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/usb/chipidea/trace.h | 92 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 drivers/usb/chipidea/trace.h (limited to 'drivers/usb/chipidea/trace.h') diff --git a/drivers/usb/chipidea/trace.h b/drivers/usb/chipidea/trace.h new file mode 100644 index 000000000..1875419cd --- /dev/null +++ b/drivers/usb/chipidea/trace.h @@ -0,0 +1,92 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Trace support header file for device mode + * + * Copyright (C) 2020 NXP + * + * Author: Peter Chen + */ + +#undef TRACE_SYSTEM +#define TRACE_SYSTEM chipidea + +#if !defined(__LINUX_CHIPIDEA_TRACE) || defined(TRACE_HEADER_MULTI_READ) +#define __LINUX_CHIPIDEA_TRACE + +#include +#include +#include +#include "ci.h" +#include "udc.h" + +#define CHIPIDEA_MSG_MAX 500 + +void ci_log(struct ci_hdrc *ci, const char *fmt, ...); + +TRACE_EVENT(ci_log, + TP_PROTO(struct ci_hdrc *ci, struct va_format *vaf), + TP_ARGS(ci, vaf), + TP_STRUCT__entry( + __string(name, dev_name(ci->dev)) + __vstring(msg, vaf->fmt, vaf->va) + ), + TP_fast_assign( + __assign_str(name); + __assign_vstr(msg, vaf->fmt, vaf->va); + ), + TP_printk("%s: %s", __get_str(name), __get_str(msg)) +); + +DECLARE_EVENT_CLASS(ci_log_trb, + TP_PROTO(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq, struct td_node *td), + TP_ARGS(hwep, hwreq, td), + TP_STRUCT__entry( + __string(name, hwep->name) + __field(struct td_node *, td) + __field(struct usb_request *, req) + __field(dma_addr_t, dma) + __field(s32, td_remaining_size) + __field(u32, next) + __field(u32, token) + __field(u32, type) + ), + TP_fast_assign( + __assign_str(name); + __entry->req = &hwreq->req; + __entry->td = td; + __entry->dma = td->dma; + __entry->td_remaining_size = td->td_remaining_size; + __entry->next = le32_to_cpu(td->ptr->next); + __entry->token = le32_to_cpu(td->ptr->token); + __entry->type = usb_endpoint_type(hwep->ep.desc); + ), + TP_printk("%s: req: %p, td: %p, td_dma_address: %pad, remaining_size: %d, " + "next: %x, total bytes: %d, status: %lx", + __get_str(name), __entry->req, __entry->td, &__entry->dma, + __entry->td_remaining_size, __entry->next, + (int)((__entry->token & TD_TOTAL_BYTES) >> __ffs(TD_TOTAL_BYTES)), + __entry->token & TD_STATUS + ) +); + +DEFINE_EVENT(ci_log_trb, ci_prepare_td, + TP_PROTO(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq, struct td_node *td), + TP_ARGS(hwep, hwreq, td) +); + +DEFINE_EVENT(ci_log_trb, ci_complete_td, + TP_PROTO(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq, struct td_node *td), + TP_ARGS(hwep, hwreq, td) +); + +#endif /* __LINUX_CHIPIDEA_TRACE */ + +/* this part must be outside header guard */ + +#undef TRACE_INCLUDE_PATH +#define TRACE_INCLUDE_PATH . + +#undef TRACE_INCLUDE_FILE +#define TRACE_INCLUDE_FILE trace + +#include -- cgit v1.3.1