Strange ARC/Swap/CPU on yesterday's -CURRENT

[Justin Hibbits]

Hi Mark,

On Sat, Apr 7, 2018 at 2:49 PM, Mark Johnston <markj at freebsd.org> wrote:
> On Sat, Apr 07, 2018 at 02:34:54PM -0500, Justin Hibbits wrote:
>>
>> I reverted back to r329881, and successfully built world.  Updated to
>> r329882 and it got stuck with processes in btalloc.
>>
>> I've seen other reports of r329882 causing problems on powerpc64 as
>> well, with other bizarre behaviors.
>
> Did you try the patch that I had posted? If not, could you? Please also
> update zfs_arc_free_target or just apply D14994.

I just applied both patches, and head still locks up, but no threads
are stuck in btalloc.  The thread running when I break into ddb is
still vmdaemon.

Running 'show all vmem' on ddb shows it pretty low on kernel arena:

vmem 0xe000000001202900 'buffer arena'
        quantum:        4096
        size:   775913472
        inuse:  152928256
        free:   622985216
        busy tags:      4668
        free tags:      4
                        inuse   size            free    size
        16384           2       32768           0       0
        32768           4666    152895488       1       32768
        536870912       0       0               1       622952448
vmem 0xe000000005017000 'kernel arena dom'
        quantum:        4096
        size:   775946240
        inuse:  772923392
        free:   3022848
        busy tags:      144749
        free tags:      3
                        inuse   size            free    size
        4096            141305  578785280       0       0
        8192            243     1990656         0       0
        16384           2081    34095104        0       0
        20480           290     5939200         0       0
        32768           113     3702784         0       0
        36864           61      2248704         0       0
        65536           80      5242880         0       0
        69632           2       139264          1       69632
        77824           1       77824           0       0
        81920           1       81920           0       0
        86016           1       86016           0       0
        90112           2       180224          0       0
        94208           2       188416          0       0
        98304           1       98304           0       0
        102400          1       102400          0       0
        110592          1       110592          0       0
        118784          1       118784          0       0
        122880          1       122880          0       0
        131072          545     71434240        0       0
        262144          2       524288          9       2428928
        524288          4       2154496         1       524288
        1048576         6       6995968         0       0
        2097152         1       2097152         0       0
        4194304         1       4194304         0       0
        8388608         1       8388608         0       0
        16777216        2       43823104        0       0
vmem 0xe000000001202180 'kernel arena'
        quantum:        4096
        size:   2353004544
        inuse:  2351603712
        free:   1400832
        busy tags:      600
        free tags:      4
                        inuse   size            free    size
        4096            3       12288           1       4096
        24576           0       0               2       49152
        28672           0       0               1       28672
        36864           415     15298560        1       36864
        65536           1       65536           0       0
        131072          1       131072          0       0
        1048576         0       0               1       1282048
        4194304         172     721420288       0       0
        8388608         1       8388608         0       0
        16777216        2       46137344        0       0
        134217728       3       453386240       0       0
        268435456       1       297295872       0       0
        536870912       1       809467904       0       0

Any other numbers I can gather to debug this?

- Justin