I think this is the issue.. http://tracker.ceph.com/issues/9073 Thanks & Regards Somnath From: Somnath Roy Sent: Tuesday, August 19, 2014 6:25 PM To: Sage Weil (sage at inktank.com); Samuel Just (sam.just at inktank.com) Cc: ceph-users at lists.ceph.com Subject: Deadlock in ceph journal Hi Sage/Sam, During our testing we found a potential deadlock scenario in the filestore journal code base. This is happening because of two reason. 1. This is because code is not signaling aio_cond from check_aio_completion() in case seq = 0 2. Following changes in the write_thread_entry() is allowing a very first header write with seq = 0. if (writeq.empty() && !must_write_header) { Now, during ceph-deploy activate this is what happening. 1. The very first write of header with seq = 0 issued and it is waiting for aio completion. So, aio_num = 1. 2. superblock write came in and got into while (aio_num > 0) block of write_thread_entry() and waiting on the aio_cond 3. The seq = 0 aio completed but not setting completed_something = true and as a result aio_cond is not signaled. 4. write_thread_entry() is getting into deadlock. This is a timing problem and if header write is returned before superblock write this will not happen and will be happening in case of block journal device only (aio is enabled). Here is the log snippet we are getting. 2014-08-19 12:59:10.029363 7f60fa33b700 10 journal write_thread_entry start 2014-08-19 12:59:10.029395 7f60fa33b700 20 journal prepare_multi_write queue_pos now 4096 2014-08-19 12:59:10.029427 7f60fa33b700 15 journal do_aio_write writing 4096~0 + header 2014-08-19 12:59:10.029439 7f60fa33b700 20 journal write_aio_bl 0~4096 seq 0 2014-08-19 12:59:10.029442 7f60f9339700 10 journal write_finish_thread_entry enter 2014-08-19 12:59:10.029466 7f60fa33b700 20 journal write_aio_bl .. 0~4096 in 1 2014-08-19 12:59:10.029498 7f60fa33b700 20 journal write_aio_bl 4096~0 seq 0 2014-08-19 12:59:10.029505 7f60fa33b700 5 journal put_throttle finished 0 ops and 0 bytes, now 0 ops and 0 bytes 2014-08-19 12:59:10.029510 7f60fa33b700 20 journal write_thread_entry going to sleep 2014-08-19 12:59:10.029538 7f60ff178800 10 journal journal_start 2014-08-19 12:59:10.029566 7f60f9339700 20 journal write_finish_thread_entry waiting for aio(s) 2014-08-19 12:59:10.029726 7f60ff178800 15 filestore(/var/lib/ceph/tmp/mnt.NKfs2R) read meta/23c2fcde/osd_superblock/0//-1 0~0 2014-08-19 12:59:10.029793 7f60ff178800 -1 filestore(/var/lib/ceph/tmp/mnt.NKfs2R) could not find 23c2fcde/osd_superblock/0//-1 in index: (2) No such file or directory 2014-08-19 12:59:10.029815 7f60ff178800 10 filestore(/var/lib/ceph/tmp/mnt.NKfs2R) FileStore::read(meta/23c2fcde/osd_superblock/0//-1) open error: (2) No such file or directory 2014-08-19 12:59:10.029892 7f60ff178800 5 filestore(/var/lib/ceph/tmp/mnt.NKfs2R) queue_transactions new osr(default 0x42ea9f0)/0x42ea9f0 2014-08-19 12:59:10.029922 7f60ff178800 10 journal op_submit_start 2 2014-08-19 12:59:10.030009 7f60ff178800 5 filestore(/var/lib/ceph/tmp/mnt.NKfs2R) queue_transactions (writeahead) 2 0x7fff6e817080 2014-08-19 12:59:10.030028 7f60ff178800 10 journal op_journal_transactions 2 0x7fff6e817080 2014-08-19 12:59:10.030039 7f60ff178800 5 journal submit_entry seq 2 len 505 (0x42a76f0) 2014-08-19 12:59:10.030065 7f60fa33b700 20 journal write_thread_entry woke up 2014-08-19 12:59:10.030070 7f60fa33b700 20 journal write_thread_entry aio throttle: aio num 1 bytes 4096 ... exp 2 min_new 4 ... pending 0 2014-08-19 12:59:10.030076 7f60fa33b700 20 journal write_thread_entry deferring until more aios complete: 1 aios with 4096 bytes needs 4 bytes to start a new aio (currently 0 pending) 2014-08-19 12:59:10.030084 7f60ff178800 10 journal op_submit_finish 2 2014-08-19 12:59:10.030389 7f60f9339700 10 journal write_finish_thread_entry aio 0~4096 done 2014-08-19 12:59:10.030402 7f60f9339700 20 journal check_aio_completion 2014-08-19 12:59:10.030406 7f60f9339700 20 journal check_aio_completion completed seq 0 0~4096 2014-08-19 12:59:10.030412 7f60f9339700 20 journal write_finish_thread_entry sleeping 2014-08-19 12:59:15.026609 7f60fab3c700 20 filestore(/var/lib/ceph/tmp/mnt.NKfs2R) sync_entry woke after 5.000459 2014-08-19 12:59:15.026659 7f60fab3c700 10 journal commit_start max_applied_seq 1, open_ops 0 2014-08-19 12:59:15.026665 7f60fab3c700 10 journal commit_start blocked, all open_ops have completed 2014-08-19 12:59:15.026670 7f60fab3c700 10 journal commit_start nothing to do 2014-08-19 12:59:15.026676 7f60fab3c700 10 journal commit_start 2014-08-19 12:59:15.026691 7f60fab3c700 20 filestore(/var/lib/ceph/tmp/mnt.NKfs2R) sync_entry waiting for max_interval 5.000000 2014-08-19 12:59:20.026826 7f60fab3c700 20 filestore(/var/lib/ceph/tmp/mnt.NKfs2R) sync_entry woke after 5.000135 2014-08-19 12:59:20.026870 7f60fab3c700 10 journal commit_start max_applied_seq 1, open_ops 0 2014-08-19 12:59:20.026876 7f60fab3c700 10 journal commit_start blocked, all open_ops have completed 2014-08-19 12:59:20.026879 7f60fab3c700 10 journal commit_start nothing to do 2014-08-19 12:59:20.026891 7f60fab3c700 10 journal commit_start Could you please confirm this as a valid defect ? If so, sending a signal on aio_cond in case of seq = 0, could be the solution ? Please let me know if there is any potential workaround for this while deploying with ceph-deploy. Will ceph-deploy accept file path as journal ? Thanks & Regards Somnath ________________________________ PLEASE NOTE: The information contained in this electronic mail message is intended only for the use of the designated recipient(s) named above. If the reader of this message is not the intended recipient, you are hereby notified that you have received this message in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify the sender by telephone or e-mail (as shown above) immediately and destroy any and all copies of this message in your possession (whether hard copies or electronically stored copies). -------------- next part -------------- An HTML attachment was scrubbed... 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