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/phy-caps.h | 70 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) create mode 100644 drivers/net/phy/phy-caps.h (limited to 'drivers/net/phy/phy-caps.h') diff --git a/drivers/net/phy/phy-caps.h b/drivers/net/phy/phy-caps.h new file mode 100644 index 000000000..421088e6f --- /dev/null +++ b/drivers/net/phy/phy-caps.h @@ -0,0 +1,70 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * link caps internal header, for link modes <-> capabilities <-> interfaces + * conversions. + */ + +#ifndef __PHY_CAPS_H +#define __PHY_CAPS_H + +#include +#include + +enum { + LINK_CAPA_10HD = 0, + LINK_CAPA_10FD, + LINK_CAPA_100HD, + LINK_CAPA_100FD, + LINK_CAPA_1000HD, + LINK_CAPA_1000FD, + LINK_CAPA_2500FD, + LINK_CAPA_5000FD, + LINK_CAPA_10000FD, + LINK_CAPA_20000FD, + LINK_CAPA_25000FD, + LINK_CAPA_40000FD, + LINK_CAPA_50000FD, + LINK_CAPA_56000FD, + LINK_CAPA_80000FD, + LINK_CAPA_100000FD, + LINK_CAPA_200000FD, + LINK_CAPA_400000FD, + LINK_CAPA_800000FD, + LINK_CAPA_1600000FD, + + __LINK_CAPA_MAX, +}; + +#define LINK_CAPA_ALL GENMASK((__LINK_CAPA_MAX - 1), 0) + +struct link_capabilities { + int speed; + unsigned int duplex; + __ETHTOOL_DECLARE_LINK_MODE_MASK(linkmodes); +}; + +int __init phy_caps_init(void); + +size_t phy_caps_speeds(unsigned int *speeds, size_t size, + unsigned long *linkmodes); +void phy_caps_linkmode_max_speed(u32 max_speed, unsigned long *linkmodes); +bool phy_caps_valid(int speed, int duplex, const unsigned long *linkmodes); +void phy_caps_linkmodes(unsigned long caps, unsigned long *linkmodes); +unsigned long phy_caps_from_interface(phy_interface_t interface); + +const struct link_capabilities * +phy_caps_lookup_by_linkmode(const unsigned long *linkmodes); + +const struct link_capabilities * +phy_caps_lookup_by_linkmode_rev(const unsigned long *linkmodes, bool fdx_only); + +const struct link_capabilities * +phy_caps_lookup(int speed, unsigned int duplex, const unsigned long *supported, + bool exact); + +void phy_caps_medium_get_supported(unsigned long *supported, + enum ethtool_link_medium medium, + int lanes); +u32 phy_caps_mediums_from_linkmodes(unsigned long *linkmodes); + +#endif /* __PHY_CAPS_H */ -- cgit v1.3.1