Nicholas, We patched this in and for the first time in many reboots, we didn't have iSCSI going straight into D state. We have had to work on a couple of other things, so we don't know if this is just a coincidence or not. We will reboot back into the old kernel and back a few times and do some more testing, but so far it has given us a little bit of hope that we may be narrowing down on the root cause. We will report back once we have some more info. Thank you, Robert LeBlanc ---------------- Robert LeBlanc PGP Fingerprint 79A2 9CA4 6CC4 45DD A904 C70E E654 3BB2 FA62 B9F1 On Tue, Oct 18, 2016 at 1:05 AM, Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx> wrote: > Hello Robert, Zhu & Co, > > Thanks for your detailed bug report. Comments inline below. > > On Mon, 2016-10-17 at 22:42 -0600, Robert LeBlanc wrote: >> Sorry I forget that Android has an aversion to plain text emails. >> >> If we can provide any information to help, let us know. We are willing >> to patch in more debug statements or whatever you think might help. >> Today has been a difficult day. Thanks for looking into it, I tried >> looking at it, but it is way over my head. >> >> ---------------- >> Robert LeBlanc >> PGP Fingerprint 79A2 9CA4 6CC4 45DD A904 C70E E654 3BB2 FA62 B9F1 >> >> >> On Mon, Oct 17, 2016 at 9:06 PM, Zhu Lingshan <lszhu@xxxxxxxx> wrote: >> > Hi Robert, >> > >> > I think the reason why you can not logout the targets is that iscsi_np in D >> > status. I think the patches fixed something, but it seems to be more than >> > one code path can trigger these similar issues. as you can see, there are >> > several call stacks, I am still working on it. Actually in my environment I >> > see there is another call stack not listed in your mail.... >> > >> > Thanks, >> > BR >> > Zhu Lingshan >> > >> > >> > On 10/18/2016 03:11 AM, Robert LeBlanc wrote: >> >> >> >> Sorry hit send too soon. >> >> >> >> In addition, on the client we see: >> >> # ps -aux | grep D | grep kworker >> >> root 5583 0.0 0.0 0 0 ? D 11:55 0:03 >> >> [kworker/11:0] >> >> root 7721 0.1 0.0 0 0 ? D 12:00 0:04 >> >> [kworker/4:25] >> >> root 10877 0.0 0.0 0 0 ? D 09:27 0:00 >> >> [kworker/22:1] >> >> root 11246 0.0 0.0 0 0 ? D 10:28 0:00 >> >> [kworker/30:2] >> >> root 14034 0.0 0.0 0 0 ? D 12:20 0:02 >> >> [kworker/19:15] >> >> root 14048 0.0 0.0 0 0 ? D 12:20 0:00 >> >> [kworker/16:0] >> >> root 15871 0.0 0.0 0 0 ? D 12:25 0:00 >> >> [kworker/13:0] >> >> root 17442 0.0 0.0 0 0 ? D 12:28 0:00 >> >> [kworker/9:1] >> >> root 17816 0.0 0.0 0 0 ? D 12:30 0:00 >> >> [kworker/11:1] >> >> root 18744 0.0 0.0 0 0 ? D 12:32 0:00 >> >> [kworker/10:2] >> >> root 19060 0.0 0.0 0 0 ? D 12:32 0:00 >> >> [kworker/29:0] >> >> root 21748 0.0 0.0 0 0 ? D 12:40 0:00 >> >> [kworker/21:0] >> >> root 21967 0.0 0.0 0 0 ? D 12:40 0:00 >> >> [kworker/22:0] >> >> root 21978 0.0 0.0 0 0 ? D 12:40 0:00 >> >> [kworker/22:2] >> >> root 22024 0.0 0.0 0 0 ? D 12:40 0:00 >> >> [kworker/22:4] >> >> root 22035 0.0 0.0 0 0 ? D 12:40 0:00 >> >> [kworker/22:5] >> >> root 22060 0.0 0.0 0 0 ? D 12:40 0:00 >> >> [kworker/16:1] >> >> root 22282 0.0 0.0 0 0 ? D 12:41 