From 6e4d311545141122560aa361b4b6eec510afdafc Mon Sep 17 00:00:00 2001 From: Keith Jackson Date: Tue, 1 Sep 2026 23:04:56 -0500 Subject: [PATCH] =?UTF-8?q?docs(prod):=20will=206.12.y=20get=20the=20memat?= =?UTF-8?q?tr=20fix=3F=20Researched=20=E2=80=94=20not=20on=20its=20own?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Operator asked whether waiting is viable or whether a backports kernel is permanent. Answer: it will NOT arrive on its own, but it CAN be made to, and the ask is unusually strong. VERIFIED: - NOT in linux-6.12.y. Newest commit touching memattr.c on that branch is 2024-07-12. In mainline since v6.13 (2025-01-19) — ~19 months, ~97 point releases. - NO stable tag and NO Fixes: tag on either commit. Structural, not an oversight: the unvalidated arithmetic dates to the file's creation in 2016, so it is not a regression and there is no bad commit to point Fixes: at. BOTH automatic feeds — Fixes:-scanning and AUTOSEL — had nothing to grab. AUTOSEL never surfaced it for any branch. - NOBODY has requested it: nothing on stable@vger.kernel.org, nothing in all 8,027 open+archived Debian bugs against src:linux. - 6.12 LTS EOL is December 2028 — outlives Debian 13's support window, so not time-barred. - Debian REBASES: trixie carries 6.12.94-1 in trixie-security ('New upstream stable update'), so an upstream pickup would reach us via a normal apt upgrade. THE DECISIVE CARD: the cherry-pick is BYTE-CLEAN. Debian trixie 6.12.94-1's memattr.c hashes to 164203429fa7a..., identical to the upstream patch's pre-image blob — the file has not diverged between v6.12 and the commit's parent. cherry-pick applies with zero conflicts and zero adjustment, which removes the usual reason such requests get declined. The commit also meets every stable-kernel-rules criterion: mainline, 17 insertions, 'hardware quirk', 'a real bug that bothers people'. PLAN: backports now as explicitly provisional; email stable@vger.kernel.org (rules Option 2) CC linux-efi and Ard Biesheuvel who authored AND committed it as EFI maintainer, leading with the clean-apply proof and the three-boot reproduction with byte-identical e820; Debian BTS as secondary under handbook §9.1.7; make the deviation permanent only if there is no movement in 4-6 weeks. Only 8fbe4c49c0cc is needed by hand — 5d0faa8e8369 loosens a heuristic that was rejecting LEGITIMATE tables and is not required for this symptom. Serves: R-ENV-01, R-ENV-03. Task: T-7.1. --- infra/PROD-PROVISIONING.md | 55 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) diff --git a/infra/PROD-PROVISIONING.md b/infra/PROD-PROVISIONING.md index c19e035..684d605 100644 --- a/infra/PROD-PROVISIONING.md +++ b/infra/PROD-PROVISIONING.md @@ -157,6 +157,61 @@ Same signature reported elsewhere: [Ubuntu LP #2039382](https://bugs.launchpad.n table) and [LP #1944019](https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1944019) (**HP ZBook Studio G5**, 16 GiB → 1.5 GiB). +### Will 6.12 ever get the fix? — researched 2026-09-02. **Not on its own.** + +| Question | Answer | +|---|---| +| In `linux-6.12.y` today? | **No.** Newest commit touching `memattr.c` on that branch is 2024-07-12. | +| How long has it been available? | In mainline since **v6.13, 2025-01-19** — ~19 months and ~97 6.12.y point releases. | +| Tagged `Cc: stable`? | **No.** Neither commit. | +| Tagged `Fixes:`? | **No** — and this is structural, not an oversight. The unvalidated arithmetic has been there since the file was created in **2016**; it is not a regression, so there is no bad commit to point a `Fixes:` at. **Both automatic feeds — the `Fixes:`-scanning scripts and AUTOSEL — had nothing to grab.** | +| Picked up by AUTOSEL? | **Never surfaced** for any branch. | +| Has anyone asked? | **No.** Nothing on `stable@vger.kernel.org`, and nothing in all 8,027 open+archived Debian bugs against `src:linux`. We would be first. | +| 6.12 LTS horizon | **EOL December 2028** — outlives Debian 13's own support window, so a backport is *not* time-barred. | + +**Every automatic path has already had its chance and produced nothing.** The probability that 6.12.y +acquires this commit spontaneously is close to zero. + +**But the request is unusually strong, and the cost is one email.** The decisive card: the cherry-pick +is **byte-clean**. Debian trixie 6.12.94-1's `drivers/firmware/efi/memattr.c` hashes to +`164203429fa7a…`, **identical to the upstream patch's pre-image blob** — the file has not diverged at +all between v6.12 and the commit's parent, so `git cherry-pick 8fbe4c49c0cc` applies with zero +conflicts and zero adjustment. Neither the stable team nor Debian would have any backporting work to +do, which removes the usual reason such requests are declined. The commit also meets every criterion +in `stable-kernel-rules.rst`: in mainline, 17 insertions (limit 100 lines), fixes "a hardware quirk" +and "a real bug that bothers people" — the enumerated categories. + +**Debian rebases**, so an upstream pickup reaches us automatically: trixie carries `linux 6.12.94-1` +in *trixie-security* whose changelog opens *"New upstream stable update: ChangeLog-6.12.91"*. No +action beyond `apt upgrade`. + +#### Plan + +1. **Run `trixie-backports` on both prod nodes now**, as an explicitly *provisional* measure. Any + 6.13+ kernel carries the fix. Record the standing cost: backports packages are provided as-is, + without the main archive's security guarantees. +2. **Email `stable@vger.kernel.org`** — this is `stable-kernel-rules.rst` Option 2 for an + already-merged patch. CC `linux-efi@vger.kernel.org` and **Ard Biesheuvel ``**, + who both authored and committed the fix as EFI maintainer. Include: the commit ID and subject; + **6.12.y only**; the byte-clean-apply proof above (it pre-empts the main objection); and the + reproduction — three consecutive boots on one machine, two outcomes, **byte-identical + `BIOS-e820` across all three** (the detail that proves the divergence is in the MAT, not the + memory map), 16 GB → 2.6 GiB, plus a second identical machine taking the safe path only by + chance. Attach both dmesgs. Corroboration exists: + [Ubuntu LP #1944019](https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1944019) (HP ZBook G5, + 16 GiB → 1.5 GiB) and SUSE bugzilla 1231465, cited in the commit message itself. +3. **File a Debian BTS bug as secondary**, against `src:linux` via `reportbug` (the bug-script + metadata is mandatory), severity `important`, referencing the lore thread. Debian's kernel + handbook §9.1.7 allows cherry-picking a patch already accepted upstream — which this is, + maintainer-authored with two Acked-bys — so if stable@ goes quiet Debian can act on its own. +4. **Trigger to make the deviation permanent:** no stable@ pickup within ~2 release cycles (4–6 + weeks) and no Debian movement ⇒ encode the backports kernel in the provisioning IaC for every + prod node and document it as a standing deviation from the distro baseline. + +**If patching by hand, only `8fbe4c49c0cc` is needed.** The follow-up `5d0faa8e8369` loosens a +heuristic that was rejecting *legitimate* tables (false kexec warnings in Meta's fleet); it is not +required for this symptom and depends on the first commit anyway. + ### What NOT to do - **Do not buy RAM, move the DIMM, RMA the board, or run memtest expecting failures.** The DIMM is