Re: kern/56932: x68k frequently hangs up after uvm change in 9.99.75

[Tetsuya Isaki <isaki%pastel-flower.jp@localhost>]

At Thu, 21 Jul 2022 09:25:02 +0000 (UTC),
Chuck Silvers wrote:
>  the pagedaemon thread having a WAIT string of "tstile" is also
>  consistent with it being stuck waiting for a lock.
>  
>  mi_switch() being the innermost stack frame is probably correct,
>  but the trace is incomplete... there should be other functions
>  in the trace after that, with uvm_pageout() being at the end.
>  it will be very hard to figure out what's going on if ddb can't
>  report complete stack traces.

I agree.  Thank you for explanation.

>  try getting a ddb stack trace for a few other threads and see if
>  the same problem shows up with every thread.  (it probably will.)

Yes, I saw the same problem for (probably) all of kernel and user
threads.  One exception I saw is that idle/0 thread causes uvm_fault,
but I don't know details.

|db> ps
|PID   LID S CPU     FLAGS     STRUCT LWP *         NAME WAIT
|:
|0      55 3   0       200           84a440     pgdaemon tstile
|0      52 3   0       200           803940      rt_free rt_free
|:
|0   >   2 1   0       201           7dd040       idle/0
|:
|db> trace/a 84a440
|trace: pid 0 lid 55 at 0x3979dd8
|mi_switch(84a440,7c6fbc,7e,15e562,0) + 2aa
|db> trace/a 803940
|trace: pid 0 lid 52 at 0x355df14
|mi_switch(803940,7c6fbc,29ba80,7f9f28,803940) + 2aa
|db> trace/a 7dd040
|trace: pid 0 lid 2 at 0x2cddf5c
|[ 237.1956040] uvm_fault(0x2b7470, 0x1ffff000, 0x1) -> 0xe
|[ 237.1956040]   type 8, code [ mmu,,ssw]: 4010145
|[ 237.1956040] trap type 8, code = 0x4010145, v = 0x1ffffffa
|[ 237.1956040] kernel program counter = 0x4442
|[ 237.1956040] kernel: MMU fault trap
|Caught exception in ddb.
|db>

>  do you know how to figure out what's wrong with the m68k ddb
>  stack trace code, or will you need some help with that?

I don't know well about uvm and ddb area.
I'd appriciate your help.

Thanks,
---
Tetsuya Isaki <isaki%pastel-flower.jp@localhost / isaki%NetBSD.org@localhost>