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 --- crypto/proc.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 103 insertions(+) create mode 100644 crypto/proc.c (limited to 'crypto/proc.c') diff --git a/crypto/proc.c b/crypto/proc.c new file mode 100644 index 000000000..5fb9fe86d --- /dev/null +++ b/crypto/proc.c @@ -0,0 +1,103 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Scatterlist Cryptographic API. + * + * Procfs information. + * + * Copyright (c) 2002 James Morris + * Copyright (c) 2005 Herbert Xu + */ + +#include +#include +#include +#include +#include /* for module_name() */ +#include +#include +#include +#include "internal.h" + +static void *c_start(struct seq_file *m, loff_t *pos) + __acquires_shared(&crypto_alg_sem) +{ + down_read(&crypto_alg_sem); + return seq_list_start(&crypto_alg_list, *pos); +} + +static void *c_next(struct seq_file *m, void *p, loff_t *pos) + __must_hold_shared(&crypto_alg_sem) +{ + return seq_list_next(p, &crypto_alg_list, pos); +} + +static void c_stop(struct seq_file *m, void *p) + __releases_shared(&crypto_alg_sem) +{ + up_read(&crypto_alg_sem); +} + +static int c_show(struct seq_file *m, void *p) +{ + struct crypto_alg *alg = list_entry(p, struct crypto_alg, cra_list); + + seq_printf(m, "name : %s\n", alg->cra_name); + seq_printf(m, "driver : %s\n", alg->cra_driver_name); + seq_printf(m, "module : %s\n", module_name(alg->cra_module)); + seq_printf(m, "priority : %d\n", alg->cra_priority); + seq_printf(m, "refcnt : %u\n", refcount_read(&alg->cra_refcnt)); + seq_printf(m, "selftest : %s\n", + (alg->cra_flags & CRYPTO_ALG_TESTED) ? + "passed" : "unknown"); + seq_printf(m, "internal : %s\n", + str_yes_no(alg->cra_flags & CRYPTO_ALG_INTERNAL)); + if (fips_enabled) + seq_printf(m, "fips : %s\n", + str_no_yes(alg->cra_flags & CRYPTO_ALG_FIPS_INTERNAL)); + + if (alg->cra_flags & CRYPTO_ALG_LARVAL) { + seq_printf(m, "type : larval\n"); + seq_printf(m, "flags : 0x%x\n", alg->cra_flags); + goto out; + } + + if (alg->cra_type && alg->cra_type->show) { + alg->cra_type->show(m, alg); + goto out; + } + + switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) { + case CRYPTO_ALG_TYPE_CIPHER: + seq_printf(m, "type : cipher\n"); + seq_printf(m, "blocksize : %u\n", alg->cra_blocksize); + seq_printf(m, "min keysize : %u\n", + alg->cra_cipher.cia_min_keysize); + seq_printf(m, "max keysize : %u\n", + alg->cra_cipher.cia_max_keysize); + break; + default: + seq_printf(m, "type : unknown\n"); + break; + } + +out: + seq_putc(m, '\n'); + return 0; +} + +static const struct seq_operations crypto_seq_ops = { + .start = c_start, + .next = c_next, + .stop = c_stop, + .show = c_show +}; + +void __init crypto_init_proc(void) +{ + proc_create_seq("crypto", 0, NULL, &crypto_seq_ops); +} + +void __exit crypto_exit_proc(void) +{ + remove_proc_entry("crypto", NULL); +} -- cgit v1.3.1