1.. _stable_kernel_rules:
2
3Everything you ever wanted to know about Linux -stable releases
4===============================================================
5
6Rules on what kind of patches are accepted, and which ones are not, into the
7"-stable" tree:
8
9 - It must be obviously correct and tested.
10 - It cannot be bigger than 100 lines, with context.
11 - It must fix only one thing.
12 - It must fix a real bug that bothers people (not a, "This could be a
13   problem..." type thing).
14 - It must fix a problem that causes a build error (but not for things
15   marked CONFIG_BROKEN), an oops, a hang, data corruption, a real
16   security issue, or some "oh, that's not good" issue.  In short, something
17   critical.
18 - Serious issues as reported by a user of a distribution kernel may also
19   be considered if they fix a notable performance or interactivity issue.
20   As these fixes are not as obvious and have a higher risk of a subtle
21   regression they should only be submitted by a distribution kernel
22   maintainer and include an addendum linking to a bugzilla entry if it
23   exists and additional information on the user-visible impact.
24 - New device IDs and quirks are also accepted.
25 - No "theoretical race condition" issues, unless an explanation of how the
26   race can be exploited is also provided.
27 - It cannot contain any "trivial" fixes in it (spelling changes,
28   whitespace cleanups, etc).
29 - It must follow the
30   :ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
31   rules.
32 - It or an equivalent fix must already exist in Linus' tree (upstream).
33
34
35Procedure for submitting patches to the -stable tree
36----------------------------------------------------
37
38 - If the patch covers files in net/ or drivers/net please follow netdev stable
39   submission guidelines as described in
40   :ref:`Documentation/networking/netdev-FAQ.rst <netdev-FAQ>`
41 - Security patches should not be handled (solely) by the -stable review
42   process but should follow the procedures in
43   :ref:`Documentation/admin-guide/security-bugs.rst <securitybugs>`.
44
45For all other submissions, choose one of the following procedures
46-----------------------------------------------------------------
47
48.. _option_1:
49
50Option 1
51********
52
53To have the patch automatically included in the stable tree, add the tag
54
55.. code-block:: none
56
57     Cc: stable@vger.kernel.org
58
59in the sign-off area. Once the patch is merged it will be applied to
60the stable tree without anything else needing to be done by the author
61or subsystem maintainer.
62
63.. _option_2:
64
65Option 2
66********
67
68After the patch has been merged to Linus' tree, send an email to
69stable@vger.kernel.org containing the subject of the patch, the commit ID,
70why you think it should be applied, and what kernel version you wish it to
71be applied to.
72
73.. _option_3:
74
75Option 3
76********
77
78Send the patch, after verifying that it follows the above rules, to
79stable@vger.kernel.org.  You must note the upstream commit ID in the
80changelog of your submission, as well as the kernel version you wish
81it to be applied to.
82
83:ref:`option_1` is **strongly** preferred, is the easiest and most common.
84:ref:`option_2` and :ref:`option_3` are more useful if the patch isn't deemed
85worthy at the time it is applied to a public git tree (for instance, because
86it deserves more regression testing first).  :ref:`option_3` is especially
87useful if the patch needs some special handling to apply to an older kernel
88(e.g., if API's have changed in the meantime).
89
90Note that for :ref:`option_3`, if the patch deviates from the original
91upstream patch (for example because it had to be backported) this must be very
92clearly documented and justified in the patch description.
93
94The upstream commit ID must be specified with a separate line above the commit
95text, like this:
96
97.. code-block:: none
98
99    commit <sha1> upstream.
100
101Additionally, some patches submitted via Option 1 may have additional patch
102prerequisites which can be cherry-picked. This can be specified in the following
103format in the sign-off area:
104
105.. code-block:: none
106
107     Cc: <stable@vger.kernel.org> # 3.3.x: a1f84a3: sched: Check for idle
108     Cc: <stable@vger.kernel.org> # 3.3.x: 1b9508f: sched: Rate-limit newidle
109     Cc: <stable@vger.kernel.org> # 3.3.x: fd21073: sched: Fix affinity logic
110     Cc: <stable@vger.kernel.org> # 3.3.x
111     Signed-off-by: Ingo Molnar <mingo@elte.hu>
112
113The tag sequence has the meaning of:
114
115.. code-block:: none
116
117     git cherry-pick a1f84a3
118     git cherry-pick 1b9508f
119     git cherry-pick fd21073
120     git cherry-pick <this commit>
121
122Also, some patches may have kernel version prerequisites.  This can be
123specified in the following format in the sign-off area:
124
125.. code-block:: none
126
127     Cc: <stable@vger.kernel.org> # 3.3.x
128
129The tag has the meaning of:
130
131.. code-block:: none
132
133     git cherry-pick <this commit>
134
135For each "-stable" tree starting with the specified version.
136
137Following the submission:
138
139 - The sender will receive an ACK when the patch has been accepted into the
140   queue, or a NAK if the patch is rejected.  This response might take a few
141   days, according to the developer's schedules.
142 - If accepted, the patch will be added to the -stable queue, for review by
143   other developers and by the relevant subsystem maintainer.
144
145
146Review cycle
147------------
148
149 - When the -stable maintainers decide for a review cycle, the patches will be
150   sent to the review committee, and the maintainer of the affected area of
151   the patch (unless the submitter is the maintainer of the area) and CC: to
152   the linux-kernel mailing list.
153 - The review committee has 48 hours in which to ACK or NAK the patch.
154 - If the patch is rejected by a member of the committee, or linux-kernel
155   members object to the patch, bringing up issues that the maintainers and
156   members did not realize, the patch will be dropped from the queue.
157 - At the end of the review cycle, the ACKed patches will be added to the
158   latest -stable release, and a new -stable release will happen.
159 - Security patches will be accepted into the -stable tree directly from the
160   security kernel team, and not go through the normal review cycle.
161   Contact the kernel security team for more details on this procedure.
162
163Trees
164-----
165
166 - The queues of patches, for both completed versions and in progress
167   versions can be found at:
168
169	https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git
170
171 - The finalized and tagged releases of all stable kernels can be found
172   in separate branches per version at:
173
174	https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
175
176
177Review committee
178----------------
179
180 - This is made up of a number of kernel developers who have volunteered for
181   this task, and a few that haven't.
182