openjdk team mailing list archive

[Xerxes Rånby <xerxes@xxxxxxxxx>]

The best way to track this kernel lock bug are probably to recompile a
kernel with lockdep enabled.

(11:40:44) xranby: mjw: can systemtap help diagnose kernel locks? i would like to know what part of the kernel are holding a &mm->mmap_sem semaphore
(11:42:20) xranby: all i currently know are all parts of the kernel gets stuck waiting for this semaphre to get released :/
(11:45:29) mjw: xranby, for that kind of kernel lock issue I would use lockdep
(11:47:38) mjw: https://www.kernel.org/doc/Documentation/lockdep-design.txt
(11:48:13) mjw: xranby, that does mean you want a kernel build with lockdep enabled
(11:48:17) mjw: which is slow
(11:48:30) xranby: sounds like a reasonable way to debug this
(11:48:45) xranby: http://lwn.net/Articles/321663/ found this lwn article on the subject as well
(11:48:55) xranby: thank you for the heads up of lockdep existance
(11:49:15) mjw: http://linuxplumbersconf.org/2011/ocw//system/presentations/153/original/lockdep-plumbers-2011.odp
(11:49:31) mjw: It is not as cool as using systemtap of course :)
(11:50:10) mjw: But for systemtap to help you with this issue you have to have some hint already where you suspect the problem might be
(11:50:21) mjw: if so, then you can set probes on the suspected functions
(11:50:35) mjw: and trace how/when/in-which-order they are called
(11:51:05) mjw: lockdep automates that for you (with the downside of having to recompile your kernel of course)

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https://bugs.launchpad.net/bugs/845158

Title:
  Frequent java task hang on ARM server

Status in “openjdk-6” package in Ubuntu:
  Confirmed

Bug description:
  I'm using an up-to-date oneiric ARM server image running jenkins -
  after a short period of time (< 1 hour) the server locks up - hard
  reboot and I can see these messages in the syslog:

  Sep  8 21:50:51 winehouse kernel: [ 7920.496795] INFO: task java:20973 blocked for more than 120 seconds.
  Sep  8 21:50:51 winehouse kernel: [ 7920.496795] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
  Sep  8 21:50:51 winehouse kernel: [ 7920.497009] java            D c05ca9e0     0 20973    561 0x00000000
  Sep  8 21:50:51 winehouse kernel: [ 7920.497222] [<c05ca9e0>] (schedule+0x540/0x618) from [<c05cc728>] (__down_read+0xc0/0xd8)
  Sep  8 21:50:51 winehouse kernel: [ 7920.497222] [<c05cc728>] (__down_read+0xc0/0xd8) from [<c05cf5e8>] (do_page_fault.part.2+0x80/0x1e0)
  Sep  8 21:50:51 winehouse kernel: [ 7920.497222] [<c05cf5e8>] (do_page_fault.part.2+0x80/0x1e0) from [<c05cf7e4>] (do_page_fault+0x9c/0xac)
  Sep  8 21:50:51 winehouse kernel: [ 7920.497222] [<c05cf7e4>] (do_page_fault+0x9c/0xac) from [<c004c410>] (do_DataAbort+0x34/0x98)
  Sep  8 21:50:51 winehouse kernel: [ 7920.497406] [<c004c410>] (do_DataAbort+0x34/0x98) from [<c05cd210>] (__dabt_svc+0x70/0xa0)
  Sep  8 21:50:51 winehouse kernel: [ 7920.497436] Exception stack(0xec91dec0 to 0xec91df08)
  Sep  8 21:50:51 winehouse kernel: [ 7920.497467] dec0: 56e0f000 56e12000 00000020 0000001f ef248040 56e110c0 56e0f44c ef248000
  Sep  8 21:50:51 winehouse kernel: [ 7920.497467] dee0: 00000000 ec91c000 00000000 56b4446c 56e11000 ec91df08 c00553d4 c005d198
  Sep  8 21:50:51 winehouse kernel: [ 7920.497497] df00: 800f0013 ffffffff
  Sep  8 21:50:51 winehouse kernel: [ 7920.497497] [<c05cd210>] (__dabt_svc+0x70/0xa0) from [<c005d198>] (v7_coherent_kern_range+0x1c/0x7c)
  Sep  8 21:50:51 winehouse kernel: [ 7920.497497] [<c005d198>] (v7_coherent_kern_range+0x1c/0x7c) from [<c00553d4>] (arm_syscall+0x140/0x294)
  Sep  8 21:50:51 winehouse kernel: [ 7920.497497] [<c00553d4>] (arm_syscall+0x140/0x294) from [<c0051220>] (ret_fast_syscall+0x0/0x30)

