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/mfd/intel-lpss.h | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 drivers/mfd/intel-lpss.h (limited to 'drivers/mfd/intel-lpss.h') diff --git a/drivers/mfd/intel-lpss.h b/drivers/mfd/intel-lpss.h new file mode 100644 index 000000000..6f8f668f4 --- /dev/null +++ b/drivers/mfd/intel-lpss.h @@ -0,0 +1,47 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Intel LPSS core support. + * + * Copyright (C) 2015, Intel Corporation + * + * Authors: Andy Shevchenko + * Mika Westerberg + */ + +#ifndef __MFD_INTEL_LPSS_H +#define __MFD_INTEL_LPSS_H + +#include +#include + +/* + * Some DSDTs have an unused GEXP ACPI device conflicting with I2C4 resources. + * Set to ignore resource conflicts with ACPI declared SystemMemory regions. + */ +#define QUIRK_IGNORE_RESOURCE_CONFLICTS BIT(0) +/* + * Some devices have misconfigured clock divider due to a firmware bug. + * Set this to force the clock divider to 1:1 ratio. + */ +#define QUIRK_CLOCK_DIVIDER_UNITY BIT(1) + +struct device; +struct resource; +struct software_node; + +struct intel_lpss_platform_info { + struct resource *mem; + int irq; + unsigned int quirks; + unsigned long clk_rate; + const char *clk_con_id; + const struct software_node *swnode; +}; + +int intel_lpss_probe(struct device *dev, + const struct intel_lpss_platform_info *info); +void intel_lpss_remove(struct device *dev); + +extern const struct dev_pm_ops intel_lpss_pm_ops; + +#endif /* __MFD_INTEL_LPSS_H */ -- cgit v1.3.1