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/bcm63xx.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 102 insertions(+) create mode 100644 drivers/net/phy/bcm63xx.c (limited to 'drivers/net/phy/bcm63xx.c') diff --git a/drivers/net/phy/bcm63xx.c b/drivers/net/phy/bcm63xx.c new file mode 100644 index 000000000..b46a736a3 --- /dev/null +++ b/drivers/net/phy/bcm63xx.c @@ -0,0 +1,102 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Driver for Broadcom 63xx SOCs integrated PHYs + */ +#include "bcm-phy-lib.h" +#include +#include + +#define MII_BCM63XX_IR 0x1a /* interrupt register */ +#define MII_BCM63XX_IR_EN 0x4000 /* global interrupt enable */ +#define MII_BCM63XX_IR_DUPLEX 0x0800 /* duplex changed */ +#define MII_BCM63XX_IR_SPEED 0x0400 /* speed changed */ +#define MII_BCM63XX_IR_LINK 0x0200 /* link changed */ +#define MII_BCM63XX_IR_GMASK 0x0100 /* global interrupt mask */ + +MODULE_DESCRIPTION("Broadcom 63xx internal PHY driver"); +MODULE_AUTHOR("Maxime Bizon "); +MODULE_LICENSE("GPL"); + +static int bcm63xx_config_intr(struct phy_device *phydev) +{ + int reg, err; + + reg = phy_read(phydev, MII_BCM63XX_IR); + if (reg < 0) + return reg; + + if (phydev->interrupts == PHY_INTERRUPT_ENABLED) { + err = bcm_phy_ack_intr(phydev); + if (err) + return err; + + reg &= ~MII_BCM63XX_IR_GMASK; + err = phy_write(phydev, MII_BCM63XX_IR, reg); + } else { + reg |= MII_BCM63XX_IR_GMASK; + err = phy_write(phydev, MII_BCM63XX_IR, reg); + if (err) + return err; + + err = bcm_phy_ack_intr(phydev); + } + + return err; +} + +static int bcm63xx_config_init(struct phy_device *phydev) +{ + int reg, err; + + /* ASYM_PAUSE bit is marked RO in datasheet, so don't cheat */ + linkmode_set_bit(ETHTOOL_LINK_MODE_Pause_BIT, phydev->supported); + + reg = phy_read(phydev, MII_BCM63XX_IR); + if (reg < 0) + return reg; + + /* Mask interrupts globally. */ + reg |= MII_BCM63XX_IR_GMASK; + err = phy_write(phydev, MII_BCM63XX_IR, reg); + if (err < 0) + return err; + + /* Unmask events we are interested in */ + reg = ~(MII_BCM63XX_IR_DUPLEX | + MII_BCM63XX_IR_SPEED | + MII_BCM63XX_IR_LINK) | + MII_BCM63XX_IR_EN; + return phy_write(phydev, MII_BCM63XX_IR, reg); +} + +static struct phy_driver bcm63xx_driver[] = { +{ + .phy_id = 0x00406000, + .phy_id_mask = 0xfffffc00, + .name = "Broadcom BCM63XX (1)", + /* PHY_BASIC_FEATURES */ + .flags = PHY_IS_INTERNAL, + .config_init = bcm63xx_config_init, + .config_intr = bcm63xx_config_intr, + .handle_interrupt = bcm_phy_handle_interrupt, +}, { + /* same phy as above, with just a different OUI */ + .phy_id = 0x002bdc00, + .phy_id_mask = 0xfffffc00, + .name = "Broadcom BCM63XX (2)", + /* PHY_BASIC_FEATURES */ + .flags = PHY_IS_INTERNAL, + .config_init = bcm63xx_config_init, + .config_intr = bcm63xx_config_intr, + .handle_interrupt = bcm_phy_handle_interrupt, +} }; + +module_phy_driver(bcm63xx_driver); + +static const struct mdio_device_id __maybe_unused bcm63xx_tbl[] = { + { 0x00406000, 0xfffffc00 }, + { 0x002bdc00, 0xfffffc00 }, + { } +}; + +MODULE_DEVICE_TABLE(mdio, bcm63xx_tbl); -- cgit v1.3.1