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/mac80211/drop.h | 139 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 139 insertions(+) create mode 100644 net/mac80211/drop.h (limited to 'net/mac80211/drop.h') diff --git a/net/mac80211/drop.h b/net/mac80211/drop.h new file mode 100644 index 000000000..f06a8aa90 --- /dev/null +++ b/net/mac80211/drop.h @@ -0,0 +1,139 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * mac80211 drop reason list + * + * Copyright (C) 2023-2024, 2026 Intel Corporation + */ + +#ifndef MAC80211_DROP_H +#define MAC80211_DROP_H +#include + +typedef unsigned int __bitwise ieee80211_rx_result; + +#define MAC80211_DROP_REASONS_UNUSABLE(R) \ + /* 0x00 == ___RX_DROP_UNUSABLE */ \ + R(RX_DROP_U_MIC_FAIL) \ + R(RX_DROP_U_REPLAY) \ + R(RX_DROP_U_BAD_MMIE) \ + R(RX_DROP_U_DUP) \ + R(RX_DROP_U_SPURIOUS) \ + R(RX_DROP_U_DECRYPT_FAIL) \ + R(RX_DROP_U_NO_KEY_ID) \ + R(RX_DROP_U_BAD_CIPHER) \ + R(RX_DROP_U_OOM) \ + R(RX_DROP_U_NONSEQ_PN) \ + R(RX_DROP_U_BAD_KEY_COLOR) \ + R(RX_DROP_U_BAD_4ADDR) \ + R(RX_DROP_U_BAD_AMSDU) \ + R(RX_DROP_U_BAD_AMSDU_CIPHER) \ + R(RX_DROP_U_INVALID_8023) \ + /* 0x10 */ \ + R(RX_DROP_U_RUNT_ACTION) \ + R(RX_DROP_U_UNPROT_ACTION) \ + R(RX_DROP_U_UNPROT_DUAL) \ + R(RX_DROP_U_UNPROT_UCAST_MGMT) \ + R(RX_DROP_U_UNPROT_MCAST_MGMT) \ + R(RX_DROP_U_UNPROT_BEACON) \ + R(RX_DROP_U_UNPROT_UNICAST_PUB_ACTION) \ + R(RX_DROP_U_UNPROT_ROBUST_ACTION) \ + R(RX_DROP_U_ACTION_UNKNOWN_SRC) \ + R(RX_DROP_U_REJECTED_ACTION_RESPONSE) \ + R(RX_DROP_U_EXPECT_DEFRAG_PROT) \ + R(RX_DROP_U_WEP_DEC_FAIL) \ + R(RX_DROP_U_NO_IV) \ + R(RX_DROP_U_NO_ICV) \ + R(RX_DROP_U_AP_RX_GROUPCAST) \ + R(RX_DROP_U_SHORT_MMIC) \ + /* 0x20 */ \ + R(RX_DROP_U_MMIC_FAIL) \ + R(RX_DROP_U_SHORT_TKIP) \ + R(RX_DROP_U_TKIP_FAIL) \ + R(RX_DROP_U_SHORT_CCMP) \ + R(RX_DROP_U_SHORT_CCMP_MIC) \ + R(RX_DROP_U_SHORT_GCMP) \ + R(RX_DROP_U_SHORT_GCMP_MIC) \ + R(RX_DROP_U_SHORT_CMAC) \ + R(RX_DROP_U_SHORT_CMAC256) \ + R(RX_DROP_U_SHORT_GMAC) \ + R(RX_DROP_U_UNEXPECTED_VLAN_4ADDR) \ + R(RX_DROP_U_UNEXPECTED_STA_4ADDR) \ + R(RX_DROP_U_UNEXPECTED_VLAN_MCAST) \ + R(RX_DROP_U_NOT_PORT_CONTROL) \ + R(RX_DROP_U_UNEXPECTED_4ADDR_FRAME) \ + R(RX_DROP_U_BAD_BCN_KEYIDX) \ + /* 0x30 */ \ + R(RX_DROP_U_BAD_MGMT_KEYIDX) \ + R(RX_DROP_U_UNKNOWN_ACTION_REJECTED) \ + R(RX_DROP_U_MESH_DS_BITS) \ + R(RX_DROP_U_MESH_A3_MISMATCH) \ + R(RX_DROP_U_MESH_NO_A4) \ + R(RX_DROP_U_MESH_A4_MISMATCH) \ + R(RX_DROP_U_MESH_UNEXP_DATA) \ + R(RX_DROP_U_MESH_WRONG_ACTION) \ + R(RX_DROP_U_MESH_UNEXP_MGMT) \ + R(RX_DROP_U_SPURIOUS_NOTIF) \ + R(RX_DROP_U_RUNT_DATA) \ + R(RX_DROP_U_KEY_TAINTED) \ + R(RX_DROP_U_UNPROTECTED) \ + R(RX_DROP_U_MCAST_FRAGMENT) \ + R(RX_DROP_U_DEFRAG_MISMATCH) \ + R(RX_DROP_U_RUNT_MESH_DATA) \ + /* 0x40 */ \ + R(RX_DROP_U_MESH_NO_TTL) \ + R(RX_DROP_U_MESH_RMC) \ + R(RX_DROP_U_MESH_BAD_AE) \ + R(RX_DROP_U_MESH_TTL_EXPIRED) \ + R(RX_DROP_U_MESH_NOT_FORWARDING) \ + R(RX_DROP_U_AMSDU_WITHOUT_DATA) \ + R(RX_DROP_U_NULL_DATA) \ + R(RX_DROP_U_UNEXPECTED_4ADDR) \ + R(RX_DROP_U_PORT_CONTROL) \ + R(RX_DROP_U_UNKNOWN_STA) \ + R(RX_DROP_U_RUNT_BAR) \ + R(RX_DROP_U_BAR_OUTSIDE_SESSION) \ + R(RX_DROP_U_CTRL_FRAME) \ + R(RX_DROP_U_RUNT_MGMT) \ + R(RX_DROP_U_EXPECTED_MGMT) \ + R(RX_DROP_U_NONBCAST_BEACON) \ + /* 0x50 */ \ + R(RX_DROP_U_MALFORMED_ACTION) \ + R(RX_DROP_U_UNKNOWN_MCAST_ACTION) \ + R(RX_DROP_U_UNEXPECTED_EXT_FRAME) \ + R(RX_DROP_U_UNHANDLED_MGMT) \ + R(RX_DROP_U_MCAST_DEAUTH) \ + R(RX_DROP_U_UNHANDLED_DEAUTH) \ + R(RX_DROP_U_MCAST_DISASSOC) \ + R(RX_DROP_U_UNHANDLED_DISASSOC) \ + R(RX_DROP_U_UNHANDLED_PREQ) \ + R(RX_DROP_U_UNHANDLED_MGMT_STYPE) \ + R(RX_DROP_U_NO_LINK) \ +/* this line for the trailing \ - add before this */ + +/* having two enums allows for checking ieee80211_rx_result use with sparse */ +enum ___mac80211_drop_reason { +/* if we get to the end of handlers with RX_CONTINUE this will be the reason */ + ___RX_CONTINUE = SKB_CONSUMED, + +/* this never gets used as an argument to kfree_skb_reason() */ + ___RX_QUEUED = SKB_NOT_DROPPED_YET, + +#define ENUM(x) ___ ## x, + ___RX_DROP_UNUSABLE = SKB_DROP_REASON_SUBSYS_MAC80211_UNUSABLE << + SKB_DROP_REASON_SUBSYS_SHIFT, + MAC80211_DROP_REASONS_UNUSABLE(ENUM) +#undef ENUM +}; + +enum mac80211_drop_reason { + RX_CONTINUE = (__force ieee80211_rx_result)___RX_CONTINUE, + RX_QUEUED = (__force ieee80211_rx_result)___RX_QUEUED, +#define DEF(x) x = (__force ieee80211_rx_result)___ ## x, + MAC80211_DROP_REASONS_UNUSABLE(DEF) +#undef DEF +}; + +#define RX_RES_IS_UNUSABLE(result) \ + (((__force u32)(result) & SKB_DROP_REASON_SUBSYS_MASK) == ___RX_DROP_UNUSABLE) + +#endif /* MAC80211_DROP_H */ -- cgit v1.3.1