I upgraded a Debian Squeeze server to Wheezy recently which was running iSCSI with a Windows 7 initiator. When I started writing to the iSCSI device it would drop out and the server would show an oops message on screen like this:
iscsi_trgt: BUG at /var/lib/dkms/iscsitarget/1.4.20.2/build/kernel/iscsi.c:392 assert(req->tio)
In /var/log/messages the following was also logged:
Oct 30 22:17:36 server kernel: [ 916.894697] Pid: 6955, comm: istiod2 Tainted: G O 3.2.0-4-amd64 #1 Debian 3.2.51-1 Oct 30 22:17:36 server kernel: [ 916.894699] Call Trace: Oct 30 22:17:36 server kernel: [ 916.894709] [] ? send_data_rsp+0x45/0x1f4 [iscsi_trgt] Oct 30 22:17:36 server kernel: [ 916.894720] [ ] ? ua_pending+0x19/0xa5 [iscsi_trgt] Oct 30 22:17:36 server kernel: [ 916.894723] [ ] ? disk_execute_cmnd+0x1cf/0x22d [iscsi_trgt] Oct 30 22:17:36 server kernel: [ 916.894727] [ ] ? worker_thread+0xfd/0x255 [iscsi_trgt] Oct 30 22:17:36 server kernel: [ 916.894731] [ ] ? try_to_wake_up+0x197/0x197 Oct 30 22:17:36 server kernel: [ 916.894734] [ ] ? nthread_stop+0x35/0x35 [iscsi_trgt] Oct 30 22:17:36 server kernel: [ 916.894738] [ ] ? kthread+0x76/0x7e Oct 30 22:17:36 server kernel: [ 916.894742] [ ] ? kernel_thread_helper+0x4/0x10 Oct 30 22:17:36 server kernel: [ 916.894744] [ ] ? kthread_worker_fn+0x139/0x139 Oct 30 22:17:36 server kernel: [ 916.894747] [ ] ? gs_change+0x13/0x13 Oct 30 22:17:36 server kernel: [ 916.895041] CPU 2 Oct 30 22:17:36 server kernel: [ 916.895080] Modules linked in: iscsi_trgt(O) crc32c tun act_police sch_ingress cls_u32 sch_sfq sch_cbq xt_mark ipt_MASQUERADE xt_state xt_TCPMSS xt_tcpmss xt_tcpudp iptable_mangle iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack iptable_filter ip_tables x_tables fuse nfsd nfs nfs_acl auth_rpcgss fscache lockd sunrpc 8021q garp stp xfs loop processor iTCO_wdt radeon ttm i5100_edac drm_kms_helper drm power_supply i2c_algo_bit i2c_core edac_core iTCO_vendor_support thermal_sys joydev snd_pcm dcdbas button coretemp snd_page_alloc snd_timer snd soundcore psmouse pcspkr serio_raw evdev ext3 mbcache jbd dm_mod sr_mod sg cdrom sd_mod ses usbhid hid crc_t10dif enclosure ata_generic uhci_hcd ata_piix megaraid_sas mptsas ehci_hcd scsi_transport_sas mptscsih mptbase libata usbcore scsi_mod usb_common tg3 libphy [last unloaded: crc32c] Oct 30 22:17:36 server kernel: [ 916.897661] Oct 30 22:17:36 server kernel: [ 916.897698] Pid: 6955, comm: istiod2 Tainted: G O 3.2.0-4-amd64 #1 Debian 3.2.51-1 Dell Inc. PowerEdge R300/AAAAA Oct 30 22:17:36 server kernel: [ 916.897900] RIP: 0010:[ ] [ ] send_data_rsp+0x45/0x1f4 [iscsi_trgt] Oct 30 22:17:36 server kernel: [ 916.898055] RSP: 0018:ffff880203917e10 EFLAGS: 00010286 Oct 30 22:17:36 server kernel: [ 916.898138] RAX: 0000000000000000 RBX: ffff880224f85198 RCX: 0000000000003bbc Oct 30 22:17:36 server kernel: [ 916.898241] RDX: 