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 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. 12 - It must follow the 13 :ref:`Documentation/process/submitting-patches.rst <submittingpatches>` 14 rules. 15 - It must either fix a real bug that bothers people or just add a device ID. 16 To elaborate on the former: 17 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 29 provided. 30 - No "trivial" fixes without benefit for users (spelling changes, whitespace 31 cleanups, etc). 32 33 34Procedure for submitting patches to the -stable tree 35---------------------------------------------------- 36 37.. note:: 38 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>`. 42 43There are three options to submit a change to -stable trees: 44 45 1. Add a 'stable tag' to the description of a patch you then submit for 46 mainline inclusion. 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 49 mainlined. 50 51The sections below describe each of the options in more detail. 52 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 55at the time of submission. :ref:`option_3` is an alternative to the two earlier 56options for cases where a mainlined patch needs adjustments to apply in older 57series (for example due to API changes). 58 59When using option 2 or 3 you can ask for your change to be included in specific 60stable series. When doing so, ensure the fix or an equivalent is applicable, 61submitted, or already present in all newer stable trees still supported. This is 62meant to prevent regressions that users might later encounter on updating, if 63e.g. a fix merged for 5.19-rc1 would be backported to 5.10.y, but not to 5.15.y. 64 65.. _option_1: 66 67Option 1 68******** 69 70To have a patch you submit for mainline inclusion later automatically picked up 71for stable trees, add the tag 72 73.. code-block:: none 74 75 Cc: stable@vger.kernel.org 76 77in the sign-off area. Once the patch is mainlined it will be applied to the 78stable tree without anything else needing to be done by the author or 79subsystem maintainer. 80 81To sent additional instructions to the stable team, use a shell-style inline 82comment: 83 84 * To specify any additional patch prerequisites for cherry picking use the 85 following format in the sign-off area: 86 87 .. code-block:: none 88 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 95 The tag sequence has the meaning of: 96 97 .. code-block:: none 98 99 git cherry-pick a1f84a3 100 git cherry-pick 1b9508f 101 git cherry-pick fd21073 102 git cherry-pick <this commit> 103 104 * For patches that may have kernel version prerequisites specify them using 105 the following format in the sign-off area: 106 107 .. code-block:: none 108 109 Cc: <stable@vger.kernel.org> # 3.3.x 110 111 The tag has the meaning of: 112 113 .. code-block:: none 114 115 git cherry-pick <this commit> 116 117 For each "-stable" tree starting with the specified version. 118 119 Note, such tagging is unnecessary if the stable team can derive the 120 appropriate versions from Fixes: tags. 121 122 * To delay pick up of patches, use the following format: 123 124 .. code-block:: none 125 126 Cc: <stable@vger.kernel.org> # after 4 weeks in mainline 127 128 * For any other requests, just add a note to the stable tag. This for example 129 can be used to point out known problems: 130 131 .. code-block:: none 132 133 Cc: <stable@vger.kernel.org> # see patch description, needs adjustments for <= 6.3 134 135.. _option_2: 136 137Option 2 138******** 139 140If the patch already has been merged to mainline, send an email to 141stable@vger.kernel.org containing the subject of the patch, the commit ID, 142why you think it should be applied, and what kernel versions you wish it to 143be applied to. 144 145.. _option_3: 146 147Option 3 148******** 149 150Send the patch, after verifying that it follows the above rules, to 151stable@vger.kernel.org and mention the kernel versions you wish it to be applied 152to. When doing so, you must note the upstream commit ID in the changelog of your 153submission with a separate line above the commit text, like this: 154 155.. code-block:: none 156 157 commit <sha1> upstream. 158 159or alternatively: 160 161.. code-block:: none 162 163 [ Upstream commit <sha1> ] 164 165If the submitted patch deviates from the original upstream patch (for example 166because it had to be adjusted for the older API), this must be very clearly 167documented and justified in the patch description. 168 169 170Following the submission 171------------------------ 172 173The sender will receive an ACK when the patch has been accepted into the 174queue, or a NAK if the patch is rejected. This response might take a few 175days, according to the schedules of the stable team members. 176 177If accepted, the patch will be added to the -stable queue, for review by other 178developers and by the relevant subsystem maintainer. 179 180 181Review cycle 182------------ 183 184 - When the -stable maintainers decide for a review cycle, the patches will be 185 sent to the review committee, and the maintainer of the affected area of 186 the patch (unless the submitter is the maintainer of the area) and CC: to 187 the linux-kernel mailing list. 188 - The review committee has 48 hours in which to ACK or NAK the patch. 189 - If the patch is rejected by a member of the committee, or linux-kernel 190 members object to the patch, bringing up issues that the maintainers and 191 members did not realize, the patch will be dropped from the queue. 192 - The ACKed patches will be posted again as part of release candidate (-rc) 193 to be tested by developers and testers. 194 - Usually only one -rc release is made, however if there are any outstanding 195 issues, some patches may be modified or dropped or additional patches may 196 be queued. Additional -rc releases are then released and tested until no 197 issues are found. 198 - Responding to the -rc releases can be done on the mailing list by sending 199 a "Tested-by:" email with any testing information desired. The "Tested-by:" 200 tags will be collected and added to the release commit. 201 - At the end of the review cycle, the new -stable release will be released 202 containing all the queued and tested patches. 203 - Security patches will be accepted into the -stable tree directly from the 204 security kernel team, and not go through the normal review cycle. 205 Contact the kernel security team for more details on this procedure. 206 207 208Trees 209----- 210 211 - The queues of patches, for both completed versions and in progress 212 versions can be found at: 213 214 https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git 215 216 - The finalized and tagged releases of all stable kernels can be found 217 in separate branches per version at: 218 219 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git 220 221 - The release candidate of all stable kernel versions can be found at: 222 223 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/ 224 225 .. warning:: 226 The -stable-rc tree is a snapshot in time of the stable-queue tree and 227 will change frequently, hence will be rebased often. It should only be 228 used for testing purposes (e.g. to be consumed by CI systems). 229 230 231Review committee 232---------------- 233 234 - This is made up of a number of kernel developers who have volunteered for 235 this task, and a few that haven't. 236