=== DF-2556 fix validation (diagnostic module, 20000 resize cycles) ===
[unpatched #0 kernel]:
  M_TTYS BEFORE: 37 allocs / 143K
  M_TTYS AFTER:  19.6K allocs / 332M   (leak: ~20000 buffers leaked)

[patched #1 kernel] (kfree old c_data added in clist_alloc_cblocks):
  M_TTYS BEFORE: 37 allocs / 143K
  M_TTYS AFTER:  37 allocs / 143K      (FLAT — leak closed)

kern.version patched: DragonFly 6.5-DEVELOPMENT #1: Sun Aug  9 05:09:04 UTC 2026
=> fix_status: fixed. Same module run; M_TTYS growth eliminated.