match_job_host_limit_() (plugins/limit.c) runs on every per-host
allocation attempt via limit_prepare_allocation(), and unconditionally
xlist_store()d the matched vres into obj->hlimits[worker->idx]. That list
is only rebuilt by limit_job_election() on a configver bump, so a job that
kept pending on the same host gained one more copy per attempt.
sched_fill_limit_requests() then staged every copy into
ctx->alloc_req.host, and seqjob's make_host_alloc() built a host alloc
carrying all of them.
Found via temporary per-decision --sim-verify diagnostics (reverted, not
committed) against scheduler-replay-20260923-085356.replay: pc13v host
allocs held mem + slots + ~70 identical limit entries (72) instead of 3.
After the fix the replay side is always 3 entries, and the LIVE recording
itself still shows the inflation (72/81/96/114/138/177 entries, resetting
only on a config push) -- so this is a production bug, not sim-only.
make_job_account() creates one res_account per entry and
sched_update_res_accounts() charges each, so the host limit was charged
(and later released) N-fold.
Fix: hlimits_contains_() pointer-identity check (vres is interned per name
in privdata->instances); a matched vres is stored once per (job, worker).
Test: test_limit_host_dedup.c (sched_limit_host_dedup_test) -- five
plugin_prepare_allocation() attempts for one job on one worker must leave
hlimits[worker]->count == 1 and one staged copy of the vres in
alloc_req.host. RED before the fix (Expected 1 Was 2), GREEN after; full
scheduler suite 86/86 (asan).
Still open (bug-1846 part 2, logged in buglog): 9 live-recorded rounds end
after 11-12 decisions while replay processes the whole candidate list; not
root-caused, needs the live scheduler.log or a fresh capture.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Rongsong Shen
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