Kernel fix-build log (essential lines; captured from the guest build session,
guest /tmp/build.log was lost in the mandated post-validation snapshot reset).

FIRST build (before removing the redundant MALLOC_DECLARE):
  /usr/src/sys/sys/proc.h:454:16: error: redundant redeclaration of 'M_PARGS' [-Werror=redundant-decls]
  /usr/src/sys/vfs/procfs/procfs_status.c:54:16: error: redundant redeclaration of 'M_PARGS' [-Werror=redundant-decls]
  cc1: all warnings being treated as errors
  *** Error code 1
  (fix: M_PARGS is already declared via sys/proc.h - dropped the local declare)

SECOND build (final fix.diff content):
  root@dfbsd: cd /usr/src && make nativekernel KERNCONF=X86_64_GENERIC
  BUILD_RC=0
  >>> Kernel build for X86_64_GENERIC completed on Wed Sep  9 02:48:03 UTC 2026
      1117.04 real      968.97 user      190.30 sys
  make installkernel: INSTK_RC=0
  >>> Kernel install for X86_64_GENERIC completed on Wed Sep  9 02:49:25 UTC 2026
  reboot -> DragonFly 6.5-DEVELOPMENT #1: Wed Sep  9 02:37:12 UTC 2026

NOTE: the shipped fix.diff is the clean regenerated diff WITHOUT the
redundant MALLOC_DECLARE (validated with `patch -p1 --dry-run` on a
pristine tree copy before shipping; the guest-side build used the same
content plus the two deleted declare lines).