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

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