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/netlink.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100644 net/sunrpc/netlink.c (limited to 'net/sunrpc/netlink.c') diff --git a/net/sunrpc/netlink.c b/net/sunrpc/netlink.c new file mode 100644 index 000000000..ce09ecc0f --- /dev/null +++ b/net/sunrpc/netlink.c @@ -0,0 +1,97 @@ +// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) +/* Do not edit directly, auto-generated from: */ +/* Documentation/netlink/specs/sunrpc_cache.yaml */ +/* YNL-GEN kernel source */ +/* To regenerate run: tools/net/ynl/ynl-regen.sh */ + +#include +#include + +#include "netlink.h" + +#include + +/* Common nested types */ +const struct nla_policy sunrpc_ip_map_nl_policy[SUNRPC_A_IP_MAP_EXPIRY + 1] = { + [SUNRPC_A_IP_MAP_SEQNO] = { .type = NLA_U64, }, + [SUNRPC_A_IP_MAP_CLASS] = { .type = NLA_NUL_STRING, }, + [SUNRPC_A_IP_MAP_ADDR] = { .type = NLA_NUL_STRING, }, + [SUNRPC_A_IP_MAP_DOMAIN] = { .type = NLA_NUL_STRING, }, + [SUNRPC_A_IP_MAP_NEGATIVE] = { .type = NLA_FLAG, }, + [SUNRPC_A_IP_MAP_EXPIRY] = { .type = NLA_U64, }, +}; + +const struct nla_policy sunrpc_unix_gid_nl_policy[SUNRPC_A_UNIX_GID_EXPIRY + 1] = { + [SUNRPC_A_UNIX_GID_SEQNO] = { .type = NLA_U64, }, + [SUNRPC_A_UNIX_GID_UID] = { .type = NLA_U32, }, + [SUNRPC_A_UNIX_GID_GIDS] = { .type = NLA_U32, }, + [SUNRPC_A_UNIX_GID_NEGATIVE] = { .type = NLA_FLAG, }, + [SUNRPC_A_UNIX_GID_EXPIRY] = { .type = NLA_U64, }, +}; + +/* SUNRPC_CMD_IP_MAP_SET_REQS - do */ +static const struct nla_policy sunrpc_ip_map_set_reqs_nl_policy[SUNRPC_A_IP_MAP_REQS_REQUESTS + 1] = { + [SUNRPC_A_IP_MAP_REQS_REQUESTS] = NLA_POLICY_NESTED(sunrpc_ip_map_nl_policy), +}; + +/* SUNRPC_CMD_UNIX_GID_SET_REQS - do */ +static const struct nla_policy sunrpc_unix_gid_set_reqs_nl_policy[SUNRPC_A_UNIX_GID_REQS_REQUESTS + 1] = { + [SUNRPC_A_UNIX_GID_REQS_REQUESTS] = NLA_POLICY_NESTED(sunrpc_unix_gid_nl_policy), +}; + +/* SUNRPC_CMD_CACHE_FLUSH - do */ +static const struct nla_policy sunrpc_cache_flush_nl_policy[SUNRPC_A_CACHE_FLUSH_MASK + 1] = { + [SUNRPC_A_CACHE_FLUSH_MASK] = NLA_POLICY_MASK(NLA_U32, 0x3), +}; + +/* Ops table for sunrpc */ +static const struct genl_split_ops sunrpc_nl_ops[] = { + { + .cmd = SUNRPC_CMD_IP_MAP_GET_REQS, + .dumpit = sunrpc_nl_ip_map_get_reqs_dumpit, + .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP, + }, + { + .cmd = SUNRPC_CMD_IP_MAP_SET_REQS, + .doit = sunrpc_nl_ip_map_set_reqs_doit, + .policy = sunrpc_ip_map_set_reqs_nl_policy, + .maxattr = SUNRPC_A_IP_MAP_REQS_REQUESTS, + .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO, + }, + { + .cmd = SUNRPC_CMD_UNIX_GID_GET_REQS, + .dumpit = sunrpc_nl_unix_gid_get_reqs_dumpit, + .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP, + }, + { + .cmd = SUNRPC_CMD_UNIX_GID_SET_REQS, + .doit = sunrpc_nl_unix_gid_set_reqs_doit, + .policy = sunrpc_unix_gid_set_reqs_nl_policy, + .maxattr = SUNRPC_A_UNIX_GID_REQS_REQUESTS, + .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO, + }, + { + .cmd = SUNRPC_CMD_CACHE_FLUSH, + .doit = sunrpc_nl_cache_flush_doit, + .policy = sunrpc_cache_flush_nl_policy, + .maxattr = SUNRPC_A_CACHE_FLUSH_MASK, + .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO, + }, +}; + +static const struct genl_multicast_group sunrpc_nl_mcgrps[] = { + [SUNRPC_NLGRP_NONE] = { "none", }, + [SUNRPC_NLGRP_EXPORTD] = { "exportd", }, +}; + +struct genl_family sunrpc_nl_family __ro_after_init = { + .name = SUNRPC_FAMILY_NAME, + .version = SUNRPC_FAMILY_VERSION, + .netnsok = true, + .parallel_ops = true, + .module = THIS_MODULE, + .split_ops = sunrpc_nl_ops, + .n_split_ops = ARRAY_SIZE(sunrpc_nl_ops), + .mcgrps = sunrpc_nl_mcgrps, + .n_mcgrps = ARRAY_SIZE(sunrpc_nl_mcgrps), +}; -- cgit v1.3.1