Re: head -356426 based 32-bit powerpc (2 sock PowerMac G4): kyua sys/vm/mlock_test:mlock__copy_on_write_vnode seems stuck

[I got kernel backtrace information, included.]

On 2020-Jan-8, at 15:12, Mark Millard <marklmi at yahoo.com> wrote:

> I've attempted a head -356426 based kyua run on an
> old 2-socket PowerMac G4. The buildworld and
> buildkernel were non-debug. The context has personal
> patches, mostly for dealing with PowerMac issues.
> 
> It has had over 180 CPU minutes running for:
> 
> sys/vm/mlock_test:mlock__copy_on_write_vnode  ->  
> 
> Normal seems to be way under 0.1 sec on the
> other platforms I've made runs on recently.
> 
> Hopefully kyua will time out and continue the
> testing at some point.
> 
> The 2 socket (2 cores each) G5 powerpc64 context
> did not have this problem. Nor did the armv7 or
> aarch64 examples (CortexA7, CortexA53, CortexA57,
> and CortexA72).


I finally gave up on it after 240 CPU minutes but
could not kill/stop the stuck process. So I
sync'd the file system and tried a "shutdown -r
now" and forced the power off after it got stuck
(no reboot happened).

After power-up I tried:

# kyua test -k /usr/tests/Kyuafile sys/vm/mlock_test
sys/vm/mlock_test:mlock__copy_on_write_anon  ->  passed  [0.017s]
sys/vm/mlock_test:mlock__copy_on_write_vnode  ->  

and it got stuck again.

I'll note that ps -auxd shows the likes of:

root   1120   0.0  0.4 11512  8772  0  I+   16:38    0:00.62 | |         `-- kyua test -k /usr/tests/Kyuafile sys/vm/mlock_test
root   1124 100.0  0.1  4640  2332  -  Rs   16:38    2:57.43 | |           `-- /usr/tests/sys/vm/mlock_test -vunprivileged-user=tests -r/tmp/kyua.B2pXx8/3/result.atf mlock__copy_on_write_vnode
root   1125   0.0  0.0  4640   620  -  TXL  16:38    0:00.00 | |             `-- /usr/tests/sys/vm/mlock_test -vunprivileged-user=tests -r/tmp/kyua.B2pXx8/3/result.atf mlock__copy_on_write_vnode


I got a couple of backtraces from the kernel
via the ddb> prompt :

pid 1125 was in thread_suspend_switch called via ptracestop.

I've a couple of examples of pid 1124 (the CPU time
taker): (manually typed from screen images)

0xdc9e0520: at mi_switch+0x17c
0xdc9e0540: at critical_exit_preempt+0x7c
0xdc9e0560: at powerpc_interrupt+0x1c4
0xdc9e0590: at kernel EXI trap by __syncicache+0x5c:
            srr1= 0x209032
            r1=   0xdc9e0650
            cr=   0x8822fc22
            xer=  0
            ctr=  0
            frame=0xdc9e0598
0xdc9e0650: at 0x5ed67ec
0xdc9e0660: at moea_sync_icache+0x118
Note: From here on down is common with the
      other example backtrace:
0xdc9e0690: at pmap_sync_icache+0x98
0xdc9e06b0: at vm_sync_icache+0x2c
0xdc9e06c0: at proc_rwmem+0x13c
0xdc9e0710: at kern_ptrace+0x76c
0xdc9e0830: at sys_ptrace+0x12c
0xdc9e0960: at trap+0xae8
0xdc9e0a10: at powerpc_interrupt+0x1ec
0xdc9e0a40: at use SC trap by 0x4191ea48:
            srr1= 0x209032
            r1=   0xffffc6d0
            cr=   0x28000200
            xer=  0
            ctr=  0x4191ea40
            frame=0xdc9e0a48

The non-common part of the other backtrace
is:

0xdc9e04a0: at intr_event_handle+0xd4
0xdc9e04e0: at powerpc_dispatch_intr+0xe0
0xdc9e0520: at openpic_dispatch+0x90
0xdc9e0540: at powerpc_interrupt+0x128
0xdc9e0570: at kernel EXI trap by moea_pvo_find_va:
            srr1= 0xf032
            r1=   0xdc9e0630
            cr=   0x4822fc22
            xer=  0
            ctr=  0
            frame=0xdc9e0578
0xdc9e0630: at 0x41b76ffc
0xdc9e0660: at moea_sync_icache+0x100

Showing a lock chain showed just one line:

thread 100151 (pid 1124, mlock_test) running on CPU 0

The pcpu output for cpuid 0 metioned: critnest 2 "mlock_test"
when I tried it.

(After that I did something that locked up the machine,
probably my fault.)


It does not look like I can complete a normal kyua
run for a 2-socket 32-bit powerpc. May be someone
else can for some multi-socket 32-bit powerpc to
see if this repeats.

Single-socket/single-core might prove interesting
as well. Maybe I can try such.



===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)

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