ops tplg_ipc4_control_ops;
+extern const struct sof_ipc_pcm_ops ipc4_pcm_ops;
+extern const struct sof_ipc_fw_tracing_ops ipc4_mtrace_ops;
+
+int sof_ipc4_set_pipeline_state(struct snd_sof_dev *sdev, u32 instance_id, u32 state);
+int sof_ipc4_mtrace_update_pos(struct snd_sof_dev *sdev, int core);
+
+int sof_ipc4_complete_split_release(struct snd_sof_dev *sdev);
+int sof_ipc4_query_fw_configuration(struct snd_sof_dev *sdev);
+int sof_ipc4_reload_fw_libraries(struct snd_sof_dev *sdev);
+struct sof_ipc4_fw_module *sof_ipc4_find_module_by_uuid(struct snd_sof_dev *sdev,
+							const guid_t *uuid);
+
+struct snd_sof_widget *sof_ipc4_find_swidget_by_ids(struct snd_sof_dev *sdev,
+						    u32 module_id, int instance_id);
+
+struct sof_ipc4_base_module_cfg;
+void sof_ipc4_update_cpc_from_manifest(struct snd_sof_dev *sdev,
+				       struct sof_ipc4_fw_module *fw_module,
+				       struct sof_ipc4_base_module_cfg *basecfg);
+
+size_t sof_ipc4_find_debug_slot_offset_by_type(struct snd_sof_dev *sdev,
+					       u32 slot_type);
+
+void sof_ipc4_mic_privacy_state_change(struct snd_sof_dev *sdev, bool state);
+
+enum sof_ipc4_pipeline_state;
+const char *sof_ipc4_pipeline_state_str(enum sof_ipc4_pipeline_state state);
+
+#endif