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/pse-pd/Kconfig | 83 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) create mode 100644 drivers/net/pse-pd/Kconfig (limited to 'drivers/net/pse-pd/Kconfig') diff --git a/drivers/net/pse-pd/Kconfig b/drivers/net/pse-pd/Kconfig new file mode 100644 index 000000000..a0f2ae668 --- /dev/null +++ b/drivers/net/pse-pd/Kconfig @@ -0,0 +1,83 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +# Ethernet Power Sourcing Equipment drivers +# + +menuconfig PSE_CONTROLLER + bool "Ethernet Power Sourcing Equipment Support" + depends on REGULATOR + help + Generic Power Sourcing Equipment Controller support. + + If unsure, say no. + +if PSE_CONTROLLER + +config PSE_REALTEK_MCU + tristate + help + Shared core for the Realtek PSE MCU driver. This is selected + automatically by the transport options below. + +config PSE_REALTEK_MCU_I2C + tristate "Realtek PSE MCU driver (I2C transport)" + depends on I2C + select PSE_REALTEK_MCU + help + Driver for the microcontroller (MCU) that fronts the PSE + hardware on various Realtek-based managed switches, attached + via I2C/SMBus. The MCU exposes a message-based protocol; the actual + PSE silicon is not accessed directly. To compile this driver as a + module, choose M here: the module will be called realtek-pse-mcu-i2c. + +config PSE_REALTEK_MCU_UART + tristate "Realtek PSE MCU driver (UART transport)" + depends on SERIAL_DEV_BUS + select PSE_REALTEK_MCU + help + Driver for the microcontroller (MCU) that fronts the PSE + hardware on various Realtek-based managed switches, attached + via UART. The MCU exposes a message-based protocol; the actual PSE + silicon is not accessed directly. To compile this driver as a + module, choose M here: the module will be called realtek-pse-mcu-uart. + +config PSE_REGULATOR + tristate "Regulator based PSE controller" + help + This module provides support for simple regulator based Ethernet Power + Sourcing Equipment without automatic classification support. For + example for basic implementation of PoDL (802.3bu) specification. + +config PSE_PD692X0 + tristate "PD692X0 PSE controller" + depends on I2C + select FW_LOADER + select FW_UPLOAD + help + This module provides support for PD692x0 regulator based Ethernet + Power Sourcing Equipment. + + To compile this driver as a module, choose M here: the + module will be called pd692x0. + +config PSE_SI3474 + tristate "Si3474 PSE controller" + depends on I2C + help + This module provides support for Si3474 regulator based Ethernet + Power Sourcing Equipment. + Only 4-pair PSE configurations are supported. + + To compile this driver as a module, choose M here: the + module will be called si3474. + +config PSE_TPS23881 + tristate "TPS23881 PSE controller" + depends on I2C + help + This module provides support for TPS23881 regulator based Ethernet + Power Sourcing Equipment. + + To compile this driver as a module, choose M here: the + module will be called tps23881. +endif -- cgit v1.3.1