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/input/input-compat.h | 81 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 drivers/input/input-compat.h (limited to 'drivers/input/input-compat.h') diff --git a/drivers/input/input-compat.h b/drivers/input/input-compat.h new file mode 100644 index 000000000..99c87ceb9 --- /dev/null +++ b/drivers/input/input-compat.h @@ -0,0 +1,81 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _INPUT_COMPAT_H +#define _INPUT_COMPAT_H + +/* + * 32bit compatibility wrappers for the input subsystem. + * + * Very heavily based on evdev.c - Copyright (c) 1999-2002 Vojtech Pavlik + */ + +#include +#include +#include + +#ifdef CONFIG_COMPAT + +struct input_event_compat { + compat_ulong_t sec; + compat_ulong_t usec; + __u16 type; + __u16 code; + __s32 value; +}; + +struct ff_periodic_effect_compat { + __u16 waveform; + __u16 period; + __s16 magnitude; + __s16 offset; + __u16 phase; + + struct ff_envelope envelope; + + __u32 custom_len; + compat_uptr_t custom_data; +}; + +struct ff_effect_compat { + __u16 type; + __s16 id; + __u16 direction; + struct ff_trigger trigger; + struct ff_replay replay; + + union { + struct ff_constant_effect constant; + struct ff_ramp_effect ramp; + struct ff_periodic_effect_compat periodic; + struct ff_condition_effect condition[2]; /* One for each axis */ + struct ff_rumble_effect rumble; + } u; +}; + +static inline size_t input_event_size(void) +{ + return (in_compat_syscall() && !COMPAT_USE_64BIT_TIME) ? + sizeof(struct input_event_compat) : sizeof(struct input_event); +} + +#else + +static inline size_t input_event_size(void) +{ + return sizeof(struct input_event); +} + +#endif /* CONFIG_COMPAT */ + +int input_event_from_user(const char __user *buffer, + struct input_event *event); + +int input_event_to_user(char __user *buffer, + const struct input_event *event); + +int input_ff_effect_from_user(const char __user *buffer, size_t size, + struct ff_effect *effect); + +int input_bits_to_string(char *buf, int buf_size, unsigned long bits, + bool skip_empty); + +#endif /* _INPUT_COMPAT_H */ -- cgit v1.3.1