0:00 >> >> [kworker/26:0] >> >> root 22362 0.0 0.0 0 0 ? D 12:42 0:00 >> >> [kworker/18:9] >> >> root 22426 0.0 0.0 0 0 ? D 12:42 0:00 >> >> [kworker/16:3] >> >> root 23298 0.0 0.0 0 0 ? D 12:43 0:00 >> >> [kworker/12:1] >> >> root 23302 0.0 0.0 0 0 ? D 12:43 0:00 >> >> [kworker/12:5] >> >> root 24264 0.0 0.0 0 0 ? D 12:46 0:00 >> >> [kworker/30:1] >> >> root 24271 0.0 0.0 0 0 ? D 12:46 0:00 >> >> [kworker/14:8] >> >> root 24441 0.0 0.0 0 0 ? D 12:47 0:00 >> >> [kworker/9:7] >> >> root 24443 0.0 0.0 0 0 ? D 12:47 0:00 >> >> [kworker/9:9] >> >> root 25005 0.0 0.0 0 0 ? D 12:48 0:00 >> >> [kworker/30:3] >> >> root 25158 0.0 0.0 0 0 ? D 12:49 0:00 >> >> [kworker/9:12] >> >> root 26382 0.0 0.0 0 0 ? D 12:52 0:00 >> >> [kworker/13:2] >> >> root 26453 0.0 0.0 0 0 ? D 12:52 0:00 >> >> [kworker/21:2] >> >> root 26724 0.0 0.0 0 0 ? D 12:53 0:00 >> >> [kworker/19:1] >> >> root 28400 0.0 0.0 0 0 ? D 05:20 0:00 >> >> [kworker/25:1] >> >> root 29552 0.0 0.0 0 0 ? D 11:40 0:00 >> >> [kworker/17:1] >> >> root 29811 0.0 0.0 0 0 ? D 11:40 0:00 >> >> [kworker/7:10] >> >> root 31903 0.0 0.0 0 0 ? D 11:43 0:00 >> >> [kworker/26:1] >> >> >> >> And all of the processes have this stack: >> >> [<ffffffffa0727ed5>] iser_release_work+0x25/0x60 [ib_iser] >> >> [<ffffffff8109633f>] process_one_work+0x14f/0x400 >> >> [<ffffffff81096bb4>] worker_thread+0x114/0x470 >> >> [<ffffffff8109c6f8>] kthread+0xd8/0xf0 >> >> [<ffffffff8172004f>] ret_from_fork+0x3f/0x70 >> >> [<ffffffffffffffff>] 0xffffffffffffffff >> >> >> >> We are not able to log out of the sessions in all cases. And have to >> >> restart the box. >> >> >> >> iscsiadm -m session will show messages like: >> >> iscsiadm: could not read session targetname: 5 >> >> iscsiadm: could not find session info for session100 >> >> iscsiadm: could not read session targetname: 5 >> >> iscsiadm: could not find session info for session101 >> >> iscsiadm: could not read session targetname: 5 >> >> iscsiadm: could not find session info for session103 >> >> ... >> >> >> >> I can't find any way to force iscsiadm to clean up these sessions >> >> possibly due to tasks in D state. >> >> ---------------- >> >> Robert LeBlanc >> >> PGP Fingerprint 79A2 9CA4 6CC4 45DD A904 C70E E654 3BB2 FA62 B9F1 >> >> >> >> >> >> On Mon, Oct 17, 2016 at 10:32 AM, Robert LeBlanc <robert@xxxxxxxxxxxxx> >> >> wrote: >> >>> >> >>> Some more info as we hit this this morning. We have volumes mirrored >> >>> between two targets and we had one target on the kernel with the three >> >>> patches mentioned in this thread [0][1][2] and the other was on a >> >>> kernel without the patches. We decided that after a week and a half we >> >>> wanted to get both targets on the same kernel so we rebooted the >> >>> non-patched target. Within an hour we saw iSCSI in D state with the >> >>> same stack trace so it seems that we are not hitting any of the >> >>> WARN_ON lines. We are getting both iscsi_trx and iscsi_np both in D >> >>> state, this time we have two iscsi_trx processes in D state. I don't >> >>> know if stale sessions on the clients could be contributing to this >> >>> issue (the target trying