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/versatile/clk-versatile.c | 98 +++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) create mode 100644 drivers/clk/versatile/clk-versatile.c (limited to 'drivers/clk/versatile/clk-versatile.c') diff --git a/drivers/clk/versatile/clk-versatile.c b/drivers/clk/versatile/clk-versatile.c new file mode 100644 index 000000000..8ed7a179f --- /dev/null +++ b/drivers/clk/versatile/clk-versatile.c @@ -0,0 +1,98 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Clock driver for the ARM Integrator/AP, Integrator/CP, Versatile AB and + * Versatile PB boards. + * Copyright (C) 2012 Linus Walleij + */ +#include +#include +#include +#include + +#include "icst.h" +#include "clk-icst.h" + +#define INTEGRATOR_HDR_LOCK_OFFSET 0x14 + +#define VERSATILE_SYS_OSCCLCD_OFFSET 0x1c +#define VERSATILE_SYS_LOCK_OFFSET 0x20 + +/* Base offset for the core module */ +static void __iomem *cm_base; + +static const struct icst_params cp_auxosc_params = { + .vco_max = ICST525_VCO_MAX_5V, + .vco_min = ICST525_VCO_MIN, + .vd_min = 8, + .vd_max = 263, + .rd_min = 3, + .rd_max = 65, + .s2div = icst525_s2div, + .idx2s = icst525_idx2s, +}; + +static const struct clk_icst_desc cm_auxosc_desc __initconst = { + .params = &cp_auxosc_params, + .vco_offset = 0x1c, + .lock_offset = INTEGRATOR_HDR_LOCK_OFFSET, +}; + +static const struct icst_params versatile_auxosc_params = { + .vco_max = ICST307_VCO_MAX, + .vco_min = ICST307_VCO_MIN, + .vd_min = 4 + 8, + .vd_max = 511 + 8, + .rd_min = 1 + 2, + .rd_max = 127 + 2, + .s2div = icst307_s2div, + .idx2s = icst307_idx2s, +}; + +static const struct clk_icst_desc versatile_auxosc_desc __initconst = { + .params = &versatile_auxosc_params, + .vco_offset = VERSATILE_SYS_OSCCLCD_OFFSET, + .lock_offset = VERSATILE_SYS_LOCK_OFFSET, +}; +static void __init cm_osc_setup(struct device_node *np, + const struct clk_icst_desc *desc) +{ + struct clk *clk; + const char *clk_name = np->name; + const char *parent_name; + + if (!cm_base) { + /* Remap the core module base if not done yet */ + struct device_node *parent; + + parent = of_get_parent(np); + if (!parent) { + pr_err("no parent on core module clock\n"); + return; + } + cm_base = of_iomap(parent, 0); + of_node_put(parent); + if (!cm_base) { + pr_err("could not remap core module base\n"); + return; + } + } + + parent_name = of_clk_get_parent_name(np, 0); + clk = icst_clk_register(NULL, desc, clk_name, parent_name, cm_base); + if (!IS_ERR(clk)) + of_clk_add_provider(np, of_clk_src_simple_get, clk); +} + +static void __init of_integrator_cm_osc_setup(struct device_node *np) +{ + cm_osc_setup(np, &cm_auxosc_desc); +} +CLK_OF_DECLARE(integrator_cm_auxosc_clk, + "arm,integrator-cm-auxosc", of_integrator_cm_osc_setup); + +static void __init of_versatile_cm_osc_setup(struct device_node *np) +{ + cm_osc_setup(np, &versatile_auxosc_desc); +} +CLK_OF_DECLARE(versatile_cm_auxosc_clk, + "arm,versatile-cm-auxosc", of_versatile_cm_osc_setup); -- cgit v1.3.1