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/rcar-efuse.c | 142 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 142 insertions(+) create mode 100644 drivers/nvmem/rcar-efuse.c (limited to 'drivers/nvmem/rcar-efuse.c') diff --git a/drivers/nvmem/rcar-efuse.c b/drivers/nvmem/rcar-efuse.c new file mode 100644 index 000000000..b94ff83b7 --- /dev/null +++ b/drivers/nvmem/rcar-efuse.c @@ -0,0 +1,142 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Renesas R-Car E-FUSE/OTP Driver + * + * Copyright (C) 2024 Glider bv + */ + +#include +#include +#include +#include +#include +#include +#include + +struct rcar_fuse { + struct nvmem_keepout keepouts[2]; + struct nvmem_device *nvmem; + struct device *dev; + void __iomem *base; +}; + +struct rcar_fuse_data { + unsigned int bank; /* 0: PFC + E-FUSE, 1: OPT_MEM + E-FUSE */ + unsigned int start; /* inclusive */ + unsigned int end; /* exclusive */ +}; + +static int rcar_fuse_reg_read(void *priv, unsigned int offset, void *val, + size_t bytes) +{ + struct rcar_fuse *fuse = priv; + int ret; + + ret = pm_runtime_resume_and_get(fuse->dev); + if (ret < 0) + return ret; + + __ioread32_copy(val, fuse->base + offset, bytes / 4); + + pm_runtime_put(fuse->dev); + + return 0; +} + +static int rcar_fuse_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + const struct rcar_fuse_data *data = device_get_match_data(dev); + struct nvmem_config config = { + .dev = dev, + .name = "rcar-fuse", + .id = NVMEM_DEVID_NONE, + .owner = THIS_MODULE, + .type = NVMEM_TYPE_OTP, + .read_only = true, + .root_only = true, + .reg_read = rcar_fuse_reg_read, + .word_size = 4, + .stride = 4, + }; + struct rcar_fuse *fuse; + struct resource *res; + int ret; + + ret = devm_pm_runtime_enable(dev); + if (ret < 0) + return ret; + + fuse = devm_kzalloc(dev, sizeof(*fuse), GFP_KERNEL); + if (!fuse) + return -ENOMEM; + + fuse->base = devm_platform_get_and_ioremap_resource(pdev, data->bank, + &res); + if (IS_ERR(fuse->base)) + return PTR_ERR(fuse->base); + + fuse->dev = dev; + fuse->keepouts[0].start = 0; + fuse->keepouts[0].end = data->start; + fuse->keepouts[1].start = data->end; + fuse->keepouts[1].end = resource_size(res); + + config.keepout = fuse->keepouts; + config.nkeepout = ARRAY_SIZE(fuse->keepouts); + config.size = resource_size(res); + config.priv = fuse; + + fuse->nvmem = devm_nvmem_register(dev, &config); + if (IS_ERR(fuse->nvmem)) + return dev_err_probe(dev, PTR_ERR(fuse->nvmem), + "Failed to register NVMEM device\n"); + + return 0; +} + +static const struct rcar_fuse_data rcar_fuse_v3u = { + .bank = 0, + .start = 0x0c0, + .end = 0x0e8, +}; + +static const struct rcar_fuse_data rcar_fuse_s4 = { + .bank = 0, + .start = 0x0c0, + .end = 0x14c, +}; + +static const struct rcar_fuse_data rcar_fuse_v4h = { + .bank = 1, + .start = 0x100, + .end = 0x1a0, +}; + +static const struct rcar_fuse_data rcar_fuse_v4m = { + .bank = 1, + .start = 0x100, + .end = 0x110, +}; + +static const struct of_device_id rcar_fuse_match[] = { + { .compatible = "renesas,r8a779a0-efuse", .data = &rcar_fuse_v3u }, + { .compatible = "renesas,r8a779f0-efuse", .data = &rcar_fuse_s4 }, + { .compatible = "renesas,r8a779g0-otp", .data = &rcar_fuse_v4h }, + { .compatible = "renesas,r8a779h0-otp", .data = &rcar_fuse_v4m }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, rcar_fuse_match); + +static struct platform_driver rcar_fuse_driver = { + .probe = rcar_fuse_probe, + .driver = { + .name = "rcar_fuse", + .of_match_table = rcar_fuse_match, + }, +}; +module_platform_driver(rcar_fuse_driver); + +MODULE_DESCRIPTION("Renesas R-Car E-FUSE/OTP driver"); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Geert Uytterhoeven"); -- cgit v1.3.1