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1 | .. _reportingbugs: |
2 | ||
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3 | .. note:: |
4 | ||
5 | This document is obsolete, and will be replaced by | |
6 | 'Documentation/admin-guide/reporting-issues.rst' in the near future. | |
7 | ||
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8 | Reporting bugs |
9 | ++++++++++++++ | |
10 | ||
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11 | Background |
12 | ========== | |
13 | ||
14 | The upstream Linux kernel maintainers only fix bugs for specific kernel | |
15 | versions. Those versions include the current "release candidate" (or -rc) | |
16 | kernel, any "stable" kernel versions, and any "long term" kernels. | |
17 | ||
18 | Please see https://www.kernel.org/ for a list of supported kernels. Any | |
19 | kernel marked with [EOL] is "end of life" and will not have any fixes | |
20 | backported to it. | |
21 | ||
11f0090e | 22 | If you've found a bug on a kernel version that isn't listed on kernel.org, |
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23 | contact your Linux distribution or embedded vendor for support. |
24 | Alternatively, you can attempt to run one of the supported stable or -rc | |
25 | kernels, and see if you can reproduce the bug on that. It's preferable | |
26 | to reproduce the bug on the latest -rc kernel. | |
27 | ||
28 | ||
29 | How to report Linux kernel bugs | |
30 | =============================== | |
31 | ||
32 | ||
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33 | Identify the problematic subsystem |
34 | ---------------------------------- | |
35 | ||
36 | Identifying which part of the Linux kernel might be causing your issue | |
37 | increases your chances of getting your bug fixed. Simply posting to the | |
38 | generic linux-kernel mailing list (LKML) may cause your bug report to be | |
39 | lost in the noise of a mailing list that gets 1000+ emails a day. | |
40 | ||
41 | Instead, try to figure out which kernel subsystem is causing the issue, | |
42 | and email that subsystem's maintainer and mailing list. If the subsystem | |
43 | maintainer doesn't answer, then expand your scope to mailing lists like | |
44 | LKML. | |
45 | ||
46 | ||
47 | Identify who to notify | |
48 | ---------------------- | |
49 | ||
50 | Once you know the subsystem that is causing the issue, you should send a | |
51 | bug report. Some maintainers prefer bugs to be reported via bugzilla | |
52 | (https://bugzilla.kernel.org), while others prefer that bugs be reported | |
53 | via the subsystem mailing list. | |
54 | ||
55 | To find out where to send an emailed bug report, find your subsystem or | |
56 | device driver in the MAINTAINERS file. Search in the file for relevant | |
57 | entries, and send your bug report to the person(s) listed in the "M:" | |
58 | lines, making sure to Cc the mailing list(s) in the "L:" lines. When the | |
59 | maintainer replies to you, make sure to 'Reply-all' in order to keep the | |
60 | public mailing list(s) in the email thread. | |
61 | ||
62 | If you know which driver is causing issues, you can pass one of the driver | |
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63 | files to the get_maintainer.pl script:: |
64 | ||
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65 | perl scripts/get_maintainer.pl -f <filename> |
66 | ||
67 | If it is a security bug, please copy the Security Contact listed in the | |
68 | MAINTAINERS file. They can help coordinate bugfix and disclosure. See | |
8c27ceff | 69 | :ref:`Documentation/admin-guide/security-bugs.rst <securitybugs>` for more information. |
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70 | |
71 | If you can't figure out which subsystem caused the issue, you should file | |
72 | a bug in kernel.org bugzilla and send email to | |
73 | linux-kernel@vger.kernel.org, referencing the bugzilla URL. (For more | |
74 | information on the linux-kernel mailing list see | |
2d457d55 | 75 | http://vger.kernel.org/lkml/). |
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76 | |
77 | ||
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78 | Tips for reporting bugs |
79 | ----------------------- | |
80 | ||
81 | If you haven't reported a bug before, please read: | |
82 | ||
93431e06 | 83 | https://www.chiark.greenend.org.uk/~sgtatham/bugs.html |
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84 | |
85 | http://www.catb.org/esr/faqs/smart-questions.html | |
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86 | |
87 | It's REALLY important to report bugs that seem unrelated as separate email | |
88 | threads or separate bugzilla entries. If you report several unrelated | |
89 | bugs at once, it's difficult for maintainers to tease apart the relevant | |
90 | data. | |
91 | ||
1da177e4 | 92 | |
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93 | Gather information |
94 | ------------------ | |
3b12c21a | 95 | |
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96 | The most important information in a bug report is how to reproduce the |
97 | bug. This includes system information, and (most importantly) | |
98 | step-by-step instructions for how a user can trigger the bug. | |
3b12c21a | 99 | |
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100 | If the failure includes an "OOPS:", take a picture of the screen, capture |
101 | a netconsole trace, or type the message from your screen into the bug | |
