1 .. _stable_kernel_rules: 1 .. _stable_kernel_rules:
2 2
3 Everything you ever wanted to know about Linux 3 Everything you ever wanted to know about Linux -stable releases
4 ============================================== 4 ===============================================================
5 5
6 Rules on what kind of patches are accepted, an 6 Rules on what kind of patches are accepted, and which ones are not, into the
7 "-stable" tree: 7 "-stable" tree:
8 8
9 - It or an equivalent fix must already exist i !! 9 - It or an equivalent fix must already exist in Linus' tree (upstream).
10 - It must be obviously correct and tested. !! 10 - It must be obviously correct and tested.
11 - It cannot be bigger than 100 lines, with con !! 11 - It cannot be bigger than 100 lines, with context.
12 - It must follow the !! 12 - It must follow the
13 :ref:`Documentation/process/submitting-patch !! 13 :ref:`Documentation/process/submitting-patches.rst <submittingpatches>`
14 rules. !! 14 rules.
15 - It must either fix a real bug that bothers p !! 15 - It must either fix a real bug that bothers people or just add a device ID.
16 To elaborate on the former: !! 16 To elaborate on the former:
17 !! 17
18 - It fixes a problem like an oops, a hang, d !! 18 - It fixes a problem like an oops, a hang, data corruption, a real security
19 issue, a hardware quirk, a build error (bu !! 19 issue, a hardware quirk, a build error (but not for things marked
20 CONFIG_BROKEN), or some "oh, that's not go !! 20 CONFIG_BROKEN), or some "oh, that's not good" issue.
21 - Serious issues as reported by a user of a !! 21 - Serious issues as reported by a user of a distribution kernel may also
22 be considered if they fix a notable perfor !! 22 be considered if they fix a notable performance or interactivity issue.
23 As these fixes are not as obvious and have !! 23 As these fixes are not as obvious and have a higher risk of a subtle
24 regression they should only be submitted b !! 24 regression they should only be submitted by a distribution kernel
25 maintainer and include an addendum linking !! 25 maintainer and include an addendum linking to a bugzilla entry if it
26 exists and additional information on the u !! 26 exists and additional information on the user-visible impact.
27 - No "This could be a problem..." type of th !! 27 - No "This could be a problem..." type of things like a "theoretical race
28 condition", unless an explanation of how t !! 28 condition", unless an explanation of how the bug can be exploited is also
29 provided. !! 29 provided.
30 - No "trivial" fixes without benefit for use !! 30 - No "trivial" fixes without benefit for users (spelling changes, whitespace
31 cleanups, etc). !! 31 cleanups, etc).
32 32
33 33
34 Procedure for submitting patches to the -stabl 34 Procedure for submitting patches to the -stable tree
35 ---------------------------------------------- 35 ----------------------------------------------------
36 36
37 .. note:: 37 .. note::
38 38
39 Security patches should not be handled (sol 39 Security patches should not be handled (solely) by the -stable review
40 process but should follow the procedures in 40 process but should follow the procedures in
41 :ref:`Documentation/process/security-bugs.r 41 :ref:`Documentation/process/security-bugs.rst <securitybugs>`.
42 42
43 There are three options to submit a change to 43 There are three options to submit a change to -stable trees:
44 44
45 1. Add a 'stable tag' to the description of a !! 45 1. Add a 'stable tag' to the description of a patch you then submit for
46 mainline inclusion. !! 46 mainline inclusion.
47 2. Ask the stable team to pick up a patch alre !! 47 2. Ask the stable team to pick up a patch already mainlined.
48 3. Submit a patch to the stable team that is e !! 48 3. Submit a patch to the stable team that is equivalent to a change already
49 mainlined. !! 49 mainlined.
50 50
51 The sections below describe each of the option 51 The sections below describe each of the options in more detail.
52 52
53 :ref:`option_1` is **strongly** preferred, it 53 :ref:`option_1` is **strongly** preferred, it is the easiest and most common.
54 :ref:`option_2` is mainly meant for changes wh 54 :ref:`option_2` is mainly meant for changes where backporting was not considered
55 at the time of submission. :ref:`option_3` is 55 at the time of submission. :ref:`option_3` is an alternative to the two earlier
56 options for cases where a mainlined patch need 56 options for cases where a mainlined patch needs adjustments to apply in older
57 series (for example due to API changes). 57 series (for example due to API changes).
58 58
59 When using option 2 or 3 you can ask for your 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 o 60 stable series. When doing so, ensure the fix or an equivalent is applicable,
61 submitted, or already present in all newer sta 61 submitted, or already present in all newer stable trees still supported. This is
62 meant to prevent regressions that users might 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 backpo 63 e.g. a fix merged for 5.19-rc1 would be backported to 5.10.y, but not to 5.15.y.
