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, 190 insertions, 0 deletions

diff --git a/sound/soc/sof/loader.c b/sound/soc/sof/loader.c
new file mode 100644
index 000000000..0baf316b0
--- /dev/null
+++ b/sound/soc/sof/loader.c
@@ -0,0 +1,190 @@
+// 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
+//
+// Author: Liam Girdwood <liam.r.girdwood@linux.intel.com>
+//
+// Generic firmware loader.
+//
+
+#include <linux/firmware.h>
+#include "sof-priv.h"
+#include "ops.h"
+
+int snd_sof_load_firmware_raw(struct snd_sof_dev *sdev)
+{
+	struct snd_sof_pdata *plat_data = sdev->pdata;
+	const char *fw_filename;
+	ssize_t ext_man_size;
+	int ret;
+
+	/* Don't request firmware again if firmware is already requested */
+	if (sdev->basefw.fw)
+		return 0;
+
+	fw_filename = kasprintf(GFP_KERNEL, "%s/%s",
+				plat_data->fw_filename_prefix,
+				plat_data->fw_filename);
+	if (!fw_filename)
+		return -ENOMEM;
+
+	ret = request_firmware(&sdev->basefw.fw, fw_filename, sdev->dev);
+
+	if (ret < 0) {
+		dev_err(sdev->dev,
+			"error: sof firmware file is missing, you might need to\n");
+		dev_err(sdev->dev,
+			"       download it from https://github.com/thesofproject/sof-bin/\n");
+		goto err;
+	} else {
+		dev_dbg(sdev->dev, "request_firmware %s successful\n",
+			fw_filename);
+	}
+
+	/* check for extended manifest */
+	ext_man_size = sdev->ipc->ops->fw_loader->parse_ext_manifest(sdev);
+	if (ext_man_size > 0) {
+		/* when no error occurred, drop extended manifest */
+		sdev->basefw.payload_offset = ext_man_size;
+	} else if (!ext_man_size) {
+		/* No extended manifest, so nothing to skip during FW load */
+		dev_dbg(sdev->dev, "firmware doesn't contain extended manifest\n");
+	} else {
+		ret = ext_man_size;
+		dev_err(sdev->dev, "error: firmware %s contains unsupported or invalid extended manifest: %d\n",
+			fw_filename, ret);
+	}
+
+err:
+	kfree(fw_filename);
+
+	return ret;
+}
+EXPORT_SYMBOL(snd_sof_load_firmware_raw);
+
+int snd_sof_load_firmware_memcpy(struct snd_sof_dev *sdev)
+{
+	int ret;
+
+	ret = snd_sof_load_firmware_raw(sdev);
+	if (ret < 0)
+		return ret;
+
+	/* make sure the FW header and file is valid */
+	ret = sdev->ipc->ops->fw_loader->validate(sdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "error: invalid FW header\n");
+		goto error;
+	}
+
+	/* prepare the DSP for FW loading */
+	ret = snd_sof_dsp_reset(sdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "error: failed to reset DSP\n");
+		goto error;
+	}
+
+	/* parse and load firmware modules to DSP */
+	if (sdev->ipc->ops->fw_loader->load_fw_to_dsp) {
+		ret = sdev->ipc->ops->fw_loader->load_fw_to_dsp(sdev);
+		if (ret < 0) {
+			dev_err(sdev->dev, "Firmware loading failed\n");
+			goto error;
+		}
+	}
+
+	return 0;
+
+error:
+	release_firmware(sdev->basefw.fw);
+	sdev->basefw.fw = NULL;
+	return ret;
+
+}
+EXPORT_SYMBOL(snd_sof_load_firmware_memcpy);
+
+int snd_sof_run_firmware(struct snd_sof_dev *sdev)
+{
+	int ret;
+
+	init_waitqueue_head(&sdev->boot_wait);
+
+	/* (re-)enable dsp dump */
+	sdev->dbg_dump_printed = false;
+	sdev->ipc_dump_printed = false;
+
+	/* create read-only fw_version debugfs to store boot version info */
+	if (sdev->first_boot) {
+		ret = snd_sof_debugfs_buf_item(sdev, &sdev->fw_version,
+					       sizeof(sdev->fw_version),
+					       "fw_version", 0444);
+		/* errors are only due to memory allocation, not debugfs */
+		if (ret < 0) {
+			dev_err(sdev->dev, "snd_sof_debugfs_buf_item failed\n");
+			return ret;
+		}
+	}
+
+	/* perform pre fw run operations */
+	ret = snd_sof_dsp_pre_fw_run(sdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "failed pre fw run op\n");
+		return ret;
+	}
+
+	dev_dbg(sdev->dev, "booting DSP firmware\n");
+
+	/* boot the firmware on the DSP */
+	ret = snd_sof_dsp_run(sdev);
+	if (ret < 0) {
+		snd_sof_dsp_dbg_dump(sdev, "Failed to start DSP",
+				     SOF_DBG_DUMP_MBOX | SOF_DBG_DUMP_PCI);
+		return ret;
+	}
+
+	/*
+	 * now wait for the DSP to boot. There are 3 possible outcomes:
+	 * 1. Boot wait times out indicating FW boot failure.
+	 * 2. FW boots successfully and fw_ready op succeeds.
+	 * 3. FW boots but fw_ready op fails.
+	 */
+	ret = wait_event_timeout(sdev->boot_wait,
+				 sdev->fw_state > SOF_FW_BOOT_IN_PROGRESS,
+				 msecs_to_jiffies(sdev->boot_timeout));
+	if (ret == 0) {
+		snd_sof_dsp_dbg_dump(sdev, "Firmware boot failure due to timeout",
+				     SOF_DBG_DUMP_REGS | SOF_DBG_DUMP_MBOX |
+				     SOF_DBG_DUMP_TEXT | SOF_DBG_DUMP_PCI);
+		return -EIO;
+	}
+
+	if (sdev->fw_state == SOF_FW_BOOT_READY_FAILED)
+		return -EIO; /* FW boots but fw_ready op failed */
+
+	dev_dbg(sdev->dev, "firmware boot complete\n");
+	sof_set_fw_state(sdev, SOF_FW_BOOT_COMPLETE);
+
+	/* perform post fw run operations */
+	ret = snd_sof_dsp_post_fw_run(sdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "error: failed post fw run op\n");
+		return ret;
+	}
+
+	if (sdev->ipc->ops->post_fw_boot)
+		return sdev->ipc->ops->post_fw_boot(sdev);
+
+	return 0;
+}
+EXPORT_SYMBOL(snd_sof_run_firmware);
+
+void snd_sof_fw_unload(struct snd_sof_dev *sdev)
+{
+	/* TODO: support module unloading at runtime */
+	release_firmware(sdev->basefw.fw);
+	sdev->basefw.fw = NULL;
+}
+EXPORT_SYMBOL(snd_sof_fw_unload);