linux-traipu team mailing list archive

["Daniel Richard G." <skunk@xxxxxxxxxx>]

Okay, I've done a bit of digging on this using a debug build.

The problem is in the very first line of BackendImpl::MatchEntry():

    Addr address(data_->table[hash & mask_]);

data_->table[] is a memory-mapped array, backed by the file
~/.cache/chromium/Default/Cache/index (in my case). When my home
directory goes away due to my Kerberos authentication expiring, this
file is no longer accessible, and thus any attempt to read from its
mapping fails with SIGBUS.

Arguably, the fix would be to eliminate the use of memory-mapped files
from Chromium's disk-cache backend. Nowhere else in Chromium are files
in the user's home directory memory-mapped, so this wouldn't be such a
big deal. Indeed, I would make the case that mapping files in $HOME is a
bad idea precisely because of the potential for network filesystems to
cause this to yield SIGBUS errors. (Alternately, the signal could be
caught and handled appropriately, but this option did not appeal to the
Chromium developers.)

For now, I'm trying out Chromium's mostly-undocumented --disk-cache-dir
option as a workaround. By relocating the disk cache to a directory on
the local disk, I should be able to avoid this crash.

-- 
You received this bug notification because you are a member of UBUNTU -
AL - BR, which is subscribed to Chromium Browser.
https://bugs.launchpad.net/bugs/807611

Title:
  chromium-browser crashed with signal 7

Status in Chromium Browser:
  Unknown
Status in “chromium-browser” package in Ubuntu:
  New

Bug description:
  This crash occurred on a system in which the home directory is served
  out of AFS, at a time when my authentication had expired and so $HOME
  was inaccessible.

  ProblemType: Crash
  DistroRelease: Ubuntu 11.04
  Package: chromium-browser 12.0.742.112~r90304-0ubuntu0.11.04.1
  ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
  Uname: Linux 2.6.38-8-generic x86_64
  NonfreeKernelModules: openafs
  Architecture: amd64
  Date: Fri Jul  8 04:23:56 2011
  Desktop-Session:
   DESKTOP_SESSION = xfce
   XDG_CONFIG_DIRS = /etc/xdg/xdg-xubuntu:/etc/xdg:/etc/xdg
   XDG_DATA_DIRS = /usr/share/xubuntu:/usr/local/share:/usr/share
  Env:
   MOZ_PLUGIN_PATH = None
   LD_LIBRARY_PATH = None
  ExecutablePath: /usr/lib/chromium-browser/chromium-browser
  LocalLibraries: /afs/teragram.com/user/dgomez/.mozilla/plugins/libflashplayer.so
  ProcCmdline: /usr/lib/chromium-browser/chromium-browser
  ProcEnviron:
   
  Signal: 7
  SourcePackage: chromium-browser
  StacktraceTop:
   ?? ()
   ?? ()
   ?? ()
   ?? ()
   ?? ()
  Title: chromium-browser crashed with signal 7
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm audio cdrom dialout floppy plugdev vboxusers video
  chromium-default: CHROMIUM_FLAGS=""

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