to close non-existent sessions??). This is on >> >>> 4.4.23. Any more debug info we can throw at this problem to help? >> >>> >> >>> Thank you, >> >>> Robert LeBlanc >> >>> >> >>> # ps aux | grep D | grep iscsi >> >>> root 16525 0.0 0.0 0 0 ? D 08:50 0:00 >> >>> [iscsi_np] >> >>> root 16614 0.0 0.0 0 0 ? D 08:50 0:00 >> >>> [iscsi_trx] >> >>> root 16674 0.0 0.0 0 0 ? D 08:50 0:00 >> >>> [iscsi_trx] >> >>> >> >>> # for i in 16525 16614 16674; do echo $i; cat /proc/$i/stack; done >> >>> 16525 >> >>> [<ffffffff814f0d5f>] iscsit_stop_session+0x19f/0x1d0 >> >>> [<ffffffff814e2516>] iscsi_check_for_session_reinstatement+0x1e6/0x270 >> >>> [<ffffffff814e4ed0>] iscsi_target_check_for_existing_instances+0x30/0x40 >> >>> [<ffffffff814e5020>] iscsi_target_do_login+0x140/0x640 >> >>> [<ffffffff814e63bc>] iscsi_target_start_negotiation+0x1c/0xb0 >> >>> [<ffffffff814e410b>] iscsi_target_login_thread+0xa9b/0xfc0 >> >>> [<ffffffff8109c748>] kthread+0xd8/0xf0 >> >>> [<ffffffff8172018f>] ret_from_fork+0x3f/0x70 >> >>> [<ffffffffffffffff>] 0xffffffffffffffff >> >>> 16614 >> >>> [<ffffffff814cca79>] target_wait_for_sess_cmds+0x49/0x1a0 >> >>> [<ffffffffa064692b>] isert_wait_conn+0x1ab/0x2f0 [ib_isert] >> >>> [<ffffffff814f0ef2>] iscsit_close_connection+0x162/0x870 >> >>> [<ffffffff814df9bf>] iscsit_take_action_for_connection_exit+0x7f/0x100 >> >>> [<ffffffff814f00a0>] iscsi_target_rx_thread+0x5a0/0xe80 >> >>> [<ffffffff8109c748>] kthread+0xd8/0xf0 >> >>> [<ffffffff8172018f>] ret_from_fork+0x3f/0x70 >> >>> [<ffffffffffffffff>] 0xffffffffffffffff >> >>> 16674 >> >>> [<ffffffff814cca79>] target_wait_for_sess_cmds+0x49/0x1a0 >> >>> [<ffffffffa064692b>] isert_wait_conn+0x1ab/0x2f0 [ib_isert] >> >>> [<ffffffff814f0ef2>] iscsit_close_connection+0x162/0x870 >> >>> [<ffffffff814df9bf>] iscsit_take_action_for_connection_exit+0x7f/0x100 >> >>> [<ffffffff814f00a0>] iscsi_target_rx_thread+0x5a0/0xe80 >> >>> [<ffffffff8109c748>] kthread+0xd8/0xf0 >> >>> [<ffffffff8172018f>] ret_from_fork+0x3f/0x70 >> >>> [<ffffffffffffffff>] 0xffffffffffffffff >> >>> >> >>> >> >>> [0] https://www.spinics.net/lists/target-devel/msg13463.html >> >>> [1] http://marc.info/?l=linux-scsi&m=147282568910535&w=2 >> >>> [2] http://www.spinics.net/lists/linux-scsi/msg100221.html > > The call chain above is iscsi session reinstatement driven by > open-iscsi/iser resulting in target-core to sleep indefinitely, waiting > for outstanding target-core backend driver se_cmd I/O to complete in > order to make forward progress. > > Note, there is a v4.1+ se_cmd->cmd_kref reference leak bug for > TMR ABORT_TASK during simultaneous target back-end I/O completion > timeouts here: > > http://www.spinics.net/lists/target-devel/msg13530.html > > If you are actively observing TMR ABORT_TASK preceding the hung task > timeout warnings above with v4.4.y + v4.2.y iser-target exports, then > it's likely the same bug. Please apply the patch on your v4.x setup to > verify. > > If no TMR ABORT_TASK timeouts + session reinstatements are occurring on > your iser-target setup, then it is a separate bug. > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
