Re: FYI for aarch64 main [14] running a mid March version: I ended up with [usb{usbus2}] stuck at (near) 100% cpu

> 
> On 2021-May-14, at 05:52, Rodney W. Grimes <freebsd-rwg  at gndrsh.dnsmgr.net> wrote:
> 
> >> Note: The context was using a non-debug main build
> >>      from mid-2021-Mar. (More details identified
> >>      later.)
> >> 
> >> The issue happend while attempting a:
> >> 
> >> # zfs send -R zpold@for-copy | zfs recv -Fdv zpnew
> >> 
> >> where the drives involved in the command were:
> >> 
> >> zpold: a USB3 SSD, using /dev/da0p3
> >> zpnew: an 480 GiByte Optane in the PCIe slot, using /dev/nda0p3
> >> 
> >> with:
> >> 
> >> # gpart show -pl
> >> =>       40  468862048    da0  GPT  (224G)
> >>         40     532480  da0p1  4C8GCA72EFI  (260M)
> >>     532520       2008         - free -  (1.0M)
> >>     534528   29360128  da0p2  4C8GCA72swp14  (14G)
> >>   29894656    4194304         - free -  (2.0G)
> >>   34088960   33554432  da0p4  4C8GCA72swp16  (16G)
> >>   67643392  401217536  da0p3  4C8GCA72zfs  (191G)
> >>  468860928       1160         - free -  (580K)
> >> 
> >> =>        40  2000409184    ada0  GPT  (954G)
> >>          40      409600  ada0p1  (null)  (200M)
> >>      409640  1740636160  ada0p2  FBSDmacchroot  (830G)
> >>  1741045800    58720256  ada0p3  FBSDmacchswp0  (28G)
> >>  1799766056   176160768  ada0p4  FBSDmacchswp1  (84G)
> >>  1975926824    24482400          - free -  (12G)
> >> 
> >> =>       40  937703008    nda0  GPT  (447G)
> >>         40     532480  nda0p1  CA72opt0EFI  (260M)
> >>     532520       2008          - free -  (1.0M)
> >>     534528  117440512  nda0p2  CA72opt0swp56  (56G)
> >>  117975040   16777216          - free -  (8.0G)
> >>  134752256  134217728  nda0p4  CA72opt0swp64  (64G)
> >>  268969984  668731392  nda0p3  CA72opt0zfs  (319G)
> >>  937701376       1672          - free -  (836K)
> >> 
> >> The system running was that on /dev/ada0p2 (FBSDmacchroot,
> >> which is UFS instead of ZFS).
> >> 
> >> The [usb{usbus2}] process eventually got stuck-busy, no
> >> more I/O:
> >> 
> >> CPU 0:  0.0% user,  0.0% nice,  100% system,  0.0% interrupt,  0.0% idle
> >> CPU 1:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
> >> CPU 2:  0.0% user,  0.0% nice,  0.0% system,  0.0% interrupt,  100% idle
> >> CPU 3:  0.4% user,  0.0% nice,  0.0% system,  0.0% interrupt, 99.6% idle
> >> 
> >>  PID USERNAME    PRI NICE     SIZE       RES STATE    C   TIME     CPU COMMAND
> >>   15 root        -72    -       0B   262144B CPU0     0   8:51  99.95% [usb{usbus2}]
> >> 
> >> 1295 root         -8    0  20108Ki    8092Ki q->bq_   2   0:04   0.00% zfs recv -Fdv zpnew{receive_writer_thre}
> >> 1295 root         48    0  20108Ki    8092Ki piperd   2   0:22   0.00% zfs recv -Fdv zpnew{zfs}
> >> 1294 root         -8    0  17544Ki    7740Ki q->bq_   2   0:01   0.00% zfs send -R zpold@for-copy{send_reader_thread}
> >> 1294 root         -8    0  17544Ki    7740Ki q->bq_   0   0:00   0.00% zfs send -R zpold@for-copy{send_merge_thread}
> >> 1294 root         -8    0  17544Ki    7740Ki hdr->b   2   0:00   0.00% zfs send -R zpold@for-copy{send_traverse_threa}
> >> 1294 root         52    0  17544Ki    7740Ki range-   3   0:20   0.00% zfs send -R zpold@for-copy{zfs}
> >> 
> >> 1036 root         -8    -       0B    1488Ki t->zth   0   0:00   0.00% [zfskern{z_checkpoint_discar}]
> >> 1036 root         -8    -       0B    1488Ki t->zth   1   0:00   0.00% [zfskern{z_livelist_condense}]
> >> 1036 root         -8    -       0B    1488Ki t->zth   2   0:00   0.00% [zfskern{z_livelist_destroy}]
> >> 1036 root         -8    -       0B    1488Ki t->zth   1   0:00   0.00% [zfskern{z_indirect_condense}]
> >> 1036 root         -8    -       0B    1488Ki mmp->m   3   0:00   0.00% [zfskern{mmp_thread_enter}]
> >> 1036 root         -8    -       0B    1488Ki tx->tx   1   0:00   0.00% [zfskern{txg_thread_enter}]
> >> 1036 root         -8    -       0B    1488Ki tx->tx   2   0:00   0.00% [zfskern{txg_thread_enter}]
> >> 
> >> I was unable to ^c or ^z the process where I
> >> typed the command. I eventually stopped the
> >> system with "shutdown -p now" from a ssh
> >> session (that had already been in place).
> > 
> > Should this occur again before doing the shutdown run a
> > zpool status &
> > I have gotten in this state when the recv pool was a usb device
> 
> The USB device had the send pool in my example.
> 
> > and for some reason it had a timeout and gone offline.
> 
> No messages about timeouts or other such were made.
> 
> >  The clue
> > this occured are in dmesg, and zpool status.
> 
> No console, dmesg -a, or /var/log/messages output were
> generated. (And the system was running from a SATA SSD
> that was operating well.)
> 
> For reference, the USB EtherNet device that was in a
> USB2 port continued to operate just fine, allowing the
> use of existing ssh sessions that were displaying
> gstat -spod and top -Samio -ototal until I started
> looking at the problem. (I did not try making a new
> ssh session).
> 
> I did not do the "zpool status" so I can not report
> about it.
> 
> > Unplug/plug the USB device, check dmesg that it came online,
> > and do a zpool clear.
> 
> Okay. I normally avoid unplugging USB storage media
> if the system overall does not hang up: hopes of
> a clean shutdown leaving things better.

