run.log — DF-5793 baseline, directed rig, 10s, stock kernel, uid 1001

$ /home/maxx/dup_directed 10
spammer: attempts=117 slow=10 err=0 errno_last=9(Bad file descriptor)
directed: pipes=5129795

$ dmesg | grep -c "target descriptor"
10
$ dmesg | grep "target descriptor" | head -3
Warning: dup(): target descriptor 3 is reserved, waiting for it to be resolved
Warning: dup(): target descriptor 3 is reserved, waiting for it to be resolved
Warning: dup(): target descriptor 3 is reserved, waiting for it to be resolved

Interpretation: 10 of 117 dup2() attempts (8.5%) hit the pipe()'s in-flight
reservation of fd 3; each parked the thread for the full 1s uninterruptible
tsleep and printed one unrate-limited kernel message (steady state: 1
line + 1 parked second per hit, per thread, sustained forever).