64 64
65 .. _option_1: 65 .. _option_1:
66 66
67 Option 1 67 Option 1
68 ******** 68 ********
69 69
70 To have a patch you submit for mainline inclus 70 To have a patch you submit for mainline inclusion later automatically picked up
71 for stable trees, add this tag in the sign-off !! 71 for stable trees, add the tag
72 72
73 Cc: stable@vger.kernel.org !! 73 .. code-block:: none
74 74
75 Use ``Cc: stable@kernel.org`` instead when fix !! 75 Cc: stable@vger.kernel.org
76 it reduces the chance of accidentally exposing <<
77 'git send-email', as mails sent to that addres <<
78 76
79 Once the patch is mainlined it will be applied !! 77 in the sign-off area. Once the patch is mainlined it will be applied to the
80 anything else needing to be done by the author !! 78 stable tree without anything else needing to be done by the author or
>> 79 subsystem maintainer.
81 80
82 To send additional instructions to the stable !! 81 To sent additional instructions to the stable team, use a shell-style inline
83 comment to pass arbitrary or predefined notes: !! 82 comment:
84 83
85 * Specify any additional patch prerequisites f !! 84 * To specify any additional patch prerequisites for cherry picking use the
>> 85 following format in the sign-off area:
86 86
87 Cc: <stable@vger.kernel.org> # 3.3.x: a1f84 !! 87 .. code-block:: none
88 Cc: <stable@vger.kernel.org> # 3.3.x: 1b950 <<
89 Cc: <stable@vger.kernel.org> # 3.3.x: fd210 <<
90 Cc: <stable@vger.kernel.org> # 3.3.x <<
91 Signed-off-by: Ingo Molnar <mingo@elte.hu> <<
92 88
93 The tag sequence has the meaning of:: !! 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>
94 94
95 git cherry-pick a1f84a3 !! 95 The tag sequence has the meaning of:
96 git cherry-pick 1b9508f <<
97 git cherry-pick fd21073 <<
98 git cherry-pick <this commit> <<
99 96
100 Note that for a patch series, you do not hav !! 97 .. code-block:: none
101 patches present in the series itself. For ex <<
102 patch series:: <<
103 98
104 patch1 !! 99 git cherry-pick a1f84a3
105 patch2 !! 100 git cherry-pick 1b9508f
>> 101 git cherry-pick fd21073
>> 102 git cherry-pick <this commit>
106 103
107 where patch2 depends on patch1, you do not h !! 104 * For patches that may have kernel version prerequisites specify them using
108 prerequisite of patch2 if you have already m !! 105 the following format in the sign-off area:
109 inclusion. <<
110 106
111 * Point out kernel version prerequisites:: !! 107 .. code-block:: none
112 108
113 Cc: <stable@vger.kernel.org> # 3.3.x !! 109 Cc: <stable@vger.kernel.org> # 3.3.x
114 110
115 The tag has the meaning of:: !! 111 The tag has the meaning of:
116 112
117 git cherry-pick <this commit> !! 113 .. code-block:: none
118 114
119 For each "-stable" tree starting with the sp !! 115 git cherry-pick <this commit>
120 116
121 Note, such tagging is unnecessary if the sta !! 117 For each "-stable" tree starting with the specified version.
122 appropriate versions from Fixes: tags. <<
123 118
124 * Delay pick up of patches:: !! 119 Note, such tagging is unnecessary if the stable team can derive the
>> 120 appropriate versions from Fixes: tags.
125 121
126 Cc: <stable@vger.kernel.org> # after -rc3 !! 122 * To delay pick up of patches, use the following format:
127 123
128 * Point out known problems:: !! 124 .. code-block:: none
129 125
130 Cc: <stable@vger.kernel.org> # see patch de !! 126 Cc: <stable@vger.kernel.org> # after 4 weeks in mainline
131 127
132 There furthermore is a variant of the stable t !! 128 * For any other requests, just add a note to the stable tag. This for example
133 team's backporting tools (e.g AUTOSEL or scrip !! 129 can be used to point out known problems:
134 containing a 'Fixes:' tag) ignore a change:: <<
135 130
136 Cc: <stable+noautosel@kernel.org> # reason !! 131 .. code-block:: none
>> 132
>> 133 Cc: <stable@vger.kernel.org> # see patch description, needs adjustments for <= 6.3
137 134
138 .. _option_2: 135 .. _option_2:
139 136
140 Option 2 137 Option 2
141 ******** 138 ********
142 139
143 If the patch already has been merged to mainli 140 If the patch already has been merged to mainline, send an email to
144 stable@vger.kernel.org containing the subject 141 stable@vger.kernel.org containing the subject of the patch, the commit ID,
145 why you think it should be applied, and what k 142 why you think it should be applied, and what kernel versions you wish it to
146 be applied to. 143 be applied to.
147 144
148 .. _option_3: 145 .. _option_3:
149 146
150 Option 3 147 Option 3
151 ******** 148 ********
152 149
153 Send the patch, after verifying that it follow 150 Send the patch, after verifying that it follows the above rules, to
154 stable@vger.kernel.org and mention the kernel 151 stable@vger.kernel.org and mention the kernel versions you wish it to be applied
155 to. When doing so, you must note the upstream 152 to. When doing so, you must note the upstream commit ID in the changelog of your
156 submission with a separate line above the comm !! 153 submission with a separate line above the commit text, like this:
>> 154
>> 155 .. code-block:: none
>> 156
>> 157 commit <sha1> upstream.