Do the zpool status, and only if that indicates a device offline
or other problem would you proceed to do the unplug/plug, as at
that point zfs has stopped doing anything to the device and
your shutdown wont do anything as far as zfs for that pool anyway.

> 
> The system did appear to shutdown to completion.

Yes, you can shutdown a system with a zpool in failed state.

> 
> >> 
> >> When I retried after rebooting and scrubbing (no
> >> problems found), the problem did not repeat.
> >> 
> >> I do not have more information nor a way to repeat
> >> the problem on demand, unfortunately.
> >> 
> >> Details of the vintage of the system software and
> >> such:
> >> 
> >> # ~/fbsd-based-on-what-freebsd-main.sh 
> >> FreeBSD FBSDmacch 14.0-CURRENT FreeBSD 14.0-CURRENT mm-src-n245445-def0058cc690 GENERIC-NODBG  arm64 aarch64 1400005 1400005
> >> def0058cc690 (HEAD -> mm-src) mm-src snapshot for mm's patched build in git context.
> >> merge-base: 7381bbee29df959e88ec59866cf2878263e7f3b2
> >> merge-base: CommitDate: 2021-03-12 20:29:42 +0000
> >> 7381bbee29df (freebsd/main, freebsd/HEAD, pure-src, main) cam: Run all XPT_ASYNC ccbs in a dedicated thread
> >> n245444 (--first-parent --count for merge-base)
> >> 
> >> The system was a MACCHIATObin Double Shot.
> > 
> 
> 
> 
> ===
> Mark Millard
> marklmi at yahoo.com
> ( dsl-only.net went
> away in early 2018-Mar)
> 
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-- 
Rod Grimes                                                 [email protected]
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