I have an active/active drbd cluster with pacemaker running on cman. If I create a file on the shared gfs2 file system on one node, then try to delete it on the other, I'm receiving this kernel panic. I get the same error on both nodes, so it's not specific to either machine.
Jul 2 12:54:37 ha1 lrmd: [40983]: info: operation monitor[35] on nova-volumes:0 for client 40986: pid 2385 exited with return code 0
Jul 2 12:54:43 ha1 lrmd: [40983]: debug: rsc:p_gfsd:1 monitor[63] (pid 2459)
Jul 2 12:54:43 ha1 lrmd: [40983]: info: operation monitor[63] on p_gfsd:1 for client 40986: pid 2459 exited with return code 0
Jul 2 12:54:49 ha1 kernel: [238066.234067] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
Jul 2 12:54:49 ha1 kernel: [238066.236034] IP: [<ffffffffa037c00a>] gfs2_unlink+0x8a/0x220 [gfs2]
Jul 2 12:54:49 ha1 kernel: [238066.237305] PGD 40ca9f067 PUD 40de7b067 PMD 0
Jul 2 12:54:49 ha1 kernel: [238066.237336] Oops: 0000 [#1] SMP
Jul 2 12:54:49 ha1 kernel: [238066.237336] CPU 7
Jul 2 12:54:49 ha1 kernel: [238066.237336] Modules linked in: gfs2 drbd lru_cache ipmi_si mpt2sas scsi_transport_sas raid_class mptctl mptbase ipmi_devintf ipmi_msghandler dell_rbu kvm_amd kvm dlm configfs vesafb ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad ib_core ib_addr iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi ext2 bonding psmouse sp5100_tco dcdbas tpm_tis joydev serio_raw i2c_piix4 amd64_edac_mod k10temp edac_core acpi_power_meter edac_mce_amd mac_hid lp parport usbhid hid ses enclosure igb megaraid_sas dca bnx2 [last unloaded: ipmi_si]
Jul 2 12:54:49 ha1 kernel: [238066.237336]
Jul 2 12:54:49 ha1 kernel: [238066.237336] Pid: 2544, comm: rm Not tainted 3.2.0-26-generic #41-Ubuntu Dell Inc. PowerEdge R515/03X0MN
Jul 2 12:54:49 ha1 kernel: [238066.237336] RIP: 0010:[<ffffffffa037c00a>] [<ffffffffa037c00a>] gfs2_unlink+0x8a/0x220 [gfs2]
Jul 2 12:54:49 ha1 kernel: [238066.237336] RSP: 0018:ffff8801fe13fd28 EFLAGS: 00010296
Jul 2 12:54:49 ha1 kernel: [238066.380032] RAX: 0000000000000000 RBX: ffff880410faa080 RCX: ffff8801fe13fd40
Jul 2 12:54:49 ha1 kernel: [238066.380032] RDX: 0000000000000000 RSI: 0000000000012346 RDI: ffff88040c8b1440
Jul 2 12:54:49 ha1 kernel: [238066.380032] RBP: ffff8801fe13fe38 R08: 4000000000000000 R09: 0000000000000000
Jul 2 12:54:49 ha1 kernel: [238066.380032] R10: fde3ec81bcd7720a R11: 0000000000000008 R12: ffff8801ffc709c0
Jul 2 12:54:49 ha1 kernel: [238066.380032] R13: ffff8801fe13fd80 R14: ffff8803f479d140 R15: ffff88040c8b1000
Jul 2 12:54:49 ha1 kernel: [238066.380032] FS: 00007fa1b5055700(0000) GS:ffff88041fa20000(0000) knlGS:0000000000000000
Jul 2 12:54:49 ha1 kernel: [238066.380032] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jul 2 12:54:49 ha1 kernel: [238066.380032] CR2: 0000000000000018 CR3: 00000003f207c000 CR4: 00000000000006e0
Jul 2 12:54:49 ha1 kernel: [238066.380032] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Jul 2 12:54:49 ha1 kernel: [238066.380032] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Jul 2 12:54:49 ha1 kernel: [238066.380032] Process rm (pid: 2544, threadinfo ffff8801fe13e000, task ffff8802044b5bc0)
Jul 2 12:54:49 ha1 kernel: [238066.380032] Stack:
Jul 2 12:54:49 ha1 kernel: [238066.380032] 0000000000000003 ffff8801fa72e260 ffff8801fe13fd58 ffff8801fe13fd40
Jul 2 12:54:49 ha1 kernel: [238066.380032] ffff8801fe13fd40 ffff8801fa72e218 ffff88020476a680 0000000000000001
Jul 2 12:54:49 ha1 kernel: [238066.380032] 0000000000000000 0000000000000000 ffffffffa037bfda ffff8801fe13fd80
Jul 2 12:54:49 ha1 kernel: [238066.380032] Call Trace:
Jul 2 12:54:49 ha1 kernel: [238066.380032] [<ffffffffa037bfda>] ? gfs2_unlink+0x5a/0x220 [gfs2]
Jul 2 12:54:49 ha1 kernel: [238066.380032] [<ffffffffa037bff4>] ? gfs2_unlink+0x74/0x220 [gfs2]
Jul 2 12:54:49 ha1 kernel: [238066.380032] [<ffffffff8129cb2c>] ? security_inode_permission+0x1c/0x30
Jul 2 12:54:49 ha1 kernel: [238066.380032] [<ffffffff81184e70>] vfs_unlink.part.26+0x80/0xf0
Jul 2 12:54:49 ha1 kernel: [238066.380032] [<ffffffff81184f1c>] vfs_unlink+0x3c/0x60
Jul 2 12:54:49 ha1 kernel: [238066.380032] [<ffffffff8118758a>] do_unlinkat+0x1aa/0x1d0
Jul 2 12:54:49 ha1 kernel: [238066.380032] [<ffffffff8117ce5a>] ? sys_newfstatat+0x2a/0x40
Jul 2 12:54:49 ha1 kernel: [238066.380032] [<ffffffff811880d2>] sys_unlinkat+0x22/0x40
Jul 2 12:54:49 ha1 kernel: [238066.380032] [<ffffffff81661fc2>] system_call_fastpath+0x16/0x1b
Jul 2 12:54:49 ha1 kernel: [238066.380032] Code: 00 00 49 83 c5 40 31 d2 4c 89 e9 be 01 00 00 00 e8 fc 1e ff ff 48 8b b3 28 02 00 00 4c 89 ff e8 ad 7e 00 00 48 8d 8d 08 ff ff ff <48> 8b 78 18 31 d2 be 01 00 00 00 48 83 e9 80 e8 d2 1e ff ff 48
Jul 2 12:54:49 ha1 kernel: [238066.380032] RIP [<ffffffffa037c00a>] gfs2_unlink+0x8a/0x220 [gfs2]
Jul 2 12:54:49 ha1 kernel: [238066.380032] RSP <ffff8801fe13fd28>
Jul 2 12:54:49 ha1 kernel: [238066.380032] CR2: 0000000000000018
Jul 2 12:54:49 ha1 kernel: [238066.394510] ---[ end trace 2009fc896a3dd969 ]---
I found this in a blog posting found here: http:// blog.init. hr/?p=186.
Important: We’ve encountered couple of bugs that are in the queue for fixing. If you are using or have a desire of using cLVM, please do not use 12.04 yet. Once these fixes land into archives, we’ll send an email to ubuntu-ha mailing list and add cLVM howto to the wiki.
Is this one of the bugs that was referred to there?