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 Linux mainline (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: 44 451. Add a 'stable tag' to the description of a patch you then submit for 46 mainline inclusion. 472. Ask the stable team to pick up a patch already mainlined. 483. 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 this tag in the sign-off area:: 72 73 Cc: [email protected] 74 75Use ``Cc: [email protected]`` instead when fixing unpublished vulnerabilities: 76it reduces the chance of accidentally exposing the fix to the public by way of 77'git send-email', as mails sent to that address are not delivered anywhere. 78 79Once the patch is mainlined it will be applied to the stable tree without 80anything else needing to be done by the author or subsystem maintainer. 81 82To sent additional instructions to the stable team, use a shell-style inline 83comment to pass arbitrary or predefined notes: 84 85* Specify any additional patch prerequisites for cherry picking:: 86 87 Cc: <[email protected]> # 3.3.x: a1f84a3: sched: Check for idle 88 Cc: <[email protected]> # 3.3.x: 1b9508f: sched: Rate-limit newidle 89 Cc: <[email protected]> # 3.3.x: fd21073: sched: Fix affinity logic 90 Cc: <[email protected]> # 3.3.x 91 Signed-off-by: Ingo Molnar <[email protected]> 92 93 The tag sequence has the meaning of:: 94 95 git cherry-pick a1f84a3 96 git cherry-pick 1b9508f 97 git cherry-pick fd21073 98 git cherry-pick <this commit> 99 100 Note that for a patch series, you do not have to list as prerequisites the 101 patches present in the series itself. For example, if you have the following 102 patch series:: 103 104 patch1 105 patch2 106 107 where patch2 depends on patch1, you do not have to list patch1 as 108 prerequisite of patch2 if you have already marked patch1 for stable 109 inclusion. 110 111* Point out kernel version prerequisites:: 112 113 Cc: <[email protected]> # 3.3.x 114 115 The tag has the meaning of:: 116 117 git cherry-pick <this commit> 118 119 For each "-stable" tree starting with the specified version. 120 121 Note, such tagging is unnecessary if the stable team can derive the 122 appropriate versions from Fixes: tags. 123 124* Delay pick up of patches:: 125 126 Cc: <[email protected]> # after -rc3 127 128* Point out known problems:: 129 130 Cc: <[email protected]> # see patch description, needs adjustments for <= 6.3 131 132.. _option_2: 133 134Option 2 135******** 136 137If the patch already has been merged to mainline, send an email to 138[email protected] containing the subject of the patch, the commit ID, 139why you think it should be applied, and what kernel versions you wish it to 140be applied to. 141 142.. _option_3: 143 144Option 3 145******** 146 147Send the patch, after verifying that it follows the above rules, to 148[email protected] and mention the kernel versions you wish it to be applied 149to. When doing so, you must note the upstream commit ID in the changelog of your 150submission with a separate line above the commit text, like this:: 151 152 commit <sha1> upstream. 153 154Or alternatively:: 155 156 [ Upstream commit <sha1> ] 157 158If the submitted patch deviates from the original upstream patch (for example 159because it had to be adjusted for the older API), this must be very clearly 160documented and justified in the patch description. 161 162 163Following the submission 164------------------------ 165 166The sender will receive an ACK when the patch has been accepted into the 167queue, or a NAK if the patch is rejected. This response might take a few 168days, according to the schedules of the stable team members. 169 170If accepted, the patch will be added to the -stable queue, for review by other 171developers and by the relevant subsystem maintainer. 172 173 174Review cycle 175------------ 176 177- When the -stable maintainers decide for a review cycle, the patches will be 178 sent to the review committee, and the maintainer of the affected area of 179 the patch (unless the submitter is the maintainer of the area) and CC: to 180 the linux-kernel mailing list. 181- The review committee has 48 hours in which to ACK or NAK the patch. 182- If the patch is rejected by a member of the committee, or linux-kernel 183 members object to the patch, bringing up issues that the maintainers and 184 members did not realize, the patch will be dropped from the queue. 185- The ACKed patches will be posted again as part of release candidate (-rc) 186 to be tested by developers and testers. 187- Usually only one -rc release is made, however if there are any outstanding 188 issues, some patches may be modified or dropped or additional patches may 189 be queued. Additional -rc releases are then released and tested until no 190 issues are found. 191- Responding to the -rc releases can be done on the mailing list by sending 192 a "Tested-by:" email with any testing information desired. The "Tested-by:" 193 tags will be collected and added to the release commit. 194- At the end of the review cycle, the new -stable release will be released 195 containing all the queued and tested patches. 196- Security patches will be accepted into the -stable tree directly from the 197 security kernel team, and not go through the normal review cycle. 198 Contact the kernel security team for more details on this procedure. 199 200 201Trees 202----- 203 204- The queues of patches, for both completed versions and in progress 205 versions can be found at: 206 207 https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git 208 209- The finalized and tagged releases of all stable kernels can be found 210 in separate branches per version at: 211 212 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git 213 214- The release candidate of all stable kernel versions can be found at: 215 216 https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/ 217 218 .. warning:: 219 The -stable-rc tree is a snapshot in time of the stable-queue tree and 220 will change frequently, hence will be rebased often. It should only be 221 used for testing purposes (e.g. to be consumed by CI systems). 222 223 224Review committee 225---------------- 226 227- This is made up of a number of kernel developers who have volunteered for 228 this task, and a few that haven't. 229