[Dell Latitude E7440] Wifi keeps dropping with Intel Wireless 7260

[Niels Holmgaard]

After the connection is dropped, a hardware switch disconnect/connect is necessary to re-establish connection, the connection does not automatically reappear. The problematic line in the dmesg output is:
wlan0: deauthenticated from 00:16:b6:01:69:74 (Reason: 7=CLASS3_FRAME_FROM_NONASSOC_STA)

The frequency of the problem drops considerably moving to a less congested channel, but it still happens - I am stationary at about 3 meters from the access point. Other devices (Android phones, iPad, other laptops) are connecting to the same access point with no problems at all.

Network controller [0280]: Intel Corporation Wireless 7260 [8086:08b1] (rev 73)
 Subsystem: Intel Corporation Dual Band Wireless-AC 7260 [8086:4470]

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: linux-image-3.16.0-24-generic 3.16.0-24.32
ProcVersionSignature: Ubuntu 3.16.0-24.32-generic 3.16.4
Uname: Linux 3.16.0-24-generic x86_64
ApportVersion: 2.14.7-0ubuntu8
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: niels 2502 F.... pulseaudio
 /dev/snd/controlC1: niels 2502 F.... pulseaudio
CurrentDesktop: Unity
Date: Tue Nov 25 21:24:21 2014
HibernationDevice: RESUME=UUID=fe0b3838-4f25-4296-a7c7-872862359ccf
InstallationDate: Installed on 2014-10-16 (40 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
MachineType: Dell Inc. Latitude E7440
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.16.0-24-generic root=UUID=28b33773-57cd-4cb6-bd65-1c2acadbd079 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.16.0-24-generic N/A
 linux-backports-modules-3.16.0-24-generic N/A
 linux-firmware 1.138
SourcePackage: linux
UpgradeStatus: Upgraded to utopic on 2014-10-25 (31 days ago)
dmi.bios.date: 06/26/2014
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A10
dmi.board.name: 03HFCG
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA10:bd06/26/2014:svnDellInc.:pnLatitudeE7440:pvr01:rvnDellInc.:rn03HFCG:rvrA00:cvnDellInc.:ct9:cvr:
dmi.product.name: Latitude E7440
dmi.product.version: 01
dmi.sys.vendor: Dell Inc.

[Niels Holmgaard (niels-holmgard)]

- but connection dropped twice while compiling this bug report. That is unusual, though - I now experience two or three drop-outs per day, before changing away from the most congested channel, I had at least one per hour.

The neighborhood is very crowded in the 2.4 GHz band.

[Brad Figg (brad-figg)]

This change was made by a bot.

[penalvch (penalvch)]

Niels Holmgaard, thank you for reporting this and helping make Ubuntu better. Could you please test the latest upstream kernel available from the very top line at the top of the page (the release names are irrelevant for testing, and please do not test the daily folder) following https://wiki.ubuntu.com/KernelMainlineBuilds ? It will allow additional upstream developers to examine the issue.

If the test did not allow you to test to the issue (ex. you couldn't boot into the OS) please make a comment in your report about this, and continue to test the next most recent kernel version until you can test to the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this bug is fixed in the mainline kernel, please add the following tags:
kernel-fixed-upstream
kernel-fixed-upstream-VERSION-NUMBER

where VERSION-NUMBER is the version number of the kernel you tested exactly shown as:
kernel-fixed-upstream-3.18-rc6

This can be done by clicking on the yellow circle with a black pencil icon next to the word Tags located at the bottom of the bug description.

If the mainline kernel does not fix this bug, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-VERSION-NUMBER

Once testing of the upstream kernel is complete, please mark this bug's Status as Confirmed. Please let us know your results. Thank you for your understanding.

[Jennifer Richards (jenny-borkbork)]

FYI, I seem to have this problem with my Dell XPS 13 (2014 Ubuntu Developer's Edition). This also has the Intel wifi chipset (Intel(R) Dual Band Wireless AC 7260, REV=0x144). I had the same error messages and very similar overall behavior.

I updated to the latest mainline kernel as suggested and I have not had a dropout since, which is probably 5 hours of active wifi over two days. Previously it was disconnecting every 5-15 minutes in a very low-traffic environment.