157 158
158 commit <sha1> upstream. !! 159 or alternatively:
159 160
160 Or alternatively:: !! 161 .. code-block:: none
161 162
162 [ Upstream commit <sha1> ] !! 163 [ Upstream commit <sha1> ]
163 164
164 If the submitted patch deviates from the origi 165 If the submitted patch deviates from the original upstream patch (for example
165 because it had to be adjusted for the older AP 166 because it had to be adjusted for the older API), this must be very clearly
166 documented and justified in the patch descript 167 documented and justified in the patch description.
167 168
168 169
169 Following the submission 170 Following the submission
170 ------------------------ 171 ------------------------
171 172
172 The sender will receive an ACK when the patch 173 The sender will receive an ACK when the patch has been accepted into the
173 queue, or a NAK if the patch is rejected. Thi 174 queue, or a NAK if the patch is rejected. This response might take a few
174 days, according to the schedules of the stable 175 days, according to the schedules of the stable team members.
175 176
176 If accepted, the patch will be added to the -s 177 If accepted, the patch will be added to the -stable queue, for review by other
177 developers and by the relevant subsystem maint 178 developers and by the relevant subsystem maintainer.
178 179
179 180
180 Review cycle 181 Review cycle
181 ------------ 182 ------------
182 183
183 - When the -stable maintainers decide for a re !! 184 - When the -stable maintainers decide for a review cycle, the patches will be
184 sent to the review committee, and the mainta !! 185 sent to the review committee, and the maintainer of the affected area of
185 the patch (unless the submitter is the maint !! 186 the patch (unless the submitter is the maintainer of the area) and CC: to
186 the linux-kernel mailing list. !! 187 the linux-kernel mailing list.
187 - The review committee has 48 hours in which t !! 188 - The review committee has 48 hours in which to ACK or NAK the patch.
188 - If the patch is rejected by a member of the !! 189 - If the patch is rejected by a member of the committee, or linux-kernel
189 members object to the patch, bringing up iss !! 190 members object to the patch, bringing up issues that the maintainers and
190 members did not realize, the patch will be d !! 191 members did not realize, the patch will be dropped from the queue.
191 - The ACKed patches will be posted again as pa !! 192 - The ACKed patches will be posted again as part of release candidate (-rc)
192 to be tested by developers and testers. !! 193 to be tested by developers and testers.
193 - Usually only one -rc release is made, howeve !! 194 - Usually only one -rc release is made, however if there are any outstanding
194 issues, some patches may be modified or drop !! 195 issues, some patches may be modified or dropped or additional patches may
195 be queued. Additional -rc releases are then !! 196 be queued. Additional -rc releases are then released and tested until no
196 issues are found. !! 197 issues are found.
197 - Responding to the -rc releases can be done o !! 198 - Responding to the -rc releases can be done on the mailing list by sending
198 a "Tested-by:" email with any testing inform !! 199 a "Tested-by:" email with any testing information desired. The "Tested-by:"
199 tags will be collected and added to the rele !! 200 tags will be collected and added to the release commit.
200 - At the end of the review cycle, the new -sta !! 201 - At the end of the review cycle, the new -stable release will be released
201 containing all the queued and tested patches !! 202 containing all the queued and tested patches.
202 - Security patches will be accepted into the - !! 203 - Security patches will be accepted into the -stable tree directly from the
203 security kernel team, and not go through the !! 204 security kernel team, and not go through the normal review cycle.
204 Contact the kernel security team for more de !! 205 Contact the kernel security team for more details on this procedure.
205 206
206 207
207 Trees 208 Trees
208 ----- 209 -----
209 210
210 - The queues of patches, for both completed ve !! 211 - The queues of patches, for both completed versions and in progress
211 versions can be found at: !! 212 versions can be found at:
212 213
213 https://git.kernel.org/pub/scm/linux/kerne !! 214 https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git
214 215
215 - The finalized and tagged releases of all sta !! 216 - The finalized and tagged releases of all stable kernels can be found
216 in separate branches per version at: !! 217 in separate branches per version at:
217 218
218 https://git.kernel.org/pub/scm/linux/kerne !! 219 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
219 220
220 - The release candidate of all stable kernel v !! 221 - The release candidate of all stable kernel versions can be found at:
221 222
222 https://git.kernel.org/pub/scm/linux/kerne !! 223 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/
223 224
224 .. warning:: !! 225 .. warning::
225 The -stable-rc tree is a snapshot in time !! 226 The -stable-rc tree is a snapshot in time of the stable-queue tree and
226 will change frequently, hence will be reb !! 227 will change frequently, hence will be rebased often. It should only be
227 used for testing purposes (e.g. to be con !! 228 used for testing purposes (e.g. to be consumed by CI systems).
228 229
229 230
230 Review committee 231 Review committee
231 ---------------- 232 ----------------
232 233
233 - This is made up of a number of kernel develo !! 234 - This is made up of a number of kernel developers who have volunteered for
234 this task, and a few that haven't. !! 235 this task, and a few that haven't.
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