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/crypto/internal/engine.h | 58 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 include/crypto/internal/engine.h (limited to 'include/crypto/internal/engine.h') diff --git a/include/crypto/internal/engine.h b/include/crypto/internal/engine.h new file mode 100644 index 000000000..6a1d27880 --- /dev/null +++ b/include/crypto/internal/engine.h @@ -0,0 +1,58 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Crypto engine API + * + * Copyright (c) 2016 Baolin Wang + * Copyright (c) 2023 Herbert Xu + */ +#ifndef _CRYPTO_INTERNAL_ENGINE_H +#define _CRYPTO_INTERNAL_ENGINE_H + +#include +#include +#include +#include +#include + +#define ENGINE_NAME_LEN 30 + +struct device; + +/* + * struct crypto_engine - crypto hardware engine + * @name: the engine name + * @busy: request pump is busy + * @running: the engine is on working + * @retry_support: indication that the hardware allows re-execution + * of a failed backlog request + * crypto-engine, in head position to keep order + * @rt: whether this queue is set to run as a realtime task + * @list: link with the global crypto engine list + * @queue_lock: spinlock to synchronise access to request queue + * @queue: the crypto queue of the engine + * @kworker: kthread worker struct for request pump + * @pump_requests: work struct for scheduling work to the request pump + * @priv_data: the engine private data + * @cur_req: the current request which is on processing + */ +struct crypto_engine { + char name[ENGINE_NAME_LEN]; + bool busy; + bool running; + + bool retry_support; + bool rt; + + struct list_head list; + spinlock_t queue_lock; + struct crypto_queue queue __guarded_by(&queue_lock); + struct device *dev; + + struct kthread_worker *kworker; + struct kthread_work pump_requests; + + void *priv_data; + struct crypto_async_request *cur_req; +}; + +#endif -- cgit v1.3.1