Locks in forensics from boot -9..-1 journal:
- Silent watchdog reset, no oops/panic in logs
- vblank/edp WARNs are pre-existing (also fire on recovered boot 0)
- vb2_buffer_attach_release_fence / dma_fence / dma_resv NEVER
appear in iter6-boot kernel logs — deadlock at a level kernel
can't reach printk
- Hardware Synopsys DesignWare watchdog is the reset mechanism
Six non-negotiable safeguards for any retry:
1. backup .ko AND off-device archive before sudo install
2. CONFIG_PROVE_LOCKING + DEBUG_ATOMIC_SLEEP + LOCKDEP etc
3. bisect-apply one patch at a time, reboot+test between
4. SDDM auto-login OFF (done — file renamed .disabled-iter6postmortem)
5. pstore.backend=ramoops to capture kernel oops across reset
6. Phase 5 architect review of plan + 0007 source before apply
Four gating questions for Phase 1, starting with bisect:
- which of 4 patches is the actual vector
- lockdep splat hidden by CONFIG_PROVE_LOCKING=n
- why no oops in journal
- producer-side fence-alloc hang vs consumer-side wait hang
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Markus Fritsche