0000000000003bbc RSI: ffff880203917f58 RDI: ffff880203917f58 Oct 30 22:17:36 server kernel: [ 916.898343] RBP: 0000000000000000 R08: 0000000000000002 R09: 00000000fffffffe Oct 30 22:17:36 server kernel: [ 916.898446] R10: 0000000000000000 R11: 0000000000000002 R12: ffff8802252e6240 Oct 30 22:17:36 server kernel: [ 916.898549] R13: ffff880224e34000 R14: ffff8802038c38d8 R15: ffff8802038c38e8 Oct 30 22:17:36 server kernel: [ 916.898652] FS: 0000000000000000(0000) GS:ffff88022fd00000(0000) knlGS:0000000000000000 Oct 30 22:17:36 server kernel: [ 916.898774] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b Oct 30 22:17:36 server kernel: [ 916.898857] CR2: 00007f1616d101a8 CR3: 0000000225bf9000 CR4: 00000000000406e0 Oct 30 22:17:36 server kernel: [ 916.898960] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 Oct 30 22:17:36 server kernel: [ 916.899063] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Oct 30 22:17:36 server kernel: [ 916.899166] Process istiod2 (pid: 6955, threadinfo ffff880203916000, task ffff8802252e6240) Oct 30 22:17:36 server kernel: [ 916.899335] ffff880200000000 ffff880226d39610 0000000000013780 ffffffffa058b0df Oct 30 22:17:36 server kernel: [ 916.899495] ffff880203917fd8 ffff880224f85198 ffff8802252e6240 ffff8802252e6240 Oct 30 22:17:36 server kernel: [ 916.899657] ffff880224e34000 ffff8802038c38d8 ffff8802038c38e8 ffffffffa0589db4 Oct 30 22:17:36 server kernel: [ 916.899861] [ ] ? ua_pending+0x19/0xa5 [iscsi_trgt] Oct 30 22:17:36 server kernel: [ 916.899955] [ ] ? disk_execute_cmnd+0x1cf/0x22d [iscsi_trgt] Oct 30 22:17:36 server kernel: [ 916.900077] [ ] ? worker_thread+0xfd/0x255 [iscsi_trgt] Oct 30 22:17:36 server kernel: [ 916.900192] [ ] ? try_to_wake_up+0x197/0x197 Oct 30 22:17:36 server kernel: [ 916.900280] [ ] ? nthread_stop+0x35/0x35 [iscsi_trgt] Oct 30 22:17:36 server kernel: [ 916.900380] [ ] ? kthread+0x76/0x7e Oct 30 22:17:36 server kernel: [ 916.900454] [ ] ? kernel_thread_helper+0x4/0x10 Oct 30 22:17:36 server kernel: [ 916.900555] [ ] ? kthread_worker_fn+0x139/0x139 Oct 30 22:17:36 server kernel: [ 916.900651] [ ] ? gs_change+0x13/0x13 Oct 30 22:17:36 server kernel: [ 916.901832] RSP Oct 30 22:17:36 server kernel: [ 916.901895] ---[ end trace cf3c9d794721a277 ]--- Oct 30 22:17:45 server kernel: [ 926.209749] iscsi_trgt: Logical Unit Reset (05) issued on tid:2 lun:1 by sid:562950876233792 (Function Complete) Oct 30 22:18:48 server kernel: [ 988.537909] PGD 225408067 PUD 223a53067 PMD 0
It appears to have been fixed in the latest iSCSI version but that has not made it to Debian packages yet (unless you run experimental). To upgrade do the following:
Check out the latest iSCSI code: svn co https://svn.code.sf.net/p/iscsitarget/code/
Make and install the code: cd code/trunk; make; make install
Restart iscsitarget on the server and the problem should then be fixed.