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/clk/mediatek/reset.c | 174 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 174 insertions(+) create mode 100644 drivers/clk/mediatek/reset.c (limited to 'drivers/clk/mediatek/reset.c') diff --git a/drivers/clk/mediatek/reset.c b/drivers/clk/mediatek/reset.c new file mode 100644 index 000000000..2e3303975 --- /dev/null +++ b/drivers/clk/mediatek/reset.c @@ -0,0 +1,174 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2014 MediaTek Inc. + */ + +#include +#include +#include +#include +#include +#include + +#include "reset.h" + +static inline struct mtk_clk_rst_data *to_mtk_clk_rst_data(struct reset_controller_dev *rcdev) +{ + return container_of(rcdev, struct mtk_clk_rst_data, rcdev); +} + +static int mtk_reset_update(struct reset_controller_dev *rcdev, + unsigned long id, bool deassert) +{ + struct mtk_clk_rst_data *data = to_mtk_clk_rst_data(rcdev); + unsigned int val = deassert ? 0 : ~0; + + return regmap_update_bits(data->regmap, + data->desc->rst_bank_ofs[id / RST_NR_PER_BANK], + BIT(id % RST_NR_PER_BANK), val); +} + +static int mtk_reset_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return mtk_reset_update(rcdev, id, false); +} + +static int mtk_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return mtk_reset_update(rcdev, id, true); +} + +static int mtk_reset(struct reset_controller_dev *rcdev, unsigned long id) +{ + int ret; + + ret = mtk_reset_assert(rcdev, id); + if (ret) + return ret; + + return mtk_reset_deassert(rcdev, id); +} + +static int mtk_reset_update_set_clr(struct reset_controller_dev *rcdev, + unsigned long id, bool deassert) +{ + struct mtk_clk_rst_data *data = to_mtk_clk_rst_data(rcdev); + unsigned int deassert_ofs = deassert ? 0x4 : 0; + + return regmap_write(data->regmap, + data->desc->rst_bank_ofs[id / RST_NR_PER_BANK] + + deassert_ofs, + BIT(id % RST_NR_PER_BANK)); +} + +static int mtk_reset_assert_set_clr(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return mtk_reset_update_set_clr(rcdev, id, false); +} + +static int mtk_reset_deassert_set_clr(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return mtk_reset_update_set_clr(rcdev, id, true); +} + +static int mtk_reset_set_clr(struct reset_controller_dev *rcdev, + unsigned long id) +{ + int ret; + + ret = mtk_reset_assert_set_clr(rcdev, id); + if (ret) + return ret; + return mtk_reset_deassert_set_clr(rcdev, id); +} + +static const struct reset_control_ops mtk_reset_ops = { + .assert = mtk_reset_assert, + .deassert = mtk_reset_deassert, + .reset = mtk_reset, +}; + +static const struct reset_control_ops mtk_reset_ops_set_clr = { + .assert = mtk_reset_assert_set_clr, + .deassert = mtk_reset_deassert_set_clr, + .reset = mtk_reset_set_clr, +}; + +static int reset_xlate(struct reset_controller_dev *rcdev, + const struct of_phandle_args *reset_spec) +{ + struct mtk_clk_rst_data *data = to_mtk_clk_rst_data(rcdev); + + if (reset_spec->args[0] >= rcdev->nr_resets || + reset_spec->args[0] >= data->desc->rst_idx_map_nr) + return -EINVAL; + + return data->desc->rst_idx_map[reset_spec->args[0]]; +} + +int mtk_register_reset_controller_with_dev(struct device *dev, + const struct mtk_clk_rst_desc *desc) +{ + struct device_node *np = dev->of_node; + struct regmap *regmap; + const struct reset_control_ops *rcops = NULL; + struct mtk_clk_rst_data *data; + int ret; + + if (!desc) { + dev_err(dev, "mtk clock reset desc is NULL\n"); + return -EINVAL; + } + + switch (desc->version) { + case MTK_RST_SIMPLE: + rcops = &mtk_reset_ops; + break; + case MTK_RST_SET_CLR: + rcops = &mtk_reset_ops_set_clr; + break; + default: + dev_err(dev, "Unknown reset version %d\n", desc->version); + return -EINVAL; + } + + regmap = device_node_to_regmap(np); + if (IS_ERR(regmap)) { + dev_err(dev, "Cannot find regmap %pe\n", regmap); + return PTR_ERR(regmap); + } + + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + data->desc = desc; + data->regmap = regmap; + data->rcdev.owner = THIS_MODULE; + data->rcdev.ops = rcops; + data->rcdev.of_node = np; + data->rcdev.dev = dev; + + if (data->desc->rst_idx_map_nr > 0) { + data->rcdev.of_reset_n_cells = 1; + data->rcdev.nr_resets = desc->rst_idx_map_nr; + data->rcdev.of_xlate = reset_xlate; + } else { + data->rcdev.nr_resets = desc->rst_bank_nr * RST_NR_PER_BANK; + } + + ret = devm_reset_controller_register(dev, &data->rcdev); + if (ret) { + dev_err(dev, "could not register reset controller: %d\n", ret); + return ret; + } + + return 0; +} +EXPORT_SYMBOL_GPL(mtk_register_reset_controller_with_dev); + +MODULE_LICENSE("GPL"); -- cgit v1.3.1