Tyler, before you spend any time on this, I've already investigated and 
think it may actually be a bug in the core kernel FPU code.  I reported it 
on LKML with a tentative patch: https://lkml.org/lkml/2014/1/19/86 I 
haven't yet received any feedback or discussion from LKML; when I have a 
chance I was thinking of writing it up as a formal patch submission, in 
hopes that it would get more attention that way.  If you have any other 
ideas (about the bug itself or how to get it fixed), that would be great!

Thanks!

Nate

On Mon, 27 Jan 2014, Tyler Hicks wrote:

> Thanks for the great bug report, Maarten. I've linked it into the
> upstream eCryptfs tracker (also hosted on Launchpad) and I'll start
> looking into it.
>
> It initially feels like a bug in the aesni module, but that's just an
> early guess.
>
> ** Also affects: ecryptfs
>   Importance: Undecided
>       Status: New
>
> ** Changed in: ecryptfs
>     Assignee: (unassigned) => Tyler Hicks (tyhicks)
>
> ** Changed in: ecryptfs
>   Importance: Undecided => High
>
> -- 
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1265841
>
> Title:
>  kernel BUG at /build/buildd/linux-3.11.0/fs/buffer.c:1268!; RIP:
>  0010:[<ffffffff816e3efd>]  [<ffffffff816e3efd>]
>  check_irqs_on.part.11+0x4/0x6
>
> Status in eCryptfs:
>  New
> Status in “linux” package in Ubuntu:
>  Triaged
>
> Bug description:
>  This only happens when aesni_intel is loaded.
>
>  In my attempts to find an easy way to reproduce this bug:
>  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1265684
>  I actually found a very simple way to trigger a bug that is similar but not identical. I suspect that both bugs have the same cause: something in the kernel is disabling IRQs and the ext4 code will crash when this happens. The stack trace for this bug is different from the other one. This one appears to be less severe, the system is still usable after the crash, only the process that caused the crash will hang (uninterruptible sleep). This bug is 100% reproducible on both Ubuntu 13.10 with kernel 3.11.0 and Arch Linux with kernel 3.12.6.
>
>  The steps to reproduce the bug are based on this:
>  http://www.spinics.net/lists/linux-ext4/msg38949.html
>
>  * Set up an ecryptfs 'Private' folder in your home directory.
>  * In that directory, create a file called 'crashme.c' with the following code in it:
>  #include <assert.h>
>  int main() { assert(0); }
>
>  * Compile the program:
>  gcc -Wall crashme.c -o crashme
>
>  * Change the core dump pattern so core dumps are saved in the current directory:
>  echo "coredump-%p" | sudo tee /proc/sys/kernel/core_pattern
>
>  * Enable core dumps:
>  ulimit -c unlimited
>
>  * Make sure that you have a second terminal open to run dmesg, because you may not be able to do so later.
>  * Run 'crashme' - this will hang and trigger the bug:
>  ./crashme
>
>  ProblemType: Bug
>  DistroRelease: Ubuntu 13.10
>  Package: linux-image-3.11.0-15-generic 3.11.0-15.23
>  ProcVersionSignature: Ubuntu 3.11.0-15.23-generic 3.11.10
>  Uname: Linux 3.11.0-15-generic x86_64
>  NonfreeKernelModules: nvidia
>  ApportVersion: 2.12.5-0ubuntu2.2
>  Architecture: amd64
>  AudioDevicesInUse:
>   USER        PID ACCESS COMMAND
>   /dev/snd/controlC0:  maarten    1666 F.... lxpanel
>  CRDA: Error: [Errno 2] No such file or directory: 'iw'
>  Date: Fri Jan  3 15:58:24 2014
>  EcryptfsInUse: Yes
>  HibernationDevice: RESUME=UUID=bc17e234-da75-457f-b17c-22d9c0e27dd8
>  InstallationDate: Installed on 2013-12-28 (6 days ago)
>  InstallationMedia: Lubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
>  IwConfig:
>   eth0      no wireless extensions.
>
>   lo        no wireless extensions.
>  MachineType: Gigabyte Technology Co., Ltd. Z87X-D3H
>  MarkForUpload: True
>  ProcFB: 0 EFI VGA
>  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.11.0-15-generic.efi.signed root=UUID=5a8ae1fc-91bf-4ce0-8dea-a519976fd56b ro quiet splash vt.handoff=7
>  RelatedPackageVersions:
>   linux-restricted-modules-3.11.0-15-generic N/A
>   linux-backports-modules-3.11.0-15-generic  N/A
>   linux-firmware                             1.116
>  RfKill:
>
>  SourcePackage: linux
>  StagingDrivers: zram
>  UpgradeStatus: No upgrade log present (probably fresh install)
>  dmi.bios.date: 08/02/2013
>  dmi.bios.vendor: American Megatrends Inc.
>  dmi.bios.version: F7
>  dmi.board.asset.tag: To be filled by O.E.M.
>  dmi.board.name: Z87X-D3H-CF
>  dmi.board.vendor: Gigabyte Technology Co., Ltd.
>  dmi.board.version: x.x
>  dmi.chassis.asset.tag: To Be Filled By O.E.M.
>  dmi.chassis.type: 3
>  dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
>  dmi.chassis.version: To Be Filled By O.E.M.
>  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF7:bd08/02/2013:svnGigabyteTechnologyCo.,Ltd.:pnZ87X-D3H:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rnZ87X-D3H-CF:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvrToBeFilledByO.E.M.:
>  dmi.product.name: Z87X-D3H
>  dmi.product.version: To be filled by O.E.M.
>  dmi.sys.vendor: Gigabyte Technology Co., Ltd.
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ecryptfs/+bug/1265841/+subscriptions
>
>

-- 
Nate Eldredge
<email address hidden>