From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug 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 Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- drivers/reset/reset-qcom-pdc.c | 161 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 161 insertions(+) create mode 100644 drivers/reset/reset-qcom-pdc.c (limited to 'drivers/reset/reset-qcom-pdc.c') diff --git a/drivers/reset/reset-qcom-pdc.c b/drivers/reset/reset-qcom-pdc.c new file mode 100644 index 000000000..ae2b5aba7 --- /dev/null +++ b/drivers/reset/reset-qcom-pdc.c @@ -0,0 +1,161 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2018 The Linux Foundation. All rights reserved. + */ + +#include +#include +#include +#include +#include + +#include + +#define RPMH_SDM845_PDC_SYNC_RESET 0x100 +#define RPMH_SC7280_PDC_SYNC_RESET 0x1000 + +struct qcom_pdc_reset_map { + u8 bit; +}; + +struct qcom_pdc_reset_desc { + const struct qcom_pdc_reset_map *resets; + size_t num_resets; + unsigned int offset; +}; + +struct qcom_pdc_reset_data { + struct reset_controller_dev rcdev; + struct regmap *regmap; + const struct qcom_pdc_reset_desc *desc; +}; + +static const struct regmap_config pdc_regmap_config = { + .name = "pdc-reset", + .reg_bits = 32, + .reg_stride = 4, + .val_bits = 32, + .max_register = 0x20000, +}; + +static const struct qcom_pdc_reset_map sdm845_pdc_resets[] = { + [PDC_APPS_SYNC_RESET] = {0}, + [PDC_SP_SYNC_RESET] = {1}, + [PDC_AUDIO_SYNC_RESET] = {2}, + [PDC_SENSORS_SYNC_RESET] = {3}, + [PDC_AOP_SYNC_RESET] = {4}, + [PDC_DEBUG_SYNC_RESET] = {5}, + [PDC_GPU_SYNC_RESET] = {6}, + [PDC_DISPLAY_SYNC_RESET] = {7}, + [PDC_COMPUTE_SYNC_RESET] = {8}, + [PDC_MODEM_SYNC_RESET] = {9}, +}; + +static const struct qcom_pdc_reset_desc sdm845_pdc_reset_desc = { + .resets = sdm845_pdc_resets, + .num_resets = ARRAY_SIZE(sdm845_pdc_resets), + .offset = RPMH_SDM845_PDC_SYNC_RESET, +}; + +static const struct qcom_pdc_reset_map sc7280_pdc_resets[] = { + [PDC_APPS_SYNC_RESET] = {0}, + [PDC_SP_SYNC_RESET] = {1}, + [PDC_AUDIO_SYNC_RESET] = {2}, + [PDC_SENSORS_SYNC_RESET] = {3}, + [PDC_AOP_SYNC_RESET] = {4}, + [PDC_DEBUG_SYNC_RESET] = {5}, + [PDC_GPU_SYNC_RESET] = {6}, + [PDC_DISPLAY_SYNC_RESET] = {7}, + [PDC_COMPUTE_SYNC_RESET] = {8}, + [PDC_MODEM_SYNC_RESET] = {9}, + [PDC_WLAN_RF_SYNC_RESET] = {10}, + [PDC_WPSS_SYNC_RESET] = {11}, +}; + +static const struct qcom_pdc_reset_desc sc7280_pdc_reset_desc = { + .resets = sc7280_pdc_resets, + .num_resets = ARRAY_SIZE(sc7280_pdc_resets), + .offset = RPMH_SC7280_PDC_SYNC_RESET, +}; + +static inline struct qcom_pdc_reset_data *to_qcom_pdc_reset_data( + struct reset_controller_dev *rcdev) +{ + return container_of(rcdev, struct qcom_pdc_reset_data, rcdev); +} + +static int qcom_pdc_control_assert(struct reset_controller_dev *rcdev, + unsigned long idx) +{ + struct qcom_pdc_reset_data *data = to_qcom_pdc_reset_data(rcdev); + u32 mask = BIT(data->desc->resets[idx].bit); + + return regmap_update_bits(data->regmap, data->desc->offset, mask, mask); +} + +static int qcom_pdc_control_deassert(struct reset_controller_dev *rcdev, + unsigned long idx) +{ + struct qcom_pdc_reset_data *data = to_qcom_pdc_reset_data(rcdev); + u32 mask = BIT(data->desc->resets[idx].bit); + + return regmap_update_bits(data->regmap, data->desc->offset, mask, 0); +} + +static const struct reset_control_ops qcom_pdc_reset_ops = { + .assert = qcom_pdc_control_assert, + .deassert = qcom_pdc_control_deassert, +}; + +static int qcom_pdc_reset_probe(struct platform_device *pdev) +{ + const struct qcom_pdc_reset_desc *desc; + struct qcom_pdc_reset_data *data; + struct device *dev = &pdev->dev; + void __iomem *base; + + desc = device_get_match_data(&pdev->dev); + if (!desc) + return -EINVAL; + + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + data->desc = desc; + base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(base)) + return PTR_ERR(base); + + data->regmap = devm_regmap_init_mmio(dev, base, &pdc_regmap_config); + if (IS_ERR(data->regmap)) { + dev_err(dev, "Unable to initialize regmap\n"); + return PTR_ERR(data->regmap); + } + + data->rcdev.owner = THIS_MODULE; + data->rcdev.ops = &qcom_pdc_reset_ops; + data->rcdev.nr_resets = desc->num_resets; + data->rcdev.of_node = dev->of_node; + + return devm_reset_controller_register(dev, &data->rcdev); +} + +static const struct of_device_id qcom_pdc_reset_of_match[] = { + { .compatible = "qcom,sc7280-pdc-global", .data = &sc7280_pdc_reset_desc }, + { .compatible = "qcom,sdm845-pdc-global", .data = &sdm845_pdc_reset_desc }, + {} +}; +MODULE_DEVICE_TABLE(of, qcom_pdc_reset_of_match); + +static struct platform_driver qcom_pdc_reset_driver = { + .probe = qcom_pdc_reset_probe, + .driver = { + .name = "qcom_pdc_reset", + .of_match_table = qcom_pdc_reset_of_match, + }, +}; +module_platform_driver(qcom_pdc_reset_driver); + +MODULE_DESCRIPTION("Qualcomm PDC Reset Driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1