  Architecture: armel
  Date: Fri Sep  9 08:51:09 2011
  Dependencies:
   ca-certificates 20110502+nmu1
   ca-certificates-java 20110531
   coreutils 8.5-1ubuntu6
   debconf 1.5.40ubuntu1
   dpkg 1.16.0.3ubuntu3
   gcc-4.6-base 4.6.1-9ubuntu2
   icedtea-6-jre-jamvm 6b23~pre8-1ubuntu1
   java-common 0.42ubuntu1
   libacl1 2.2.51-3
   libattr1 1:2.4.46-3
   libavahi-client3 0.6.30-4ubuntu1
   libavahi-common-data 0.6.30-4ubuntu1
   libavahi-common3 0.6.30-4ubuntu1
   libbz2-1.0 1.0.5-6ubuntu1
   libc-bin 2.13-17ubuntu2
   libc6 2.13-17ubuntu2
   libcomerr2 1.41.14-1ubuntu3
   libcups2 1.5.0-5
   libdbus-1-3 1.4.14-1ubuntu1
   libfreetype6 2.4.4-2ubuntu1
   libgcc1 1:4.6.1-9ubuntu2
   libgcrypt11 1.5.0-1
   libgnutls26 2.10.5-1ubuntu3
   libgpg-error0 1.10-0.3ubuntu1
   libgssapi-krb5-2 1.9.1+dfsg-1ubuntu1
   libjpeg62 6b1-1ubuntu2
   libk5crypto3 1.9.1+dfsg-1ubuntu1
   libkeyutils1 1.4-6
   libkrb5-3 1.9.1+dfsg-1ubuntu1
   libkrb5support0 1.9.1+dfsg-1ubuntu1
   liblcms1 1.19.dfsg-1ubuntu1
   liblzma2 5.0.0-2
   libnspr4 4.8.7-0ubuntu3
   libnss3 3.12.9+ckbi-1.82-0ubuntu4
   libnss3-1d 3.12.9+ckbi-1.82-0ubuntu4
   libselinux1 2.0.98-1.1
   libsqlite3-0 3.7.7-2ubuntu1
   libssl1.0.0 1.0.0d-2ubuntu2
   libstdc++6 4.6.1-9ubuntu2
   libtasn1-3 2.9-4
   multiarch-support 2.13-17ubuntu2
   openjdk-6-jre-headless 6b23~pre8-1ubuntu1
   openjdk-6-jre-lib 6b23~pre8-1ubuntu1
   openssl 1.0.0d-2ubuntu2
   perl-base 5.12.4-4
   tzdata 2011g-0ubuntu0.11.04
   tzdata-java 2011g-0ubuntu0.11.04
   xz-utils 5.0.0-2
   zlib1g 1:1.2.3.4.dfsg-3ubuntu3
  DistroRelease: Ubuntu 11.10
  Package: openjdk-6-jre-headless 6b23~pre8-1ubuntu1
  PackageArchitecture: armel
  ProcEnviron:
   LANGUAGE=en_GB:
   LANG=en_GB.UTF-8
   SHELL=/bin/bash
  ProcVersionSignature: Ubuntu 3.0.0-1204.9-omap4 3.0.3
  SourcePackage: openjdk-6
  Uname: Linux 3.0.0-1204-omap4 armv7l
  UpgradeStatus: No upgrade log present (probably fresh install)

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