linux/linux-5.18.11/Documentation/process/stable-kernel-rules.rst

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.. _stable_kernel_rules:
Everything you ever wanted to know about Linux -stable releases
===============================================================
Rules on what kind of patches are accepted, and which ones are not, into the
"-stable" tree:
- It must be obviously correct and tested.
- It cannot be bigger than 100 lines, with context.
- It must fix only one thing.
- It must fix a real bug that bothers people (not a, "This could be a
problem..." type thing).
- It must fix a problem that causes a build error (but not for things
marked CONFIG_BROKEN), an oops, a hang, data corruption, a real
security issue, or some "oh, that's not good" issue. In short, something
critical.
- Serious issues as reported by a user of a distribution kernel may also
be considered if they fix a notable performance or interactivity issue.
As these fixes are not as obvious and have a higher risk of a subtle
regression they should only be submitted by a distribution kernel
maintainer and include an addendum linking to a bugzilla entry if it
exists and additional information on the user-visible impact.
- New device IDs and quirks are also accepted.
- No "theoretical race condition" issues, unless an explanation of how the
race can be exploited is also provided.
- It cannot contain any "trivial" fixes in it (spelling changes,
whitespace cleanups, etc).
- It must follow the
:ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
rules.
- It or an equivalent fix must already exist in Linus' tree (upstream).
Procedure for submitting patches to the -stable tree
----------------------------------------------------
.. note::
Security patches should not be handled (solely) by the -stable review
process but should follow the procedures in
:ref:`Documentation/admin-guide/security-bugs.rst <securitybugs>`.
For all other submissions, choose one of the following procedures
-----------------------------------------------------------------
.. _option_1:
Option 1
********
To have the patch automatically included in the stable tree, add the tag
.. code-block:: none
Cc: stable@vger.kernel.org
in the sign-off area. Once the patch is merged it will be applied to
the stable tree without anything else needing to be done by the author
or subsystem maintainer.
.. _option_2:
Option 2
********
After the patch has been merged to Linus' tree, send an email to
stable@vger.kernel.org containing the subject of the patch, the commit ID,
why you think it should be applied, and what kernel version you wish it to
be applied to.
.. _option_3:
Option 3
********
Send the patch, after verifying that it follows the above rules, to
stable@vger.kernel.org. You must note the upstream commit ID in the
changelog of your submission, as well as the kernel version you wish
it to be applied to.
:ref:`option_1` is **strongly** preferred, is the easiest and most common.
:ref:`option_2` and :ref:`option_3` are more useful if the patch isn't deemed
worthy at the time it is applied to a public git tree (for instance, because
it deserves more regression testing first). :ref:`option_3` is especially
useful if the original upstream patch needs to be backported (for example
the backport needs some special handling due to e.g. API changes).
Note that for :ref:`option_3`, if the patch deviates from the original
upstream patch (for example because it had to be backported) this must be very
clearly documented and justified in the patch description.
The upstream commit ID must be specified with a separate line above the commit
text, like this:
.. code-block:: none
commit <sha1> upstream.
Additionally, some patches submitted via :ref:`option_1` may have additional
patch prerequisites which can be cherry-picked. This can be specified in the
following format in the sign-off area:
.. code-block:: none
Cc: <stable@vger.kernel.org> # 3.3.x: a1f84a3: sched: Check for idle
Cc: <stable@vger.kernel.org> # 3.3.x: 1b9508f: sched: Rate-limit newidle
Cc: <stable@vger.kernel.org> # 3.3.x: fd21073: sched: Fix affinity logic
Cc: <stable@vger.kernel.org> # 3.3.x
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The tag sequence has the meaning of:
.. code-block:: none
git cherry-pick a1f84a3
git cherry-pick 1b9508f
git cherry-pick fd21073
git cherry-pick <this commit>
Also, some patches may have kernel version prerequisites. This can be
specified in the following format in the sign-off area:
.. code-block:: none
Cc: <stable@vger.kernel.org> # 3.3.x
The tag has the meaning of:
.. code-block:: none
git cherry-pick <this commit>
For each "-stable" tree starting with the specified version.
Following the submission:
- The sender will receive an ACK when the patch has been accepted into the
queue, or a NAK if the patch is rejected. This response might take a few
days, according to the developer's schedules.
- If accepted, the patch will be added to the -stable queue, for review by
other developers and by the relevant subsystem maintainer.
Review cycle
------------
- When the -stable maintainers decide for a review cycle, the patches will be
sent to the review committee, and the maintainer of the affected area of
the patch (unless the submitter is the maintainer of the area) and CC: to
the linux-kernel mailing list.
- The review committee has 48 hours in which to ACK or NAK the patch.
- If the patch is rejected by a member of the committee, or linux-kernel
members object to the patch, bringing up issues that the maintainers and
members did not realize, the patch will be dropped from the queue.
- The ACKed patches will be posted again as part of release candidate (-rc)
to be tested by developers and testers.
- Usually only one -rc release is made, however if there are any outstanding
issues, some patches may be modified or dropped or additional patches may
be queued. Additional -rc releases are then released and tested until no
issues are found.
- Responding to the -rc releases can be done on the mailing list by sending
a "Tested-by:" email with any testing information desired. The "Tested-by:"
tags will be collected and added to the release commit.
- At the end of the review cycle, the new -stable release will be released
containing all the queued and tested patches.
- Security patches will be accepted into the -stable tree directly from the
security kernel team, and not go through the normal review cycle.
Contact the kernel security team for more details on this procedure.
Trees
-----
- The queues of patches, for both completed versions and in progress
versions can be found at:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git
- The finalized and tagged releases of all stable kernels can be found
in separate branches per version at:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- The release candidate of all stable kernel versions can be found at:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/
.. warning::
The -stable-rc tree is a snapshot in time of the stable-queue tree and
will change frequently, hence will be rebased often. It should only be
used for testing purposes (e.g. to be consumed by CI systems).
Review committee
----------------
- This is made up of a number of kernel developers who have volunteered for
this task, and a few that haven't.