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, 107 insertions, 0 deletions

diff --git a/include/sound/sof/trace.h b/include/sound/sof/trace.h
new file mode 100644
index 000000000..ac2ebb6fb
--- /dev/null
+++ b/include/sound/sof/trace.h
@@ -0,0 +1,107 @@
+/* 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_TRACE_H__
+#define __INCLUDE_SOUND_SOF_TRACE_H__
+
+#include <sound/sof/header.h>
+#include <sound/sof/stream.h>
+
+/*
+ * DMA for Trace
+ */
+
+#define SOF_TRACE_FILENAME_SIZE		32
+
+/* DMA for Trace params info - SOF_IPC_DEBUG_DMA_PARAMS */
+/* Deprecated - use sof_ipc_dma_trace_params_ext */
+struct sof_ipc_dma_trace_params {
+	struct sof_ipc_cmd_hdr hdr;
+	struct sof_ipc_host_buffer buffer;
+	uint32_t stream_tag;
+}  __packed;
+
+/* DMA for Trace params info - SOF_IPC_DEBUG_DMA_PARAMS_EXT */
+struct sof_ipc_dma_trace_params_ext {
+	struct sof_ipc_cmd_hdr hdr;
+	struct sof_ipc_host_buffer buffer;
+	uint32_t stream_tag;
+	uint64_t timestamp_ns; /* in nanosecond */
+	uint32_t reserved[8];
+}  __packed;
+
+/* DMA for Trace params info - SOF_IPC_DEBUG_DMA_PARAMS */
+struct sof_ipc_dma_trace_posn {
+	struct sof_ipc_reply rhdr;
+	uint32_t host_offset;	/* Offset of DMA host buffer */
+	uint32_t overflow;	/* overflow bytes if any */
+	uint32_t messages;	/* total trace messages */
+}  __packed;
+
+/* Values used in sof_ipc_trace_filter_elem: */
+
+/* bits 6..0 */
+#define SOF_IPC_TRACE_FILTER_ELEM_SET_LEVEL	0x01	/**< trace level for selected components */
+#define SOF_IPC_TRACE_FILTER_ELEM_BY_UUID	0x02	/**< filter by uuid key */
+#define SOF_IPC_TRACE_FILTER_ELEM_BY_PIPE	0x03	/**< filter by pipeline */
+#define SOF_IPC_TRACE_FILTER_ELEM_BY_COMP	0x04	/**< filter by component id */
+
+/* bit 7 */
+#define SOF_IPC_TRACE_FILTER_ELEM_FIN		0x80	/**< mark last filter in set */
+
+/* bits 31..8: Unused */
+
+/** part of sof_ipc_trace_filter, ABI3.17 */
+struct sof_ipc_trace_filter_elem {
+	uint32_t key;		/**< SOF_IPC_TRACE_FILTER_ELEM_ {LEVEL, UUID, COMP, PIPE} */
+	uint32_t value;		/**< element value */
+} __packed;
+
+/** Runtime tracing filtration data - SOF_IPC_TRACE_FILTER_UPDATE, ABI3.17 */
+struct sof_ipc_trace_filter {
+	struct sof_ipc_cmd_hdr hdr;	/**< IPC command header */
+	uint32_t elem_cnt;		/**< number of entries in elems[] array */
+	uint32_t reserved[8];		/**< reserved for future usage */
+	/** variable size array with new filtering settings */
+	struct sof_ipc_trace_filter_elem elems[];
+} __packed;
+
+/*
+ * Commom debug
+ */
+
+/*
+ * SOF panic codes
+ */
+#define SOF_IPC_PANIC_MAGIC			0x0dead000
+#define SOF_IPC_PANIC_MAGIC_MASK		0x0ffff000
+#define SOF_IPC_PANIC_CODE_MASK			0x00000fff
+#define SOF_IPC_PANIC_MEM			(SOF_IPC_PANIC_MAGIC | 0x0)
+#define SOF_IPC_PANIC_WORK			(SOF_IPC_PANIC_MAGIC | 0x1)
+#define SOF_IPC_PANIC_IPC			(SOF_IPC_PANIC_MAGIC | 0x2)
+#define SOF_IPC_PANIC_ARCH			(SOF_IPC_PANIC_MAGIC | 0x3)
+#define SOF_IPC_PANIC_PLATFORM			(SOF_IPC_PANIC_MAGIC | 0x4)
+#define SOF_IPC_PANIC_TASK			(SOF_IPC_PANIC_MAGIC | 0x5)
+#define SOF_IPC_PANIC_EXCEPTION			(SOF_IPC_PANIC_MAGIC | 0x6)
+#define SOF_IPC_PANIC_DEADLOCK			(SOF_IPC_PANIC_MAGIC | 0x7)
+#define SOF_IPC_PANIC_STACK			(SOF_IPC_PANIC_MAGIC | 0x8)
+#define SOF_IPC_PANIC_IDLE			(SOF_IPC_PANIC_MAGIC | 0x9)
+#define SOF_IPC_PANIC_WFI			(SOF_IPC_PANIC_MAGIC | 0xa)
+#define SOF_IPC_PANIC_ASSERT			(SOF_IPC_PANIC_MAGIC | 0xb)
+
+/* panic info include filename and line number
+ * filename array will not include null terminator if fully filled
+ */
+struct sof_ipc_panic_info {
+	struct sof_ipc_hdr hdr;
+	uint32_t code;			/* SOF_IPC_PANIC_ */
+	uint8_t filename[SOF_TRACE_FILENAME_SIZE];
+	uint32_t linenum;
+}  __packed;
+
+#endif