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/sunrpc/svcauth.c | 303 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 303 insertions(+) create mode 100644 net/sunrpc/svcauth.c (limited to 'net/sunrpc/svcauth.c') diff --git a/net/sunrpc/svcauth.c b/net/sunrpc/svcauth.c new file mode 100644 index 000000000..55b4d2874 --- /dev/null +++ b/net/sunrpc/svcauth.c @@ -0,0 +1,303 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/net/sunrpc/svcauth.c + * + * The generic interface for RPC authentication on the server side. + * + * Copyright (C) 1995, 1996 Olaf Kirch + * + * CHANGES + * 19-Apr-2000 Chris Evans - Security fix + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "sunrpc.h" + +#define RPCDBG_FACILITY RPCDBG_AUTH + + +/* + * Table of authenticators + */ +extern struct auth_ops svcauth_null; +extern struct auth_ops svcauth_unix; +extern struct auth_ops svcauth_tls; + +static struct auth_ops __rcu *authtab[RPC_AUTH_MAXFLAVOR] = { + [RPC_AUTH_NULL] = (struct auth_ops __force __rcu *)&svcauth_null, + [RPC_AUTH_UNIX] = (struct auth_ops __force __rcu *)&svcauth_unix, + [RPC_AUTH_TLS] = (struct auth_ops __force __rcu *)&svcauth_tls, +}; + +static struct auth_ops * +svc_get_auth_ops(rpc_authflavor_t flavor) +{ + struct auth_ops *aops; + + if (flavor >= RPC_AUTH_MAXFLAVOR) + return NULL; + rcu_read_lock(); + aops = rcu_dereference(authtab[flavor]); + if (aops != NULL && !try_module_get(aops->owner)) + aops = NULL; + rcu_read_unlock(); + return aops; +} + +static void +svc_put_auth_ops(struct auth_ops *aops) +{ + module_put(aops->owner); +} + +/** + * svc_authenticate - Initialize an outgoing credential + * @rqstp: RPC execution context + * + * Return values: + * %SVC_OK: XDR encoding of the result can begin + * %SVC_DENIED: Credential or verifier is not valid + * %SVC_GARBAGE: Failed to decode credential or verifier + * %SVC_COMPLETE: GSS context lifetime event; no further action + * %SVC_DROP: Drop this request; no further action + * %SVC_CLOSE: Like drop, but also close transport connection + */ +enum svc_auth_status svc_authenticate(struct svc_rqst *rqstp) +{ + struct auth_ops *aops; + u32 flavor; + + rqstp->rq_auth_stat = rpc_auth_ok; + + /* + * Decode the Call credential's flavor field. The credential's + * body field is decoded in the chosen ->accept method below. + */ + if (xdr_stream_decode_u32(&rqstp->rq_arg_stream, &flavor) < 0) + return SVC_GARBAGE; + + aops = svc_get_auth_ops(flavor); + if (aops == NULL) { + rqstp->rq_auth_stat = rpc_autherr_badcred; + return SVC_DENIED; + } + + rqstp->rq_auth_slack = 0; + init_svc_cred(&rqstp->rq_cred); + + rqstp->rq_authop = aops; + return aops->accept(rqstp); +} + +/** + * svc_set_client - Assign an appropriate 'auth_domain' as the client + * @rqstp: RPC execution context + * + * Return values: + * %SVC_OK: Client was found and assigned + * %SVC_DENY: Client was explicitly denied + * %SVC_DROP: Ignore this request + * %SVC_CLOSE: Ignore this request and close the connection + */ +enum svc_auth_status svc_set_client(struct svc_rqst *rqstp) +{ + rqstp->rq_client = NULL; + return rqstp->rq_authop->set_client(rqstp); +} +EXPORT_SYMBOL_GPL(svc_set_client); + +/** + * svc_authorise - Finalize credentials/verifier and release resources + * @rqstp: RPC execution context + * + * Returns zero on success, or a negative errno. + */ +int svc_authorise(struct svc_rqst *rqstp) +{ + struct auth_ops *aops = rqstp->rq_authop; + int rv = 0; + + rqstp->rq_authop = NULL; + + if (aops) { + rv = aops->release(rqstp); + svc_put_auth_ops(aops); + } + return rv; +} + +int +svc_auth_register(rpc_authflavor_t flavor, struct auth_ops *aops) +{ + struct auth_ops *old; + int rv = -EINVAL; + + if (flavor < RPC_AUTH_MAXFLAVOR) { + old = cmpxchg((struct auth_ops ** __force)&authtab[flavor], NULL, aops); + if (old == NULL || old == aops) + rv = 0; + } + return rv; +} +EXPORT_SYMBOL_GPL(svc_auth_register); + +void +svc_auth_unregister(rpc_authflavor_t flavor) +{ + if (flavor < RPC_AUTH_MAXFLAVOR) + rcu_assign_pointer(authtab[flavor], NULL); +} +EXPORT_SYMBOL_GPL(svc_auth_unregister); + +/** + * svc_auth_flavor - return RPC transaction's RPC_AUTH flavor + * @rqstp: RPC transaction context + * + * Returns an RPC flavor or GSS pseudoflavor. + */ +rpc_authflavor_t svc_auth_flavor(struct svc_rqst *rqstp) +{ + struct auth_ops *aops = rqstp->rq_authop; + + if (!aops->pseudoflavor) + return aops->flavour; + return aops->pseudoflavor(rqstp); +} +EXPORT_SYMBOL_GPL(svc_auth_flavor); + +/** + * svcauth_map_clnt_to_svc_cred_local - maps a generic cred + * to a svc_cred suitable for use in nfsd. + * @clnt: rpc_clnt associated with nfs client + * @cred: generic cred associated with nfs client + * @svc: returned svc_cred that is suitable for use in nfsd + */ +void svcauth_map_clnt_to_svc_cred_local(struct rpc_clnt *clnt, + const struct cred *cred, + struct svc_cred *svc) +{ + struct user_namespace *userns = clnt->cl_cred ? + clnt->cl_cred->user_ns : &init_user_ns; + + memset(svc, 0, sizeof(struct svc_cred)); + + svc->cr_uid = KUIDT_INIT(from_kuid_munged(userns, cred->fsuid)); + svc->cr_gid = KGIDT_INIT(from_kgid_munged(userns, cred->fsgid)); + svc->cr_flavor = clnt->cl_auth->au_flavor; + if (cred->group_info) + svc->cr_group_info = get_group_info(cred->group_info); + /* These aren't relevant for local (network is bypassed) */ + svc->cr_principal = NULL; + svc->cr_gss_mech = NULL; +} +EXPORT_SYMBOL_GPL(svcauth_map_clnt_to_svc_cred_local); + +/************************************************** + * 'auth_domains' are stored in a hash table indexed by name. + * When the last reference to an 'auth_domain' is dropped, + * the object is unhashed and freed. + * If auth_domain_lookup fails to find an entry, it will return + * it's second argument 'new'. If this is non-null, it will + * have been atomically linked into the table. + */ + +#define DN_HASHBITS 6 +#define DN_HASHMAX (1<hash); + dom->flavour->domain_release(dom); + spin_unlock(&auth_domain_lock); +} + +void auth_domain_put(struct auth_domain *dom) +{ + kref_put_lock(&dom->ref, auth_domain_release, &auth_domain_lock); +} +EXPORT_SYMBOL_GPL(auth_domain_put); + +struct auth_domain * +auth_domain_lookup(char *name, struct auth_domain *new) +{ + struct auth_domain *hp; + struct hlist_head *head; + + head = &auth_domain_table[hash_str(name, DN_HASHBITS)]; + + spin_lock(&auth_domain_lock); + + hlist_for_each_entry(hp, head, hash) { + if (strcmp(hp->name, name)==0) { + kref_get(&hp->ref); + spin_unlock(&auth_domain_lock); + return hp; + } + } + if (new) + hlist_add_head_rcu(&new->hash, head); + spin_unlock(&auth_domain_lock); + return new; +} +EXPORT_SYMBOL_GPL(auth_domain_lookup); + +struct auth_domain *auth_domain_find(char *name) +{ + struct auth_domain *hp; + struct hlist_head *head; + + head = &auth_domain_table[hash_str(name, DN_HASHBITS)]; + + rcu_read_lock(); + hlist_for_each_entry_rcu(hp, head, hash) { + if (strcmp(hp->name, name)==0) { + if (!kref_get_unless_zero(&hp->ref)) + hp = NULL; + rcu_read_unlock(); + return hp; + } + } + rcu_read_unlock(); + return NULL; +} +EXPORT_SYMBOL_GPL(auth_domain_find); + +/** + * auth_domain_cleanup - check that the auth_domain table is empty + * + * On module unload the auth_domain_table must be empty. To make it + * easier to catch bugs which don't clean up domains properly, we + * warn if anything remains in the table at cleanup time. + * + * Note that we cannot proactively remove the domains at this stage. + * The ->release() function might be in a module that has already been + * unloaded. + */ + +void auth_domain_cleanup(void) +{ + int h; + struct auth_domain *hp; + + for (h = 0; h < DN_HASHMAX; h++) + hlist_for_each_entry(hp, &auth_domain_table[h], hash) + pr_warn("svc: domain %s still present at module unload.\n", + hp->name); +} -- cgit v1.3.1