Bart: After researching the problem you described below, I have determined that a kernel bug with dcache processing is the culprit, affecting OrangeFS as well as other filesystems. The bug is first introduced in RHEL 5.8, linux-2.6.18-308.1.1.el5.x86_64 and persists throughout the remaining 5.8 life cycle (linux-2.6.18-308.20.1.el5.x86_64). The initial release of 5.8, which uses linux-2.6.18-308.el5.x86_64 works correctly. The first release of RHEL 6.0, which uses linux-2.6.32-71.18.1, also works correctly.
I have tried to narrow down which vanilla linux version contains the correction to this problem and have determined that somewhere between 2.6.25 and 2.6.27 is where the fix occurred. I found bug reports about similar kernel panics surrounding slightly different scenarios where a fix was available in 2.6.25. In addition, I found where major dcache changes were made starting in 2.6.27. I haven't actually tried running these particular linux versions to verify, but the research seems sound. If you find out which vanilla linux version has the correction in it, please let us know. Thanks, Becky Ligon On Tue, Oct 30, 2012 at 5:41 PM, Bart Taylor <bat...@gmail.com> wrote: > > Has anyone else experienced consistent kernel panics on unmount? > > I frequently get a kernel panic when I unmount a file system from a RHEL5 > x86_64 client (kernel = 2.6.18-308.el5). That is the latest RHEL5 kernel. I > tested this against a stock Orangefs 2.8.6 build and also against older > PVFS 2.8 and PVFS 2.6 builds; a panic results in all cases. I also tried an > errata build kernel=2.6.18-308.8.1.el5. > > Here is my test case: > > Setup: > [root@client1 ~]# mkdir /mnt/orangefs/foo > [root@client1 ~]# echo "bar" > /mnt/orangefs/foo/bar > > Trigger a panic: > [root@client1 ~]# mount -t pvfs2 tcp://server2:3334/pvfs2-fs > /mnt/orangefs/ > [root@client1 ~]# cp /mnt/orangefs/foo/bar /mnt/orangefs/ > [root@client1 ~]# umount /mnt/orangefs/ > > > Below is the backtrace I get from the core file. The exception is always > in shrink_dcache_for_unmount via the pvfs2_kill_sb call. > > Bart. > > > > crash> bt > PID: 30232 TASK: ffff8101bbf220c0 CPU: 0 COMMAND: "umount" > #0 [ffff81019eb77b60] crash_kexec at ffffffff800b099c > #1 [ffff81019eb77c20] __die at ffffffff80065137 > #2 [ffff81019eb77c60] die at ffffffff8006c789 > #3 [ffff81019eb77c90] do_invalid_op at ffffffff8006cd49 > #4 [ffff81019eb77d50] error_exit at ffffffff8005dde9 > [exception RIP: shrink_dcache_for_umount_subtree+375] > RIP: ffffffff800ef567 RSP: ffff81019eb77e08 RFLAGS: 00010286 > RAX: 000000000000005d RBX: ffff8101a32029c0 RCX: ffffffff80323028 > RDX: ffffffff80323028 RSI: 0000000000000000 RDI: ffffffff80323020 > RBP: ffff81019eb4e9d0 R8: ffffffff80323028 R9: 000000000000003e > R10: ffff81019eb77aa8 R11: 0000000000000080 R12: ffff8101a3202a20 > R13: 0000000000000000 R14: 0000000000000000 R15: 00000000125aa580 > ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 > #5 [ffff81019eb77e30] shrink_dcache_for_umount at ffffffff800efa83 > #6 [ffff81019eb77e40] generic_shutdown_super at ffffffff800e774d > #7 [ffff81019eb77e60] kill_anon_super at ffffffff800e787b > #8 [ffff81019eb77e70] pvfs2_kill_sb at ffffffff88725b8a [pvfs2] > #9 [ffff81019eb77e90] deactivate_super at ffffffff800e792c > #10 [ffff81019eb77eb0] sys_umount at ffffffff800f1e8b > #11 [ffff81019eb77f80] system_call at ffffffff8005d116 > RIP: 00000036b80d4a67 RSP: 00007fffc15c4ee8 RFLAGS: 00010246 > RAX: 00000000000000a6 RBX: ffffffff8005d116 RCX: 0000000000406d3f > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000125ab490 > RBP: 00000000125ab4f0 R8: 0000000000000004 R9: 0000000000000001 > R10: 0000000000000008 R11: 0000000000000246 R12: 00000000125ab460 > R13: 00000000125ab490 R14: 00000000125ab4f0 R15: 0000000000000000 > ORIG_RAX: 00000000000000a6 CS: 0033 SS: 002b > > > _______________________________________________ > Pvfs2-developers mailing list > Pvfs2-developers@beowulf-underground.org > http://www.beowulf-underground.org/mailman/listinfo/pvfs2-developers > > -- Becky Ligon OrangeFS Support and Development Omnibond Systems Anderson, South Carolina
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