vgsp: stale-wedge recovery round 2 - dead-range reset, no residual publish

r227 field result: the watchdog fired 10x (reason=stale-epoch, arm+publish)
but the wedge survived, and victory_mail after the stalled rerun also hung.
Root causes fixed here:

1. Do NOT arm/publish on a residual epoch. Arming let the next pass's
   svc_counter_publish write the residual put (35/101) into the fresh
   client's completion word - the r207/mm2 far-jump wedge
   (UVM_GPU_SEMAPHORE_MAX_JUMP), the exact poison gr_pub_armed exists to
   prevent. The epoch reset now only zeroes a word the HOST published
   this session (counter_last != 0, m181 semantics); the arm stays at
   m181's put-drop and the pristine put <= 1 discovery.

2. The stale-replay leg could never fire: its predicate required
   wd_since (set only when a candidate armed the window) - a circular
   dependency. The window now arms on either candidate and the action is
   decided at fire time with proof of the livelock (submissions moved
   during the stalled window).

3. Dead-range reset (reason=stale-dead-range): when the host caught up
   but the whole consumed range delivered nothing (counter_last == 0,
   submissions >= 8) and the epoch was never armed, rewind last_get to
   slot 0 so the fresh session's own entries (which start at slot 0) can
   be walked, and force replay for those dead slots (wd_nocap_put) so the
   re-walk decodes releases only (idempotent, forward-only) and never
   re-captures/re-forwards a dead launch. Once per put epoch
   (wd_epoch_done), cleared when new producer work arrives.

4. Log extended: reason=stale-epoch|stale-dead-range|stale-replay plus
   reset=/rewind=/cpa=/rpa= so the next run shows exactly which recovery
   ran and whether a publish target even exists.

Green safety: both epoch legs require !gr_pub_armed (a channel that never
proved a fresh epoch); a green mid-stream-discovered unarmed channel can
at worst pay one forced-replay re-read of its consumed range per put epoch
(no capture, no word writes). The r220 hold-storm guard and the rewind
cooldown are untouched. make kernel green.

(cherry picked from commit d2ba3cadecf1ca0e72358024f80dbe7a8c468842)

0 files changed, 0 insertions, 0 deletions