The working mainline kernel is: 3.18.0-031800rc7-generic
Previously I was having this problem with: 3.16.0-25-generic

Since I am not the original reporter and I have a slightly different configuration, I am not going to update the tags/status, but I suggest he try the kernel.

[penalvch (penalvch)]

Joey Richards, thank you for your comment. So your hardware and problem may be tracked, could you please file a new report with Ubuntu by executing the following in a terminal while booted into the default Ubuntu kernel (not a mainline one) via:
ubuntu-bug linux

For more on this, please read the official Ubuntu documentation:
Ubuntu Bug Control and Ubuntu Bug Squad: https://wiki.ubuntu.com/Bugs/BestPractices#X.2BAC8-Reporting.Focus_on_One_Issue
Ubuntu Kernel Team: https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies#Filing_Kernel_Bug_reports
https://wiki.ubuntu.com/Kernel/Policies/DuplicateBugs
Ubuntu Community: https://help.ubuntu.com/community/ReportingBugs#Bug_reporting_etiquette

When opening up the new report, please feel free to subscribe me to it.

As well, please do not announce in this report you created a new bug report.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

[Niels Holmgaard (niels-holmgard)]

I have been running 3.18 RC6 the last days with no drop-outs. Added the tags as requested.

[penalvch (penalvch)]

Niels Holmgaard, the next step is to fully reverse commit bisect from kernel 3.16 to 3.18-rc6 in order to identify the last bad commit, followed immediately by the first good one. Once this commit has been identified, then it may be reviewed as a candidate for backporting into your release. Could you please do this following https://wiki.ubuntu.com/Kernel/KernelBisection#How_do_I_reverse_bisect_the_upstream_kernel.3F ? Please note, finding adjacent kernel versions is not fully commit bisecting.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

[Niels Holmgaard (niels-holmgard)]

I have set up the git tree and successfully compiled and installed a few vanilla kernels. However, it seems that even the vanilla 3.16 also works - no dropouts in the last few evenings, where the Ubuntu 3.16.0.25 drops several times per hour.

I have tried to find the correspondence between the vanilla and Ubuntu kernels, but it seems that this list http://people.canonical.com/~kernel/info/kernel-version-map.html is not completely up to date. The 3.16 series is not shown.

I will keep testing, but I would appreciate to start the (quite time consuming) commit bisect from a known bad kernel. Could you point me to the correct starting point, please?

[penalvch (penalvch)]

Niels Holmgaard, you would need to test the kernels in the mainline list until you either find a known bad one, or you are well behind the 3.16 version.

[Niels Holmgaard (niels-holmgard)]

Thanks. I would still like to point out that the list http://people.canonical.com/~kernel/info/kernel-version-map.html is not up to date regarding kernel version 3.16-ubuntu, and that updating it could have saved some compilation hours in this case.

However, Vanilla 3.15 fails with the same error in dmesg, so the error is fixed in the upstream kernel between 3.15 and 3.16, and this commit did not make it into the ubuntu version 3.16.

I have now begun reverse commit bisecting between upstream kernels 3.15 and 3.16, but this will take some time to finish - each kernel build takes about an hour, and must be run at least a few hours to be certain if it is good or bad, so best case will be about a month from now.

I hope that this information can help someone - otherwise, for now just upgrade to upstream version 3.16 or later, and you should be good.

[Niels Holmgaard (niels-holmgard)]

Status after a few iterations, again in the hope that this can be useful to someone:

~/linux$ git bisect log
git bisect start
# good: [1860e379875dfe7271c649058aeddffe5afd9d0d] Linux 3.15
git bisect good 1860e379875dfe7271c649058aeddffe5afd9d0d
# bad: [19583ca584d6f574384e17fe7613dfaeadcdc4a6] Linux 3.16
git bisect bad 19583ca584d6f574384e17fe7613dfaeadcdc4a6
# good: [7b215de3d0abbc4f6daf2efd19e8809af0564490] Merge branch 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux into next
git bisect good 7b215de3d0abbc4f6daf2efd19e8809af0564490

- reverse bisecting, so good means that the fix is not in, and the wifi disconnects as detailed in the bug. Moving on...

[Niels Holmgaard (niels-holmgard)]

Did not disect to the bottom - released version 3.16.0-28 corrects the problem, so I assume that someone beat me to it.

Fixed and verified over the last few days by switching back and forth between -25 and -28. Wifi keeps dropping in -25, and stays stable overnight in -28.