3ba9b1b8 | 102 | report. Please read "Documentation/admin-guide/bug-hunting.rst" before posting your |
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103 | bug report. This explains what you should do with the "Oops" information |
104 | to make it useful to the recipient. | |
1da177e4 | 105 | |
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106 | This is a suggested format for a bug report sent via email or bugzilla. |
107 | Having a standardized bug report form makes it easier for you not to | |
9dcbb32f | 108 | overlook things, and easier for the developers to find the pieces of |
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109 | information they're really interested in. If some information is not |
110 | relevant to your bug, feel free to exclude it. | |
1da177e4 | 111 | |
3b12c21a | 112 | First run the ver_linux script included as scripts/ver_linux, which |
1da177e4 | 113 | reports the version of some important subsystems. Run this script with |
20b786eb | 114 | the command ``awk -f scripts/ver_linux``. |
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115 | |
116 | Use that information to fill in all fields of the bug report form, and | |
117 | post it to the mailing list with a subject of "PROBLEM: <one line | |
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118 | summary from [1.]>" for easy identification by the developers:: |
119 | ||
120 | [1.] One line summary of the problem: | |
121 | [2.] Full description of the problem/report: | |
122 | [3.] Keywords (i.e., modules, networking, kernel): | |
123 | [4.] Kernel information | |
124 | [4.1.] Kernel version (from /proc/version): | |
125 | [4.2.] Kernel .config file: | |
126 | [5.] Most recent kernel version which did not have the bug: | |
127 | [6.] Output of Oops.. message (if applicable) with symbolic information | |
3ba9b1b8 | 128 | resolved (see Documentation/admin-guide/bug-hunting.rst) |
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129 | [7.] A small shell script or example program which triggers the |
130 | problem (if possible) | |
131 | [8.] Environment | |
132 | [8.1.] Software (add the output of the ver_linux script here) | |
133 | [8.2.] Processor information (from /proc/cpuinfo): | |
134 | [8.3.] Module information (from /proc/modules): | |
135 | [8.4.] Loaded driver and hardware information (/proc/ioports, /proc/iomem) | |
136 | [8.5.] PCI information ('lspci -vvv' as root) | |
137 | [8.6.] SCSI information (from /proc/scsi/scsi) | |
138 | [8.7.] Other information that might be relevant to the problem | |
139 | (please look in /proc and include all information that you | |
140 | think to be relevant): | |
141 | [X.] Other notes, patches, fixes, workarounds: | |
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142 | |
143 | ||
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144 | Follow up |
145 | ========= | |
146 | ||
147 | Expectations for bug reporters | |
148 | ------------------------------ | |
149 | ||
150 | Linux kernel maintainers expect bug reporters to be able to follow up on | |
151 | bug reports. That may include running new tests, applying patches, | |
152 | recompiling your kernel, and/or re-triggering your bug. The most | |
153 | frustrating thing for maintainers is for someone to report a bug, and then | |
154 | never follow up on a request to try out a fix. | |
155 | ||
156 | That said, it's still useful for a kernel maintainer to know a bug exists | |
157 | on a supported kernel, even if you can't follow up with retests. Follow | |
158 | up reports, such as replying to the email thread with "I tried the latest | |
159 | kernel and I can't reproduce my bug anymore" are also helpful, because | |
160 | maintainers have to assume silence means things are still broken. | |
161 | ||
162 | Expectations for kernel maintainers | |
163 | ----------------------------------- | |
164 | ||
165 | Linux kernel maintainers are busy, overworked human beings. Some times | |
166 | they may not be able to address your bug in a day, a week, or two weeks. | |
167 | If they don't answer your email, they may be on vacation, or at a Linux | |
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168 | conference. Check the conference schedule at https://LWN.net for more info: |
169 | ||
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170 | https://lwn.net/Calendar/ |
171 | ||
172 | In general, kernel maintainers take 1 to 5 business days to respond to | |
173 | bugs. The majority of kernel maintainers are employed to work on the | |
174 | kernel, and they may not work on the weekends. Maintainers are scattered | |
175 | around the world, and they may not work in your time zone. Unless you | |
176 | have a high priority bug, please wait at least a week after the first bug | |
177 | report before sending the maintainer a reminder email. | |
178 | ||
179 | The exceptions to this rule are regressions, kernel crashes, security holes, | |
180 | or userspace breakage caused by new kernel behavior. Those bugs should be | |
181 | addressed by the maintainers ASAP. If you suspect a maintainer is not | |
182 | responding to these types of bugs in a timely manner (especially during a | |
183 | merge window), escalate the bug to LKML and Linus Torvalds. | |
184 | ||
185 | Thank you! | |
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186 | |
187 | [Some of this is taken from Frohwalt Egerer's original linux-kernel FAQ] |