← Back to team overview

kernel-packages team mailing list archive

[Bug 1597419] Re: On __fget_light function issue


Can you provide some information on the status of the patch with regards
to getting it merged upstream? Has it been sent upstream, what sort of
feedback has it received, is it getting applied to a subsystem
maintainer's tree, etc?

People affected by this bug are probably wondering why the kernel team
doesn't just apply the patch and fix it. The reason is that the kernel
team is reluctant (not opposed) to apply any patch to a stable kernel
that is not from upstream. Applying patches that don't come from
upstream add greatly to the support of the kernel as other upstream
patches may touch the same area as the non-upstream patch and may
prevent them from applying cleanly.

To submit your patch, send your patch with the detailed
description/changelog and your Signoff (ending with Signed-off-by: your
name <email>), to the emails listed from ./scripts/get_maintainer.pl
drivers/SUBSYSTEM-DETAILS (the get_maintainer.pl is from the kernel
sources). Once you have sent the patch upstream and it's accepted,
please drop a note here so that we can cherry-pick/include the patch
into Ubuntu kernel.

** Changed in: linux (Ubuntu)
   Importance: Undecided => Medium

** Changed in: linux (Ubuntu)
       Status: Confirmed => Triaged

You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.

  On __fget_light function issue

Status in linux package in Ubuntu:

Bug description:
  Bellow is result of perf record:
  __fget_light  /proc/kcore                                                                                        
         │    ↓ je     30
         │      push   %rbp
         │      mov    %rsp,%rbp
         │      callq  0xffffffff8122a6a0
         │      test   %rax,%rax
         │    ↓ je     54
    0,83 │      or     $0x1,%rax
         │      pop    %rbp
         │    ← retq
         │30:   mov    0x20(%rax),%rax
    1,65 │      cmp    (%rax),%edi
    0,83 │    ↓ jae    51
    0,83 │      mov    0x8(%rax),%rax
    0,83 │      mov    %edi,%edi
         │      lea    (%rax,%rdi,8),%rax
    2,48 │      mov    (%rax),%rax
    2,48 │      test   %rax,%rax
         │    ↓ je     51
         │      test   %esi,0x44(%rax)
   70,25 │   ┌──jne    51
         │   │  repz   retq
         │51:└─→xor    %eax,%eax
         │    ← retq
         │54:   xor    %eax,%eax
         │      pop    %rbp
         │    ← retq
  and i attached one patch wich descrease from 70-100 cycles stall to 23 cycles stall on function.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: linux-image-4.4.0-28-generic 4.4.0-28.47
  ProcVersionSignature: Ubuntu 4.4.0-28.47-generic 4.4.13
  Uname: Linux 4.4.0-28-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2.1
  Architecture: amd64
   /dev/snd/controlC0:  asu        2742 F.... pulseaudio
  CurrentDesktop: MATE
  Date: Wed Jun 29 18:50:46 2016
  InstallationDate: Installed on 2016-04-29 (61 days ago)
  InstallationMedia: Ubuntu-Studio 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
   lo        no wireless extensions.
   enp1s0    no wireless extensions.
  MachineType: Olidata S.p.A. ALABAMA
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.4.0-28-generic root=/dev/mapper/192--168--0--108--vg-root ro
   linux-restricted-modules-4.4.0-28-generic N/A
   linux-backports-modules-4.4.0-28-generic  N/A
   linux-firmware                            1.157.1
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 07/08/2008
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: S0101
  dmi.board.asset.tag: To Be Filled By O.E.M.
  dmi.board.name: To be filled by O.E.M.
  dmi.board.vendor: To be filled by O.E.M.
  dmi.board.version: To be filled by O.E.M.
  dmi.chassis.asset.tag: To Be Filled By O.E.M.
  dmi.chassis.type: 3
  dmi.chassis.vendor: To Be Filled By O.E.M.
  dmi.chassis.version: To Be Filled By O.E.M.
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrS0101:bd07/08/2008:svnOlidataS.p.A.:pnALABAMA:pvrToBeFilledByO.E.M.:rvnTobefilledbyO.E.M.:rnTobefilledbyO.E.M.:rvrTobefilledbyO.E.M.:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
  dmi.product.name: ALABAMA
  dmi.product.version: To Be Filled By O.E.M.
  dmi.sys.vendor: Olidata S.p.A.

To manage notifications about this bug go to: