1 .. _stable_kernel_rules:
3 Everything you ever wanted to know about Linux -stable releases
4 ===============================================================
6 Rules on what kind of patches are accepted, and which ones are not, into the
9 - It or an equivalent fix must already exist in Linus' tree (upstream).
10 - It must be obviously correct and tested.
11 - It cannot be bigger than 100 lines, with context.
13 :ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
15 - It must either fix a real bug that bothers people or just add a device ID.
16 To elaborate on the former:
18 - It fixes a problem like an oops, a hang, data corruption, a real security
19 issue, a hardware quirk, a build error (but not for things marked
20 CONFIG_BROKEN), or some "oh, that's not good" issue.
21 - Serious issues as reported by a user of a distribution kernel may also
22 be considered if they fix a notable performance or interactivity issue.
23 As these fixes are not as obvious and have a higher risk of a subtle
24 regression they should only be submitted by a distribution kernel
25 maintainer and include an addendum linking to a bugzilla entry if it
26 exists and additional information on the user-visible impact.
27 - No "This could be a problem..." type of things like a "theoretical race
28 condition", unless an explanation of how the bug can be exploited is also
30 - No "trivial" fixes without benefit for users (spelling changes, whitespace
34 Procedure for submitting patches to the -stable tree
35 ----------------------------------------------------
39 Security patches should not be handled (solely) by the -stable review
40 process but should follow the procedures in
41 :ref:`Documentation/process/security-bugs.rst <securitybugs>`.
43 There are three options to submit a change to -stable trees:
45 1. Add a 'stable tag' to the description of a patch you then submit for
47 2. Ask the stable team to pick up a patch already mainlined.
48 3. Submit a patch to the stable team that is equivalent to a change already
51 The sections below describe each of the options in more detail.
53 :ref:`option_1` is **strongly** preferred, it is the easiest and most common.
54 :ref:`option_2` is mainly meant for changes where backporting was not considered
55 at the time of submission. :ref:`option_3` is an alternative to the two earlier
56 options for cases where a mainlined patch needs adjustments to apply in older
57 series (for example due to API changes).
59 When using option 2 or 3 you can ask for your change to be included in specific
60 stable series. When doing so, ensure the fix or an equivalent is applicable,
61 submitted, or already present in all newer stable trees still supported. This is
62 meant to prevent regressions that users might later encounter on updating, if
63 e.g. a fix merged for 5.19-rc1 would be backported to 5.10.y, but not to 5.15.y.
70 To have a patch you submit for mainline inclusion later automatically picked up
71 for stable trees, add the tag
75 Cc: stable@vger.kernel.org
77 in the sign-off area. Once the patch is mainlined it will be applied to the
78 stable tree without anything else needing to be done by the author or
81 To sent additional instructions to the stable team, use a shell-style inline
84 * To specify any additional patch prerequisites for cherry picking use the
85 following format in the sign-off area:
89 Cc: <stable@vger.kernel.org> # 3.3.x: a1f84a3: sched: Check for idle
90 Cc: <stable@vger.kernel.org> # 3.3.x: 1b9508f: sched: Rate-limit newidle
91 Cc: <stable@vger.kernel.org> # 3.3.x: fd21073: sched: Fix affinity logic
92 Cc: <stable@vger.kernel.org> # 3.3.x
93 Signed-off-by: Ingo Molnar <mingo@elte.hu>
95 The tag sequence has the meaning of:
99 git cherry-pick a1f84a3
100 git cherry-pick 1b9508f
101 git cherry-pick fd21073
102 git cherry-pick <this commit>
104 Note that for a patch series, you do not have to list as prerequisites the
105 patches present in the series itself. For example, if you have the following
113 where patch2 depends on patch1, you do not have to list patch1 as
114 prerequisite of patch2 if you have already marked patch1 for stable
117 * For patches that may have kernel version prerequisites specify them using
118 the following format in the sign-off area:
122 Cc: <stable@vger.kernel.org> # 3.3.x
124 The tag has the meaning of:
128 git cherry-pick <this commit>
130 For each "-stable" tree starting with the specified version.
132 Note, such tagging is unnecessary if the stable team can derive the
133 appropriate versions from Fixes: tags.
135 * To delay pick up of patches, use the following format:
139 Cc: <stable@vger.kernel.org> # after 4 weeks in mainline
141 * For any other requests, just add a note to the stable tag. This for example
142 can be used to point out known problems:
146 Cc: <stable@vger.kernel.org> # see patch description, needs adjustments for <= 6.3
153 If the patch already has been merged to mainline, send an email to
154 stable@vger.kernel.org containing the subject of the patch, the commit ID,
155 why you think it should be applied, and what kernel versions you wish it to
163 Send the patch, after verifying that it follows the above rules, to
164 stable@vger.kernel.org and mention the kernel versions you wish it to be applied
165 to. When doing so, you must note the upstream commit ID in the changelog of your
166 submission with a separate line above the commit text, like this:
170 commit <sha1> upstream.
176 [ Upstream commit <sha1> ]
178 If the submitted patch deviates from the original upstream patch (for example
179 because it had to be adjusted for the older API), this must be very clearly
180 documented and justified in the patch description.
183 Following the submission
184 ------------------------
186 The sender will receive an ACK when the patch has been accepted into the
187 queue, or a NAK if the patch is rejected. This response might take a few
188 days, according to the schedules of the stable team members.
190 If accepted, the patch will be added to the -stable queue, for review by other
191 developers and by the relevant subsystem maintainer.
197 - When the -stable maintainers decide for a review cycle, the patches will be
198 sent to the review committee, and the maintainer of the affected area of
199 the patch (unless the submitter is the maintainer of the area) and CC: to
200 the linux-kernel mailing list.
201 - The review committee has 48 hours in which to ACK or NAK the patch.
202 - If the patch is rejected by a member of the committee, or linux-kernel
203 members object to the patch, bringing up issues that the maintainers and
204 members did not realize, the patch will be dropped from the queue.
205 - The ACKed patches will be posted again as part of release candidate (-rc)
206 to be tested by developers and testers.
207 - Usually only one -rc release is made, however if there are any outstanding
208 issues, some patches may be modified or dropped or additional patches may
209 be queued. Additional -rc releases are then released and tested until no
211 - Responding to the -rc releases can be done on the mailing list by sending
212 a "Tested-by:" email with any testing information desired. The "Tested-by:"
213 tags will be collected and added to the release commit.
214 - At the end of the review cycle, the new -stable release will be released
215 containing all the queued and tested patches.
216 - Security patches will be accepted into the -stable tree directly from the
217 security kernel team, and not go through the normal review cycle.
218 Contact the kernel security team for more details on this procedure.
224 - The queues of patches, for both completed versions and in progress
225 versions can be found at:
227 https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git
229 - The finalized and tagged releases of all stable kernels can be found
230 in separate branches per version at:
232 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
234 - The release candidate of all stable kernel versions can be found at:
236 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/
239 The -stable-rc tree is a snapshot in time of the stable-queue tree and
240 will change frequently, hence will be rebased often. It should only be
241 used for testing purposes (e.g. to be consumed by CI systems).
247 - This is made up of a number of kernel developers who have volunteered for
248 this task, and a few that haven't.