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/ceph/ceph_strings.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 net/ceph/ceph_strings.c (limited to 'net/ceph/ceph_strings.c') diff --git a/net/ceph/ceph_strings.c b/net/ceph/ceph_strings.c new file mode 100644 index 000000000..355fea272 --- /dev/null +++ b/net/ceph/ceph_strings.c @@ -0,0 +1,90 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Ceph string constants + */ +#include +#include + +const char *ceph_entity_type_name(int type) +{ + switch (type) { + case CEPH_ENTITY_TYPE_MDS: return "mds"; + case CEPH_ENTITY_TYPE_OSD: return "osd"; + case CEPH_ENTITY_TYPE_MON: return "mon"; + case CEPH_ENTITY_TYPE_CLIENT: return "client"; + case CEPH_ENTITY_TYPE_AUTH: return "auth"; + default: return "unknown"; + } +} +EXPORT_SYMBOL(ceph_entity_type_name); + +const char *ceph_auth_proto_name(int proto) +{ + switch (proto) { + case CEPH_AUTH_UNKNOWN: + return "unknown"; + case CEPH_AUTH_NONE: + return "none"; + case CEPH_AUTH_CEPHX: + return "cephx"; + default: + return "???"; + } +} + +const char *ceph_con_mode_name(int mode) +{ + switch (mode) { + case CEPH_CON_MODE_UNKNOWN: + return "unknown"; + case CEPH_CON_MODE_CRC: + return "crc"; + case CEPH_CON_MODE_SECURE: + return "secure"; + default: + return "???"; + } +} + +const char *ceph_osd_op_name(int op) +{ + switch (op) { +#define GENERATE_CASE(op, opcode, str) case CEPH_OSD_OP_##op: return (str); +__CEPH_FORALL_OSD_OPS(GENERATE_CASE) +#undef GENERATE_CASE + default: + return "???"; + } +} + +const char *ceph_osd_watch_op_name(int o) +{ + switch (o) { + case CEPH_OSD_WATCH_OP_UNWATCH: + return "unwatch"; + case CEPH_OSD_WATCH_OP_WATCH: + return "watch"; + case CEPH_OSD_WATCH_OP_RECONNECT: + return "reconnect"; + case CEPH_OSD_WATCH_OP_PING: + return "ping"; + default: + return "???"; + } +} + +const char *ceph_osd_state_name(int s) +{ + switch (s) { + case CEPH_OSD_EXISTS: + return "exists"; + case CEPH_OSD_UP: + return "up"; + case CEPH_OSD_AUTOOUT: + return "autoout"; + case CEPH_OSD_NEW: + return "new"; + default: + return "???"; + } +} -- cgit v1.3.1