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Date: Wed, 26 Jun 2013 17:38:35 +0900 From: Akira Fujita <a-fujita@...jp.nec.com> To: Jan Kara <jack@...e.cz> CC: Dmitry Monakhov <dmonakhov@...nvz.org>, ext4 development <linux-ext4@...r.kernel.org> Subject: Re: [BUG] xfstest269 causes deadlock on linux-3.9.0 (ext4) (2013/06/25 20:27), Jan Kara wrote: > On Tue 25-06-13 19:06:53, Akira Fujita wrote: >> >> >> (2013/06/24 20:04), Jan Kara wrote: >>> On Tue 28-05-13 17:36:09, Akira Fujita wrote: >>>> Hello, >>>> >>>> (2013/05/27 17:33), Jan Kara wrote: >>>>> On Mon 27-05-13 12:16:01, Dmitry Monakhov wrote: >>>>>> On Mon, 27 May 2013 10:49:11 +0900, Akira Fujita <a-fujita@...jp.nec.com> wrote: >>>>>>> Hi Jan, >>>>>>> >>>>>>> (2013/05/15 11:57), Akira Fujita wrote: >>>>>>>> Hi, >>>>>>>> >>>>>>>> (2013/05/15 6:37), Jan Kara wrote: >>>>>>>>> Hello, >>>>>>>>> >>>>>>>>> On Mon 13-05-13 15:49:24, Akira Fujita wrote: >>>>>>>>>> I ran into the deaclock with xfs_test 269 on linux-3.9.0. >>>>>>>>>> It seems happen between jbd2_log_wait_commit, sleep_on_buffer >>>>>>>>>> and writeback_indoes (Please see ps log below). >>>>>>>>>> Once it occurs we can't touch FS anymore. >>>>>>>>>> In my case 300 - 1000 trials to occur. Is this known issue? >>>>>>>>>> >>>>>>>>>> The following kernels seems to have same problem: >>>>>>>>>> - linux-3.5-rc5 >>>>>>>>>> - linux-3.8.5 >>>>>>>>>> - linux-3.9-rc7 >>>>>>>>>> And now I'm trying it on linux-3.10-rc1. >>>>>>>>>> >>>>>>>>>> # ./check generic/269 >>>>>>>>>> FSTYP -- ext4 >>>>>>>>>> PLATFORM -- Linux/x86_64 mcds1 3.9.0 >>>>>>>>>> MKFS_OPTIONS -- /dev/sda12 >>>>>>>>>> MOUNT_OPTIONS -- -o acl,user_xattr /dev/sda12 /mnt/mp2 >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> # ps -eo pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:16,comm >>>>>>>>>> PID TID CLS RTPRIO NI PRI PSR %CPU STAT WCHAN COMMAND >>>>>>>>>> 1 1 TS - 0 19 0 0.0 Ss poll_schedule_ti init >>>>>>>>>> 2 2 TS - 0 19 0 0.0 S kthreadd kthreadd >>>>>>>>>> 3 3 TS - 0 19 0 0.0 S smpboot_thread_f ksoftirqd/0 >>>>>>>>>> ... >>>>>>>>>> 2391 2391 TS - 0 19 2 0.1 D jbd2_log_wait_co flush-8:0 >>>>>>>>>> ... >>>>>>>>>> 22647 22647 TS - 0 19 3 0.0 S worker_thread kworker/3:1 >>>>>>>>>> 22655 22655 TS - 0 19 0 0.0 S hrtimer_nanoslee sleep >>>>>>>>>> 22657 22657 TS - 0 19 2 0.0 R+ - ps >>>>>>>>>> 25330 25330 TS - 0 19 0 0.0 S worker_thread kworker/0:0 >>>>>>>>>> 28963 28963 TS - 0 19 1 0.0 S+ wait loop_xfstests.s >>>>>>>>>> 28964 28964 TS - 0 19 1 0.0 S+ wait check >>>>>>>>>> 29180 29180 TS - 0 19 3 0.0 S kjournald2 jbd2/sda11-8 >>>>>>>>>> 29181 29181 TS - -20 39 3 0.0 S< rescuer_thread ext4-dio-unwrit >>>>>>>>>> 29199 29199 TS - 0 19 3 0.0 S+ wait 269 >>>>>>>>>> 29391 29391 TS - 0 19 0 0.6 D sleep_on_buffer jbd2/sda12-8 >>>>>>>>>> 29392 29392 TS - -20 39 3 0.0 S< rescuer_thread ext4-dio-unwrit >>>>>>>>>> 29394 29394 TS - 0 19 0 0.0 S wait fsstress >>>>>>>>>> 29505 29505 TS - 0 19 3 0.0 D writeback_inodes fsstress >>>>>>>>>> >>>>>>>>>> # df -T /dev/sda11 /dev/sda12 >>>>>>>>>> Filesystem Type 1K-blocks Used Available Use% Mounted on >>>>>>>>>> /dev/sda11 ext4 9857264 22308 9327564 1% /mnt/mp1 >>>>>>>>>> /dev/sda12 ext4 499656 499656 0 100% /mnt/mp2 >>>>>>>>> Thanks for report. No I don't think this problem has been reported >>>>>>>>> before. Seeing that sda12 is out of space and fsstress hangs in >>>>>>>>> writeback_inodes(), I suspect we have some deadlock in ENOSPC recovery path >>>>>>>>> when we want to flush data to disk to reduce delalloc uncertainty. Can you >>>>>>>>> run 'echo w >/proc/sysrq-trigger' when the deadlock happens and post your >>>>>>>>> dmesg here? Thanks! >>>>>>>>> >>>>>>>> >>>>>>>> Thanks for reply. >>>>>>>> I'll take that information when the deadlock happens again. >>>>>>> >>>>>>> Finally, I got the following messages on linux-3.9.0. >>>>>>> Could you take a look? >>>>>> Is it a real deadlock? >>>>>> umount wait for flush-8:0 >>>>>> flush wait for jbd2 >>>>>> jbd2 wait for bh. >>>>>> All buffer-heads will be written at sooner or later. >>>>>> It probably will require significant amount of time, because fs is too >>>>>> fragmented(that is what this test all about), but it is not a deadlock. >>>>> Yeah, that is my analysis as well. I was only thinking whether we >>>>> couldn't forget some buffer locked on some error recovery path (we are >>>>> getting ENOSPC) but it's not obvious where it would be. Akira-san, could >>>>> you also send us disassembly of your jbd2_journal_commit_transaction() >>>>> function so that we can check where exactly offset 0xee0 is in the >>>>> function? >>>>> >>>>> Honza >>>> >>>> I attached disasemble code of jbd2_journal_commit_tnrasaction, >>>> please check it. >>> Thanks. I've looked into the disassembly now and we are waiting for the >>> write of commit record to finish. We have submitted the buffer just before >>> so it can hardly be some issue like forgotten locked buffer. Really >>> strange. It looks like some problem in block layer, device driver, or HW >>> itself... I'm thinking how to debug this further - it would be good if we >>> had blktrace data just before the moment when the hang happens but given >>> how hard this is to reproduce the traces would be extremly large... >>> >>> One idea - can you try whether the problem reproduces with 'nobarrier' >>> mount option? It could be some problem with flush / fua handling. >>> >> >> OK, I'll try to reproduce this issue with 'nobarrier' >> (and take blktrace log if I can). > You can restart the blktrace every 5 minutes or so, so that trace files > don't get too big. If we have a trace for a minute before the machine crashes > it should be enough for debugging. Thanks for advice, I'll try it. In my environment, 1 time xfstests269 running generates about 150MB log by blktrace, so taking log seems okay. Thanks, Akira Fujita -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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