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 --- include/net/ax88796.h | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 include/net/ax88796.h (limited to 'include/net/ax88796.h') diff --git a/include/net/ax88796.h b/include/net/ax88796.h new file mode 100644 index 000000000..303100f08 --- /dev/null +++ b/include/net/ax88796.h @@ -0,0 +1,46 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* include/net/ax88796.h + * + * Copyright 2005 Simtec Electronics + * Ben Dooks +*/ + +#ifndef __NET_AX88796_PLAT_H +#define __NET_AX88796_PLAT_H + +#include + +struct sk_buff; +struct net_device; +struct platform_device; + +#define AXFLG_HAS_EEPROM (1<<0) +#define AXFLG_MAC_FROMDEV (1<<1) /* device already has MAC */ +#define AXFLG_HAS_93CX6 (1<<2) /* use eeprom_93cx6 driver */ +#define AXFLG_MAC_FROMPLATFORM (1<<3) /* MAC given by platform data */ + +struct ax_plat_data { + unsigned int flags; + unsigned char wordlength; /* 1 or 2 */ + unsigned char dcr_val; /* default value for DCR */ + unsigned char rcr_val; /* default value for RCR */ + unsigned char gpoc_val; /* default value for GPOC */ + u32 *reg_offsets; /* register offsets */ + u8 *mac_addr; /* MAC addr (only used when + AXFLG_MAC_FROMPLATFORM is used */ + + /* uses default ax88796 buffer if set to NULL */ + void (*block_output)(struct net_device *dev, int count, + const unsigned char *buf, int star_page); + void (*block_input)(struct net_device *dev, int count, + struct sk_buff *skb, int ring_offset); + /* returns nonzero if a pending interrupt request might be caused by + * the ax88796. Handles all interrupts if set to NULL + */ + int (*check_irq)(struct platform_device *pdev); +}; + +/* exported from ax88796.c for xsurf100.c */ +extern void ax_NS8390_reinit(struct net_device *dev); + +#endif /* __NET_AX88796_PLAT_H */ -- cgit v1.3.1