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/net/phy/cicada.c | 154 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 154 insertions(+) create mode 100644 drivers/net/phy/cicada.c (limited to 'drivers/net/phy/cicada.c') diff --git a/drivers/net/phy/cicada.c b/drivers/net/phy/cicada.c new file mode 100644 index 000000000..d87cf8b94 --- /dev/null +++ b/drivers/net/phy/cicada.c @@ -0,0 +1,154 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * drivers/net/phy/cicada.c + * + * Driver for Cicada PHYs + * + * Author: Andy Fleming + * + * Copyright (c) 2004 Freescale Semiconductor, Inc. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +/* Cicada Extended Control Register 1 */ +#define MII_CIS8201_EXT_CON1 0x17 +#define MII_CIS8201_EXTCON1_INIT 0x0000 + +/* Cicada Interrupt Mask Register */ +#define MII_CIS8201_IMASK 0x19 +#define MII_CIS8201_IMASK_IEN 0x8000 +#define MII_CIS8201_IMASK_SPEED 0x4000 +#define MII_CIS8201_IMASK_LINK 0x2000 +#define MII_CIS8201_IMASK_DUPLEX 0x1000 +#define MII_CIS8201_IMASK_MASK 0xf000 + +/* Cicada Interrupt Status Register */ +#define MII_CIS8201_ISTAT 0x1a +#define MII_CIS8201_ISTAT_STATUS 0x8000 +#define MII_CIS8201_ISTAT_SPEED 0x4000 +#define MII_CIS8201_ISTAT_LINK 0x2000 +#define MII_CIS8201_ISTAT_DUPLEX 0x1000 + +/* Cicada Auxiliary Control/Status Register */ +#define MII_CIS8201_AUX_CONSTAT 0x1c +#define MII_CIS8201_AUXCONSTAT_INIT 0x0004 +#define MII_CIS8201_AUXCONSTAT_DUPLEX 0x0020 +#define MII_CIS8201_AUXCONSTAT_SPEED 0x0018 +#define MII_CIS8201_AUXCONSTAT_GBIT 0x0010 +#define MII_CIS8201_AUXCONSTAT_100 0x0008 + +MODULE_DESCRIPTION("Cicadia PHY driver"); +MODULE_AUTHOR("Andy Fleming"); +MODULE_LICENSE("GPL"); + +static int cis820x_config_init(struct phy_device *phydev) +{ + int err; + + err = phy_write(phydev, MII_CIS8201_AUX_CONSTAT, + MII_CIS8201_AUXCONSTAT_INIT); + + if (err < 0) + return err; + + err = phy_write(phydev, MII_CIS8201_EXT_CON1, + MII_CIS8201_EXTCON1_INIT); + + return err; +} + +static int cis820x_ack_interrupt(struct phy_device *phydev) +{ + int err = phy_read(phydev, MII_CIS8201_ISTAT); + + return (err < 0) ? err : 0; +} + +static int cis820x_config_intr(struct phy_device *phydev) +{ + int err; + + if (phydev->interrupts == PHY_INTERRUPT_ENABLED) { + err = cis820x_ack_interrupt(phydev); + if (err) + return err; + + err = phy_write(phydev, MII_CIS8201_IMASK, + MII_CIS8201_IMASK_MASK); + } else { + err = phy_write(phydev, MII_CIS8201_IMASK, 0); + if (err) + return err; + + err = cis820x_ack_interrupt(phydev); + } + + return err; +} + +static irqreturn_t cis820x_handle_interrupt(struct phy_device *phydev) +{ + int irq_status; + + irq_status = phy_read(phydev, MII_CIS8201_ISTAT); + if (irq_status < 0) { + phy_error(phydev); + return IRQ_NONE; + } + + if (!(irq_status & MII_CIS8201_IMASK_MASK)) + return IRQ_NONE; + + phy_trigger_machine(phydev); + + return IRQ_HANDLED; +} + +/* Cicada 8201, a.k.a Vitesse VSC8201 */ +static struct phy_driver cis820x_driver[] = { +{ + .phy_id = 0x000fc410, + .name = "Cicada Cis8201", + .phy_id_mask = 0x000ffff0, + /* PHY_GBIT_FEATURES */ + .config_init = &cis820x_config_init, + .config_intr = &cis820x_config_intr, + .handle_interrupt = &cis820x_handle_interrupt, +}, { + .phy_id = 0x000fc440, + .name = "Cicada Cis8204", + .phy_id_mask = 0x000fffc0, + /* PHY_GBIT_FEATURES */ + .config_init = &cis820x_config_init, + .config_intr = &cis820x_config_intr, + .handle_interrupt = &cis820x_handle_interrupt, +} }; + +module_phy_driver(cis820x_driver); + +static const struct mdio_device_id __maybe_unused cicada_tbl[] = { + { 0x000fc410, 0x000ffff0 }, + { 0x000fc440, 0x000fffc0 }, + { } +}; + +MODULE_DEVICE_TABLE(mdio, cicada_tbl); -- cgit v1.3.1