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/sprd/common.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) create mode 100644 drivers/clk/sprd/common.c (limited to 'drivers/clk/sprd/common.c') diff --git a/drivers/clk/sprd/common.c b/drivers/clk/sprd/common.c new file mode 100644 index 000000000..0f2181617 --- /dev/null +++ b/drivers/clk/sprd/common.c @@ -0,0 +1,113 @@ +// SPDX-License-Identifier: GPL-2.0 +// +// Spreadtrum clock infrastructure +// +// Copyright (C) 2017 Spreadtrum, Inc. +// Author: Chunyan Zhang + +#include +#include +#include +#include +#include + +#include "common.h" + +static const struct regmap_config sprdclk_regmap_config = { + .reg_bits = 32, + .reg_stride = 4, + .val_bits = 32, + .fast_io = true, +}; + +static void sprd_clk_set_regmap(const struct sprd_clk_desc *desc, + struct regmap *regmap) +{ + int i; + struct sprd_clk_common *cclk; + + for (i = 0; i < desc->num_clk_clks; i++) { + cclk = desc->clk_clks[i]; + if (!cclk) + continue; + + cclk->regmap = regmap; + } +} + +int sprd_clk_regmap_init(struct platform_device *pdev, + const struct sprd_clk_desc *desc) +{ + void __iomem *base; + struct device *dev = &pdev->dev; + struct device_node *node = dev->of_node, *np; + struct regmap *regmap; + struct resource *res; + struct regmap_config reg_config = sprdclk_regmap_config; + + if (of_property_present(node, "sprd,syscon")) { + regmap = syscon_regmap_lookup_by_phandle(node, "sprd,syscon"); + if (IS_ERR(regmap)) { + pr_err("%s: failed to get syscon regmap\n", __func__); + return PTR_ERR(regmap); + } + } else if (of_device_is_compatible(np = of_get_parent(node), "syscon") || + (of_node_put(np), 0)) { + regmap = device_node_to_regmap(np); + of_node_put(np); + if (IS_ERR(regmap)) { + dev_err(dev, "failed to get regmap from its parent.\n"); + return PTR_ERR(regmap); + } + } else { + base = devm_platform_get_and_ioremap_resource(pdev, 0, &res); + if (IS_ERR(base)) + return PTR_ERR(base); + + reg_config.max_register = resource_size(res) - reg_config.reg_stride; + + regmap = devm_regmap_init_mmio(&pdev->dev, base, + ®_config); + if (IS_ERR(regmap)) { + pr_err("failed to init regmap\n"); + return PTR_ERR(regmap); + } + } + + sprd_clk_set_regmap(desc, regmap); + + return 0; +} +EXPORT_SYMBOL_GPL(sprd_clk_regmap_init); + +int sprd_clk_probe(struct device *dev, struct clk_hw_onecell_data *clkhw) +{ + int i, ret; + struct clk_hw *hw; + + for (i = 0; i < clkhw->num; i++) { + const char *name; + + hw = clkhw->hws[i]; + if (!hw) + continue; + + name = hw->init->name; + ret = devm_clk_hw_register(dev, hw); + if (ret) { + dev_err(dev, "Couldn't register clock %d - %s\n", + i, name); + return ret; + } + } + + ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get, clkhw); + if (ret) + dev_err(dev, "Failed to add clock provider\n"); + + return ret; +} +EXPORT_SYMBOL_GPL(sprd_clk_probe); + +MODULE_DESCRIPTION("Spreadtrum clock infrastructure"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1