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/dh_helper.c | 120 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) create mode 100644 crypto/dh_helper.c (limited to 'crypto/dh_helper.c') diff --git a/crypto/dh_helper.c b/crypto/dh_helper.c new file mode 100644 index 000000000..2d4998793 --- /dev/null +++ b/crypto/dh_helper.c @@ -0,0 +1,120 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2016, Intel Corporation + * Authors: Salvatore Benedetto + */ +#include +#include +#include +#include +#include +#include + +#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int)) + +static inline u8 *dh_pack_data(u8 *dst, u8 *end, const void *src, size_t size) +{ + if (!dst || size > end - dst) + return NULL; + memcpy(dst, src, size); + return dst + size; +} + +static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size) +{ + memcpy(dst, src, size); + return src + size; +} + +static inline unsigned int dh_data_size(const struct dh *p) +{ + return p->key_size + p->p_size + p->g_size; +} + +unsigned int crypto_dh_key_len(const struct dh *p) +{ + return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p); +} +EXPORT_SYMBOL_GPL(crypto_dh_key_len); + +int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params) +{ + u8 *ptr = buf; + u8 * const end = ptr + len; + struct kpp_secret secret = { + .type = CRYPTO_KPP_SECRET_TYPE_DH, + .len = len + }; + + if (unlikely(!len)) + return -EINVAL; + + ptr = dh_pack_data(ptr, end, &secret, sizeof(secret)); + ptr = dh_pack_data(ptr, end, ¶ms->key_size, + sizeof(params->key_size)); + ptr = dh_pack_data(ptr, end, ¶ms->p_size, sizeof(params->p_size)); + ptr = dh_pack_data(ptr, end, ¶ms->g_size, sizeof(params->g_size)); + ptr = dh_pack_data(ptr, end, params->key, params->key_size); + ptr = dh_pack_data(ptr, end, params->p, params->p_size); + ptr = dh_pack_data(ptr, end, params->g, params->g_size); + if (ptr != end) + return -EINVAL; + return 0; +} +EXPORT_SYMBOL_GPL(crypto_dh_encode_key); + +int __crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) +{ + const u8 *ptr = buf; + struct kpp_secret secret; + + if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE)) + return -EINVAL; + + ptr = dh_unpack_data(&secret, ptr, sizeof(secret)); + if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH) + return -EINVAL; + + ptr = dh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size)); + ptr = dh_unpack_data(¶ms->p_size, ptr, sizeof(params->p_size)); + ptr = dh_unpack_data(¶ms->g_size, ptr, sizeof(params->g_size)); + if (secret.len != crypto_dh_key_len(params)) + return -EINVAL; + + /* Don't allocate memory. Set pointers to data within + * the given buffer + */ + params->key = (void *)ptr; + params->p = (void *)(ptr + params->key_size); + params->g = (void *)(ptr + params->key_size + params->p_size); + + return 0; +} + +int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) +{ + int err; + + err = __crypto_dh_decode_key(buf, len, params); + if (err) + return err; + + /* + * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since + * some drivers assume otherwise. + */ + if (params->key_size > params->p_size || + params->g_size > params->p_size) + return -EINVAL; + + /* + * Don't permit 'p' to be 0. It's not a prime number, and it's subject + * to corner cases such as 'mod 0' being undefined or + * crypto_kpp_maxsize() returning 0. + */ + if (memchr_inv(params->p, 0, params->p_size) == NULL) + return -EINVAL; + + return 0; +} +EXPORT_SYMBOL_GPL(crypto_dh_decode_key); -- cgit v1.3.1