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 --- net/rxrpc/server_key.c | 215 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 215 insertions(+) create mode 100644 net/rxrpc/server_key.c (limited to 'net/rxrpc/server_key.c') diff --git a/net/rxrpc/server_key.c b/net/rxrpc/server_key.c new file mode 100644 index 000000000..3efe104b1 --- /dev/null +++ b/net/rxrpc/server_key.c @@ -0,0 +1,215 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* RxRPC key management + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * RxRPC keys should have a description of describing their purpose: + * "afs@CAMBRIDGE.REDHAT.COM> + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "ar-internal.h" + +static int rxrpc_vet_description_s(const char *); +static int rxrpc_preparse_s(struct key_preparsed_payload *); +static void rxrpc_free_preparse_s(struct key_preparsed_payload *); +static void rxrpc_destroy_s(struct key *); +static void rxrpc_describe_s(const struct key *, struct seq_file *); + +/* + * rxrpc server keys take ":[:]" as the + * description and the key material as the payload. + */ +struct key_type key_type_rxrpc_s = { + .name = "rxrpc_s", + .flags = KEY_TYPE_NET_DOMAIN, + .vet_description = rxrpc_vet_description_s, + .preparse = rxrpc_preparse_s, + .free_preparse = rxrpc_free_preparse_s, + .instantiate = generic_key_instantiate, + .destroy = rxrpc_destroy_s, + .describe = rxrpc_describe_s, +}; + +/* + * Vet the description for an RxRPC server key. + */ +static int rxrpc_vet_description_s(const char *desc) +{ + unsigned long service, sec_class; + char *p; + + service = simple_strtoul(desc, &p, 10); + if (*p != ':' || service > 65535) + return -EINVAL; + sec_class = simple_strtoul(p + 1, &p, 10); + if ((*p && *p != ':') || sec_class < 1 || sec_class > 255) + return -EINVAL; + return 0; +} + +/* + * Preparse a server secret key. + */ +static int rxrpc_preparse_s(struct key_preparsed_payload *prep) +{ + const struct rxrpc_security *sec; + unsigned int service, sec_class; + int n; + + _enter("%zu", prep->datalen); + + if (!prep->orig_description) + return -EINVAL; + + if (sscanf(prep->orig_description, "%u:%u%n", &service, &sec_class, &n) != 2) + return -EINVAL; + + sec = rxrpc_security_lookup(sec_class); + if (!sec) + return -ENOPKG; + + prep->payload.data[1] = (struct rxrpc_security *)sec; + + if (!sec->preparse_server_key) + return -EINVAL; + + return sec->preparse_server_key(prep); +} + +static void rxrpc_free_preparse_s(struct key_preparsed_payload *prep) +{ + const struct rxrpc_security *sec = prep->payload.data[1]; + + if (sec && sec->free_preparse_server_key) + sec->free_preparse_server_key(prep); +} + +static void rxrpc_destroy_s(struct key *key) +{ + const struct rxrpc_security *sec = key->payload.data[1]; + + if (sec && sec->destroy_server_key) + sec->destroy_server_key(key); +} + +static void rxrpc_describe_s(const struct key *key, struct seq_file *m) +{ + const struct rxrpc_security *sec = key->payload.data[1]; + + seq_puts(m, key->description); + if (sec && sec->describe_server_key) + sec->describe_server_key(key, m); +} + +/* + * grab the security keyring for a server socket + */ +int rxrpc_server_keyring(struct rxrpc_sock *rx, sockptr_t optval, int optlen) +{ + struct key *key; + char *description; + + _enter(""); + + if (rx->securities) + return -EINVAL; + + if (optlen <= 0 || optlen > PAGE_SIZE - 1) + return -EINVAL; + + description = memdup_sockptr_nul(optval, optlen); + if (IS_ERR(description)) + return PTR_ERR(description); + + key = request_key(&key_type_keyring, description, NULL); + if (IS_ERR(key)) { + kfree(description); + _leave(" = %ld", PTR_ERR(key)); + return PTR_ERR(key); + } + + rx->securities = key; + kfree(description); + _leave(" = 0 [key %x]", key->serial); + return 0; +} + +/** + * rxrpc_sock_set_security_keyring - Set the security keyring for a kernel service + * @sk: The socket to set the keyring on + * @keyring: The keyring to set + * + * Set the server security keyring on an rxrpc socket. This is used to provide + * the encryption keys for a kernel service. + * + * Return: %0 if successful and a negative error code otherwise. + */ +int rxrpc_sock_set_security_keyring(struct sock *sk, struct key *keyring) +{ + struct rxrpc_sock *rx = rxrpc_sk(sk); + int ret = 0; + + lock_sock(sk); + if (rx->securities) + ret = -EINVAL; + else if (rx->sk.sk_state != RXRPC_UNBOUND) + ret = -EISCONN; + else + rx->securities = key_get(keyring); + release_sock(sk); + return ret; +} +EXPORT_SYMBOL(rxrpc_sock_set_security_keyring); + +/** + * rxrpc_sock_set_manage_response - Set the manage-response flag for a kernel service + * @sk: The socket to set the keyring on + * @set: True to set, false to clear the flag + * + * Set the flag on an rxrpc socket to say that the caller wants to manage the + * RESPONSE packet and the user-defined data it may contain. Setting this + * means that recvmsg() will return messages with RXRPC_CHALLENGED in the + * control message buffer containing information about the challenge. + * + * The user should respond to the challenge by passing RXRPC_RESPOND or + * RXRPC_RESPOND_ABORT control messages with sendmsg() to the same call. + * Supplementary control messages, such as RXRPC_RESP_RXGK_APPDATA, may be + * included to indicate the parts the user wants to supply. + * + * The server will be passed the response data with a RXRPC_RESPONDED control + * message when it gets the first data from each call. + * + * Note that this is only honoured by security classes that need auxiliary data + * (e.g. RxGK). Those that don't offer the facility (e.g. RxKAD) respond + * without consulting userspace. + * + * Return: The previous setting. + */ +int rxrpc_sock_set_manage_response(struct sock *sk, bool set) +{ + struct rxrpc_sock *rx = rxrpc_sk(sk); + int ret; + + lock_sock(sk); + ret = !!test_bit(RXRPC_SOCK_MANAGE_RESPONSE, &rx->flags); + if (set) + set_bit(RXRPC_SOCK_MANAGE_RESPONSE, &rx->flags); + else + clear_bit(RXRPC_SOCK_MANAGE_RESPONSE, &rx->flags); + release_sock(sk); + return ret; +} +EXPORT_SYMBOL(rxrpc_sock_set_manage_response); -- cgit v1.3.1