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/nvmem/meson-efuse.c | 107 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 107 insertions(+) create mode 100644 drivers/nvmem/meson-efuse.c (limited to 'drivers/nvmem/meson-efuse.c') diff --git a/drivers/nvmem/meson-efuse.c b/drivers/nvmem/meson-efuse.c new file mode 100644 index 000000000..d7f9ac99a --- /dev/null +++ b/drivers/nvmem/meson-efuse.c @@ -0,0 +1,107 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Amlogic Meson GX eFuse Driver + * + * Copyright (c) 2016 Endless Computers, Inc. + * Author: Carlo Caione + */ + +#include +#include +#include +#include +#include + +#include + +static int meson_efuse_read(void *context, unsigned int offset, + void *val, size_t bytes) +{ + struct meson_sm_firmware *fw = context; + int ret; + + ret = meson_sm_call_read(fw, (u8 *)val, bytes, SM_EFUSE_READ, offset, + bytes, 0, 0, 0); + + return ret < 0 ? ret : 0; +} + +static int meson_efuse_write(void *context, unsigned int offset, + void *val, size_t bytes) +{ + struct meson_sm_firmware *fw = context; + int ret; + + ret = meson_sm_call_write(fw, (u8 *)val, bytes, SM_EFUSE_WRITE, offset, + bytes, 0, 0, 0); + + return ret < 0 ? ret : 0; +} + +static const struct of_device_id meson_efuse_match[] = { + { .compatible = "amlogic,meson-gxbb-efuse", }, + { /* sentinel */ }, +}; +MODULE_DEVICE_TABLE(of, meson_efuse_match); + +static int meson_efuse_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct meson_sm_firmware *fw; + struct nvmem_device *nvmem; + struct nvmem_config *econfig; + struct clk *clk; + unsigned int size; + struct device_node *sm_np __free(device_node) = + of_parse_phandle(pdev->dev.of_node, "secure-monitor", 0); + + if (!sm_np) { + dev_err(&pdev->dev, "no secure-monitor node\n"); + return -ENODEV; + } + + fw = meson_sm_get(sm_np); + if (!fw) + return -EPROBE_DEFER; + + clk = devm_clk_get_enabled(dev, NULL); + if (IS_ERR(clk)) + return dev_err_probe(dev, PTR_ERR(clk), "failed to get efuse gate"); + + if (meson_sm_call(fw, SM_EFUSE_USER_MAX, &size, 0, 0, 0, 0, 0) < 0) { + dev_err(dev, "failed to get max user"); + return -EINVAL; + } + + econfig = devm_kzalloc(dev, sizeof(*econfig), GFP_KERNEL); + if (!econfig) + return -ENOMEM; + + econfig->dev = dev; + econfig->name = dev_name(dev); + econfig->add_legacy_fixed_of_cells = true; + econfig->stride = 1; + econfig->word_size = 1; + econfig->reg_read = meson_efuse_read; + econfig->reg_write = meson_efuse_write; + econfig->size = size; + econfig->priv = fw; + + nvmem = devm_nvmem_register(&pdev->dev, econfig); + + return PTR_ERR_OR_ZERO(nvmem); +} + +static struct platform_driver meson_efuse_driver = { + .probe = meson_efuse_probe, + .driver = { + .name = "meson-efuse", + .of_match_table = meson_efuse_match, + }, +}; + +module_platform_driver(meson_efuse_driver); + +MODULE_AUTHOR("Carlo Caione "); +MODULE_DESCRIPTION("Amlogic Meson GX NVMEM driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1