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/crypto/caam/dpseci-debugfs.c | 60 ++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 drivers/crypto/caam/dpseci-debugfs.c (limited to 'drivers/crypto/caam/dpseci-debugfs.c') diff --git a/drivers/crypto/caam/dpseci-debugfs.c b/drivers/crypto/caam/dpseci-debugfs.c new file mode 100644 index 000000000..020a9d8a8 --- /dev/null +++ b/drivers/crypto/caam/dpseci-debugfs.c @@ -0,0 +1,60 @@ +// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause) +/* Copyright 2019 NXP */ + +#include +#include +#include +#include "dpseci-debugfs.h" + +static int dpseci_dbg_fqs_show(struct seq_file *file, void *offset) +{ + struct dpaa2_caam_priv *priv = file->private; + u32 fqid, fcnt, bcnt; + int i, err; + + seq_printf(file, "FQ stats for %s:\n", dev_name(priv->dev)); + seq_printf(file, "%s%16s%16s\n", + "Rx-VFQID", + "Pending frames", + "Pending bytes"); + + for (i = 0; i < priv->num_pairs; i++) { + fqid = priv->rx_queue_attr[i].fqid; + err = dpaa2_io_query_fq_count(NULL, fqid, &fcnt, &bcnt); + if (err) + continue; + + seq_printf(file, "%5d%16u%16u\n", fqid, fcnt, bcnt); + } + + seq_printf(file, "%s%16s%16s\n", + "Tx-VFQID", + "Pending frames", + "Pending bytes"); + + for (i = 0; i < priv->num_pairs; i++) { + fqid = priv->tx_queue_attr[i].fqid; + err = dpaa2_io_query_fq_count(NULL, fqid, &fcnt, &bcnt); + if (err) + continue; + + seq_printf(file, "%5d%16u%16u\n", fqid, fcnt, bcnt); + } + + return 0; +} + +DEFINE_SHOW_ATTRIBUTE(dpseci_dbg_fqs); + +void dpaa2_dpseci_debugfs_init(struct dpaa2_caam_priv *priv) +{ + priv->dfs_root = debugfs_create_dir(dev_name(priv->dev), NULL); + + debugfs_create_file("fq_stats", 0444, priv->dfs_root, priv, + &dpseci_dbg_fqs_fops); +} + +void dpaa2_dpseci_debugfs_exit(struct dpaa2_caam_priv *priv) +{ + debugfs_remove_recursive(priv->dfs_root); +} -- cgit v1.3.1