The reason why this bug happens are that some process, currently unknown to us which one, have locked and keeps on holding the kernel &mm->mmap_sem lock without releasing it.
When java hits a pagefault then the Linux kernel needs to aquire this lock in order to serve the pagefault, it waits, and wait for this lock to become available again, unfortunally in this case the kernel waits forever... note that this bug also prevents other tools from operating like ps ax http://www.kernel.org/doc/Documentation/vm/locking -- You received this bug notification because you are a member of OpenJDK, which is subscribed to openjdk-6 in Ubuntu. 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) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openjdk-6/+bug/845158/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~openjdk Post to : [email protected] Unsubscribe : https://launchpad.net/~openjdk More help : https://help.launchpad.net/ListHelp
